Programs & Examples On #Gdb

Use this tag for problems related to or involving GDB, the standard debugger for the GNU software system.

How do I analyze a program's core dump file with GDB when it has command-line parameters?

Simple usage of GDB, to debug coredump files:

gdb <executable_path> <coredump_file_path>

A coredump file for a "process" gets created as a "core.pid" file.

After you get inside the GDB prompt (on execution of the above command), type:

...
(gdb) where

This will get you with the information, of the stack, where you can analayze the cause of the crash/fault. Other command, for the same purposes is:

...
(gdb) bt full

This is the same as above. By convention, it lists the whole stack information (which ultimately leads to the crash location).

gdb fails with "Unable to find Mach task port for process-id" error

This is a weird approach but it worked for me(MacOs HighSierra 10.13.3). Install CLion. It comes with gdb. Once run the gdb using Terminal. Copy the gdb program to your usr/local/bin/. No problem of signin, sudo etc.

How to install gdb (debugger) in Mac OSX El Capitan?

Install Homebrew first :

/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

Then run this : brew install gdb

Printing all global variables/local variables?

In case you want to see the local variables of a calling function use select-frame before info locals

E.g.:

(gdb) bt
#0  0xfec3c0b5 in _lwp_kill () from /lib/libc.so.1
#1  0xfec36f39 in thr_kill () from /lib/libc.so.1
#2  0xfebe3603 in raise () from /lib/libc.so.1
#3  0xfebc2961 in abort () from /lib/libc.so.1
#4  0xfebc2bef in _assert_c99 () from /lib/libc.so.1
#5  0x08053260 in main (argc=1, argv=0x8047958) at ber.c:480
(gdb) info locals
No symbol table info available.
(gdb) select-frame 5
(gdb) info locals
i = 28
(gdb) 

How to print register values in GDB?

Gdb commands:

  • i r <register_name>: print a single register, e.g i r rax, i r eax
  • i r <register_name_1> <register_name_2> ...: print multiple registers, e.g i r rdi rsi,
  • i r: print all register except floating point & vector register (xmm, ymm, zmm).
  • i r a: print all register, include floating point & vector register (xmm, ymm, zmm).
  • i r f: print all FPU floating registers (st0-7 and a few other f*)

Other register groups besides a (all) and f (float) can be found with:

maint print reggroups

as documented at: https://sourceware.org/gdb/current/onlinedocs/gdb/Registers.html#Registers

Tips:

  • xmm0 ~ xmm15, are 128 bits, almost every modern machine has it, they are released in 1999.
  • ymm0 ~ ymm15, are 256 bits, new machine usually have it, they are released in 2011.
  • zmm0 ~ zmm31, are 512 bits, normal pc probably don't have it (as the year 2016), they are released in 2013, and mainly used in servers so far.
  • Only one serial of xmm / ymm / zmm will be shown, because they are the same registers in different mode. On my machine ymm is shown.

Why GDB jumps unpredictably between lines and prints variables as "<value optimized out>"?

Declare found as "volatile". This should tell the compiler to NOT optimize it out.

volatile int found = 0;

How do I get the backtrace for all the threads in GDB?

Is there a command that does?

thread apply all where

How do I run a program with commandline arguments using GDB within a Bash script?

gdb -ex=r --args myprogram arg1 arg2

-ex=r is short for -ex=run and tells gdb to run your program immediately, rather than wait for you to type "run" at the prompt. Then --args says that everything that follows is the command and arguments, just as you'd normally type them at the commandline prompt.

Step out of current function with GDB

You can use the finish command.

finish: Continue running until just after function in the selected stack frame returns. Print the returned value (if any). This command can be abbreviated as fin.

(See 5.2 Continuing and Stepping.)

How to disassemble a memory range with GDB?

This isn't the direct answer to your question, but since you seem to just want to disassemble the binary, perhaps you could just use objdump:

objdump -d program

This should give you its dissassembly. You can add -S if you want it source-annotated.

Show current assembly instruction in GDB

If you want the next few instructions to display automatically while stepping through the program you can use the display command as follows -

display /3i $pc

The above will display 3 instructions whenever a breakpoint is hit or when you single step the program.

More details at the blog entry here.

gdb: "No symbol table is loaded"

You have to add extra parameter -g, which generates source level debug information. It will look like:

gcc -g prog.c

After that you can use gdb in common way.

Is there a C++ gdb GUI for Linux?

gdb -tui works okay if you want something GUI-ish, but still character based.

Counter exit code 139 when running, but gdb make it through

exit code 139 (people say this means memory fragmentation)

No, it means that your program died with signal 11 (SIGSEGV on Linux and most other UNIXes), also known as segmentation fault.

Could anybody tell me why the run fails but debug doesn't?

Your program exhibits undefined behavior, and can do anything (that includes appearing to work correctly sometimes).

Your first step should be running this program under Valgrind, and fixing all errors it reports.

If after doing the above, the program still crashes, then you should let it dump core (ulimit -c unlimited; ./a.out) and then analyze that core dump with GDB: gdb ./a.out core; then use where command.

Can I set a breakpoint on 'memory access' in GDB?

What you're looking for is called a watchpoint.

Usage

(gdb) watch foo: watch the value of variable foo

(gdb) watch *(int*)0x12345678: watch the value pointed by an address, casted to whatever type you want

(gdb) watch a*b + c/d: watch an arbitrarily complex expression, valid in the program's native language

Watchpoints are of three kinds:

  • watch: gdb will break when a write occurs
  • rwatch: gdb will break wnen a read occurs
  • awatch: gdb will break in both cases

You may choose the more appropriate for your needs.

For more information, check this out.

Can I use GDB to debug a running process?

If one want to attach a process, this process must have the same owner. The root is able to attach to any process.

How do I pass a command line argument while starting up GDB in Linux?

Another option, once inside the GDB shell, before running the program, you can do

(gdb) set args file1 file2

and inspect it with:

(gdb) show args

gdb: how to print the current line or find the current line number?

I do get the same information while debugging. Though not while I am checking the stacktrace. Most probably you would have used the optimization flag I think. Check this link - something related.

Try compiling with -g3 remove any optimization flag. Then it might work. HTH!

How do I remove a single breakpoint with GDB?

Use:

clear fileName:lineNum   // Removes all breakpoints at the specified line.
delete breakpoint number // Delete one breakpoint whose number is 'number'

no debugging symbols found when using gdb

The application has to be both compiled and linked with -g option. I.e. you need to put -g in both CPPFLAGS and LDFLAGS.

How to modify memory contents using GDB?

Expanding on the answers provided here.

You can just do set idx = 1 to set a variable, but that syntax is not recommended because the variable name may clash with a set sub-command. As an example set w=1 would not be valid.

This means that you should prefer the syntax: set variable idx = 1 or set var idx = 1.

Last but not least, you can just use your trusty old print command, since it evaluates an expression. The only difference being that he also prints the result of the expression.

(gdb) p idx = 1
$1 = 1

You can read more about gdb here.

Using gdb to single-step assembly code outside specified executable causes error "cannot find bounds of current function"

You can use stepi or nexti (which can be abbreviated to si or ni) to step through your machine code.

Core dump file analysis

You just need a binary (with debugging symbols included) that is identical to the one that generated the core dump file. Then you can run gdb path/to/the/binary path/to/the/core/dump/file to debug it.

When it starts up, you can use bt (for backtrace) to get a stack trace from the time of the crash. In the backtrace, each function invocation is given a number. You can use frame number (replacing number with the corresponding number in the stack trace) to select a particular stack frame.

You can then use list to see code around that function, and info locals to see the local variables. You can also use print name_of_variable (replacing "name_of_variable" with a variable name) to see its value.

Typing help within GDB will give you a prompt that will let you see additional commands.

How do I print the elements of a C++ vector in GDB?

put the following in ~/.gdbinit

define print_vector
    if $argc == 2
        set $elem = $arg0.size()
        if $arg1 >= $arg0.size()
            printf "Error, %s.size() = %d, printing last element:\n", "$arg0", $arg0.size()
            set $elem = $arg1 -1
        end
        print *($arg0._M_impl._M_start + $elem)@1
    else
        print *($arg0._M_impl._M_start)@$arg0.size()
    end
end

document print_vector
Display vector contents
Usage: print_vector VECTOR_NAME INDEX
VECTOR_NAME is the name of the vector
INDEX is an optional argument specifying the element to display
end

After restarting gdb (or sourcing ~/.gdbinit), show the associated help like this

gdb) help print_vector
Display vector contents
Usage: print_vector VECTOR_NAME INDEX
VECTOR_NAME is the name of the vector
INDEX is an optional argument specifying the element to display

Example usage:

(gdb) print_vector videoconfig_.entries 0
$32 = {{subChannelId = 177 '\261', sourceId = 0 '\000', hasH264PayloadInfo = false, bitrate = 0,     payloadType = 68 'D', maxFs = 0, maxMbps = 0, maxFps = 134, encoder = 0 '\000', temporalLayers = 0 '\000'}}

How to pass arguments and redirect stdin from a file to program run in gdb?

Wouldn't it be nice to just type debug in front of any command to be able to debug it with gdb on shell level?

Below it this function. It even works with following:

"$program" "$@" < <(in) 1> >(out) 2> >(two) 3> >(three)

This is a call where you cannot control anything, everything is variable, can contain spaces, linefeeds and shell metacharacters. In this example, in, out, two, and three are arbitrary other commands which consume or produce data which must not be harmed.

Following bash function invokes gdb nearly cleanly in such an environment [Gist]:

debug()
{
  1000<&0 1001>&1 1002>&2 \
  0</dev/tty 1>/dev/tty 2>&0 \
  /usr/bin/gdb -q -nx -nw \
  -ex 'set exec-wrapper /bin/bash -c "exec 0<&1000 1>&1001 2>&1002 \"\$@\"" exec' \
  -ex r \
  --args "$@";
}

Example on how to apply this: Just type debug in front:

Before:

p=($'\n' $'I\'am\'evil' "  yay  ")
"b u g" "${p[@]}" < <(in) 1> >(out) 2> >(two) 3> >(three)

After:

p=($'\n' $'I\'am\'evil' "  yay  ")
debug "b u g" "${p[@]}" < <(in) 1> >(out) 2> >(two) 3> >(three)

That's it. Now it's an absolute no-brainer to debug with gdb. Except for a few details or more:

  • gdb does not quit automatically and hence keeps the IO redirection open until you exit gdb. But I call this a feature.

  • You cannot easily pass argv0 to the program like with exec -a arg0 command args. Following should do this trick: After exec-wrapper change "exec to "exec -a \"\${DEBUG_ARG0:-\$1}\".

  • There are FDs above 1000 open, which are normally closed. If this is a problem, change 0<&1000 1>&1001 2>&1002 to read 0<&1000 1>&1001 2>&1002 1000<&- 1001>&- 1002>&-

  • You cannot run two debuggers in parallel. There also might be issues, if some other command consumes /dev/tty (or STDIN). To fix that, replace /dev/tty with "${DEBUGTTY:-/dev/tty}". In some other TTY type tty; sleep inf and then use the printed TTY (i. E. /dev/pts/60) for debugging, as in DEBUGTTY=/dev/pts/60 debug command arg... That's the Power of Shell, get used to it!

Function explained:

  • 1000<&0 1001>&1 1002>&2 moves away the first 3 FDs
    • This assumes, that FDs 1000, 1001 and 1002 are free
  • 0</dev/tty 1>/dev/tty 2>&0 restores the first 3 FDs to point to your current TTY. So you can control gdb.
  • /usr/bin/gdb -q -nx -nw runs gdb invokes gdb on shell
  • -ex 'set exec-wrapper /bin/bash -c "exec 0<&1000 1>&1001 2>&1002 \"\$@\"" creates a startup wrapper, which restores the first 3 FDs which were saved to 1000 and above
  • -ex r starts the program using the exec-wrapper
  • --args "$@" passes the arguments as given

Wasn't that easy?

How can one see content of stack with GDB?

Use:

  • bt - backtrace: show stack functions and args
  • info frame - show stack start/end/args/locals pointers
  • x/100x $sp - show stack memory
(gdb) bt
#0  zzz () at zzz.c:96
#1  0xf7d39cba in yyy (arg=arg@entry=0x0) at yyy.c:542
#2  0xf7d3a4f6 in yyyinit () at yyy.c:590
#3  0x0804ac0c in gnninit () at gnn.c:374
#4  main (argc=1, argv=0xffffd5e4) at gnn.c:389

(gdb) info frame
Stack level 0, frame at 0xffeac770:
 eip = 0x8049047 in main (goo.c:291); saved eip 0xf7f1fea1
 source language c.
 Arglist at 0xffeac768, args: argc=1, argv=0xffffd5e4
 Locals at 0xffeac768, Previous frame's sp is 0xffeac770
 Saved registers:
  ebx at 0xffeac75c, ebp at 0xffeac768, esi at 0xffeac760, edi at 0xffeac764, eip at 0xffeac76c

(gdb) x/10x $sp
0xffeac63c: 0xf7d39cba  0xf7d3c0d8  0xf7d3c21b  0x00000001
0xffeac64c: 0xf78d133f  0xffeac6f4  0xf7a14450  0xffeac678
0xffeac65c: 0x00000000  0xf7d3790e

What does <value optimized out> mean in gdb?

Minimal runnable example with disassembly analysis

As usual, I like to see some disassembly to get a better understanding of what is going on.

In this case, the insight we obtain is that if a variable is optimized to be stored only in a register rather than the stack, and then the register it was in gets overwritten, then it shows as <optimized out> as mentioned by R..

Of course, this can only happen if the variable in question is not needed anymore, otherwise the program would lose its value. Therefore it tends to happen that at the start of the function you can see the variable value, but then at the end it becomes <optimized out>.

One typical case which we often are interested in of this is that of the function arguments themselves, since these are:

  • always defined at the start of the function
  • may not get used towards the end of the function as more intermediate values are calculated.
  • tend to get overwritten by further function subcalls which must setup the exact same registers to satisfy the calling convention

This understanding actually has a concrete application: when using reverse debugging, you might be able to recover the value of variables of interest simply by stepping back to their last point of usage: How do I view the value of an <optimized out> variable in C++?

main.c

#include <stdio.h>

int __attribute__((noinline)) f3(int i) {
    return i + 1;
}

int __attribute__((noinline)) f2(int i) {
    return f3(i) + 1;
}

int __attribute__((noinline)) f1(int i) {
    int j = 1, k = 2, l = 3;
    i += 1;
    j += f2(i);
    k += f2(j);
    l += f2(k);
    return l;
}

int main(int argc, char *argv[]) {
    printf("%d\n", f1(argc));
    return 0;
}

Compile and run:

gcc -ggdb3 -O3 -std=c99 -Wall -Wextra -pedantic -o main.out main.c
gdb -q -nh main.out

Then inside GDB, we have the following session:

Breakpoint 1, f1 (i=1) at main.c:13
13          i += 1;
(gdb) disas
Dump of assembler code for function f1:
=> 0x00005555555546c0 <+0>:     add    $0x1,%edi
   0x00005555555546c3 <+3>:     callq  0x5555555546b0 <f2>
   0x00005555555546c8 <+8>:     lea    0x1(%rax),%edi
   0x00005555555546cb <+11>:    callq  0x5555555546b0 <f2>
   0x00005555555546d0 <+16>:    lea    0x2(%rax),%edi
   0x00005555555546d3 <+19>:    callq  0x5555555546b0 <f2>
   0x00005555555546d8 <+24>:    add    $0x3,%eax
   0x00005555555546db <+27>:    retq   
End of assembler dump.
(gdb) p i
$1 = 1
(gdb) p j
$2 = 1
(gdb) n
14          j += f2(i);
(gdb) disas
Dump of assembler code for function f1:
   0x00005555555546c0 <+0>:     add    $0x1,%edi
=> 0x00005555555546c3 <+3>:     callq  0x5555555546b0 <f2>
   0x00005555555546c8 <+8>:     lea    0x1(%rax),%edi
   0x00005555555546cb <+11>:    callq  0x5555555546b0 <f2>
   0x00005555555546d0 <+16>:    lea    0x2(%rax),%edi
   0x00005555555546d3 <+19>:    callq  0x5555555546b0 <f2>
   0x00005555555546d8 <+24>:    add    $0x3,%eax
   0x00005555555546db <+27>:    retq   
End of assembler dump.
(gdb) p i
$3 = 2
(gdb) p j
$4 = 1
(gdb) n
15          k += f2(j);
(gdb) disas
Dump of assembler code for function f1:
   0x00005555555546c0 <+0>:     add    $0x1,%edi
   0x00005555555546c3 <+3>:     callq  0x5555555546b0 <f2>
   0x00005555555546c8 <+8>:     lea    0x1(%rax),%edi
=> 0x00005555555546cb <+11>:    callq  0x5555555546b0 <f2>
   0x00005555555546d0 <+16>:    lea    0x2(%rax),%edi
   0x00005555555546d3 <+19>:    callq  0x5555555546b0 <f2>
   0x00005555555546d8 <+24>:    add    $0x3,%eax
   0x00005555555546db <+27>:    retq   
End of assembler dump.
(gdb) p i
$5 = <optimized out>
(gdb) p j
$6 = 5
(gdb) n
16          l += f2(k);
(gdb) disas
Dump of assembler code for function f1:
   0x00005555555546c0 <+0>:     add    $0x1,%edi
   0x00005555555546c3 <+3>:     callq  0x5555555546b0 <f2>
   0x00005555555546c8 <+8>:     lea    0x1(%rax),%edi
   0x00005555555546cb <+11>:    callq  0x5555555546b0 <f2>
   0x00005555555546d0 <+16>:    lea    0x2(%rax),%edi
=> 0x00005555555546d3 <+19>:    callq  0x5555555546b0 <f2>
   0x00005555555546d8 <+24>:    add    $0x3,%eax
   0x00005555555546db <+27>:    retq   
End of assembler dump.
(gdb) p i
$7 = <optimized out>
(gdb) p j
$8 = <optimized out>

To understand what is going on, remember from the x86 Linux calling convention: What are the calling conventions for UNIX & Linux system calls on i386 and x86-64 you should know that:

  • RDI contains the first argument
  • RDI can get destroyed in function calls
  • RAX contains the return value

From this we deduce that:

add    $0x1,%edi

corresponds to the:

i += 1;

since i is the first argument of f1, and therefore stored in RDI.

Now, while we were at both:

i += 1;
j += f2(i);

the value of RDI hadn't been modified, and therefore GDB could just query it at anytime in those lines.

However, as soon as the f2 call is made:

  • the value of i is not needed anymore in the program
  • lea 0x1(%rax),%edi does EDI = j + RAX + 1, which both:
    • initializes j = 1
    • sets up the first argument of the next f2 call to RDI = j

Therefore, when the following line is reached:

k += f2(j);

both of the following instructions have/may have modified RDI, which is the only place i was being stored (f2 may use it as a scratch register, and lea definitely set it to RAX + 1):

   0x00005555555546c3 <+3>:     callq  0x5555555546b0 <f2>
   0x00005555555546c8 <+8>:     lea    0x1(%rax),%edi

and so RDI does not contain the value of i anymore. In fact, the value of i was completely lost! Therefore the only possible outcome is:

$3 = <optimized out>

A similar thing happens to the value of j, although j only becomes unnecessary one line later afer the call to k += f2(j);.

Thinking about j also gives us some insight on how smart GDB is. Notably, at i += 1;, the value of j had not yet materialized in any register or memory address, and GDB must have known it based solely on debug information metadata.

-O0 analysis

If we use -O0 instead of -O3 for compilation:

gcc -ggdb3 -O0 -std=c99 -Wall -Wextra -pedantic -o main.out main.c

then the disassembly would look like:

11      int __attribute__((noinline)) f1(int i) {
=> 0x0000555555554673 <+0>:     55      push   %rbp
   0x0000555555554674 <+1>:     48 89 e5        mov    %rsp,%rbp
   0x0000555555554677 <+4>:     48 83 ec 18     sub    $0x18,%rsp
   0x000055555555467b <+8>:     89 7d ec        mov    %edi,-0x14(%rbp)

12          int j = 1, k = 2, l = 3;
   0x000055555555467e <+11>:    c7 45 f4 01 00 00 00    movl   $0x1,-0xc(%rbp)
   0x0000555555554685 <+18>:    c7 45 f8 02 00 00 00    movl   $0x2,-0x8(%rbp)
   0x000055555555468c <+25>:    c7 45 fc 03 00 00 00    movl   $0x3,-0x4(%rbp)

13          i += 1;
   0x0000555555554693 <+32>:    83 45 ec 01     addl   $0x1,-0x14(%rbp)

14          j += f2(i);
   0x0000555555554697 <+36>:    8b 45 ec        mov    -0x14(%rbp),%eax
   0x000055555555469a <+39>:    89 c7   mov    %eax,%edi
   0x000055555555469c <+41>:    e8 b8 ff ff ff  callq  0x555555554659 <f2>
   0x00005555555546a1 <+46>:    01 45 f4        add    %eax,-0xc(%rbp)

15          k += f2(j);
   0x00005555555546a4 <+49>:    8b 45 f4        mov    -0xc(%rbp),%eax
   0x00005555555546a7 <+52>:    89 c7   mov    %eax,%edi
   0x00005555555546a9 <+54>:    e8 ab ff ff ff  callq  0x555555554659 <f2>
   0x00005555555546ae <+59>:    01 45 f8        add    %eax,-0x8(%rbp)

16          l += f2(k);
   0x00005555555546b1 <+62>:    8b 45 f8        mov    -0x8(%rbp),%eax
   0x00005555555546b4 <+65>:    89 c7   mov    %eax,%edi
   0x00005555555546b6 <+67>:    e8 9e ff ff ff  callq  0x555555554659 <f2>
   0x00005555555546bb <+72>:    01 45 fc        add    %eax,-0x4(%rbp)

17          return l;
   0x00005555555546be <+75>:    8b 45 fc        mov    -0x4(%rbp),%eax

18      }
   0x00005555555546c1 <+78>:    c9      leaveq 
   0x00005555555546c2 <+79>:    c3      retq 

From this horrendous disassembly, we see that the value of RDI is moved to the stack at the very start of program execution at:

mov    %edi,-0x14(%rbp)

and it then gets retrieved from memory into registers whenever needed, e.g. at:

14          j += f2(i);
   0x0000555555554697 <+36>:    8b 45 ec        mov    -0x14(%rbp),%eax
   0x000055555555469a <+39>:    89 c7   mov    %eax,%edi
   0x000055555555469c <+41>:    e8 b8 ff ff ff  callq  0x555555554659 <f2>
   0x00005555555546a1 <+46>:    01 45 f4        add    %eax,-0xc(%rbp)

The same basically happens to j which gets immediately pushed to the stack when when it is initialized:

   0x000055555555467e <+11>:    c7 45 f4 01 00 00 00    movl   $0x1,-0xc(%rbp)

Therefore, it is easy for GDB to find the values of those variables at any time: they are always present in memory!

This also gives us some insight on why it is not possible to avoid <optimized out> in optimized code: since the number of registers is limited, the only way to do that would be to actually push unneeded registers to memory, which would partly defeat the benefit of -O3.

Extend the lifetime of i

If we edited f1 to return l + i as in:

int __attribute__((noinline)) f1(int i) {
    int j = 1, k = 2, l = 3;
    i += 1;
    j += f2(i);
    k += f2(j);
    l += f2(k);
    return l + i;
}

then we observe that this effectively extends the visibility of i until the end of the function.

This is because with this we force GCC to use an extra variable to keep i around until the end:

   0x00005555555546c0 <+0>:     lea    0x1(%rdi),%edx
   0x00005555555546c3 <+3>:     mov    %edx,%edi
   0x00005555555546c5 <+5>:     callq  0x5555555546b0 <f2>
   0x00005555555546ca <+10>:    lea    0x1(%rax),%edi
   0x00005555555546cd <+13>:    callq  0x5555555546b0 <f2>
   0x00005555555546d2 <+18>:    lea    0x2(%rax),%edi
   0x00005555555546d5 <+21>:    callq  0x5555555546b0 <f2>
   0x00005555555546da <+26>:    lea    0x3(%rdx,%rax,1),%eax
   0x00005555555546de <+30>:    retq

which the compiler does by storing i += i in RDX at the very first instruction.

Tested in Ubuntu 18.04, GCC 7.4.0, GDB 8.1.0.

GDB: break if variable equal value

There are hardware and software watchpoints. They are for reading and for writing a variable. You need to consult a tutorial:

http://www.unknownroad.com/rtfm/gdbtut/gdbwatch.html

To set a watchpoint, first you need to break the code into a place where the varianle i is present in the environment, and set the watchpoint.

watch command is used to set a watchpoit for writing, while rwatch for reading, and awatch for reading/writing.

Core dump file is not generated

Just in case someone else stumbles on this. I was running someone else's code - make sure they are not handling the signal, so they can gracefully exit. I commented out the handling, and got the core dump.

How do I set a conditional breakpoint in gdb, when char* x points to a string whose value equals "hello"?

break x if ((int)strcmp(y, "hello")) == 0

On some implementations gdb might not know the return type of strcmp. That means you would have to cast, otherwise it would always evaluate to true!

GDB: Listing all mapped memory regions for a crashed process

If you have the program and the core file, you can do the following steps.

1) Run the gdb on the program along with core file

 $gdb ./test core

2) type info files and see what different segments are there in the core file.

    (gdb)info files

A sample output:

    (gdb)info files 

    Symbols from "/home/emntech/debugging/test".
    Local core dump file:
`/home/emntech/debugging/core', file type elf32-i386.
  0x0055f000 - 0x0055f000 is load1
  0x0057b000 - 0x0057c000 is load2
  0x0057c000 - 0x0057d000 is load3
  0x00746000 - 0x00747000 is load4
  0x00c86000 - 0x00c86000 is load5
  0x00de0000 - 0x00de0000 is load6
  0x00de1000 - 0x00de3000 is load7
  0x00de3000 - 0x00de4000 is load8
  0x00de4000 - 0x00de7000 is load9
  0x08048000 - 0x08048000 is load10
  0x08049000 - 0x0804a000 is load11
  0x0804a000 - 0x0804b000 is load12
  0xb77b9000 - 0xb77ba000 is load13
  0xb77cc000 - 0xb77ce000 is load14
  0xbf91d000 - 0xbf93f000 is load15

In my case I have 15 segments. Each segment has start of the address and end of the address. Choose any segment to search data for. For example lets select load11 and search for a pattern. Load11 has start address 0x08049000 and ends at 0x804a000.

3) Search for a pattern in the segment.

(gdb) find /w 0x08049000 0x0804a000 0x8048034
 0x804903c
 0x8049040
 2 patterns found

If you don't have executable file you need to use a program which prints data of all segments of a core file. Then you can search for a particular data at an address. I don't find any program as such, you can use the program at the following link which prints data of all segments of a core or an executable file.

 http://emntech.com/programs/printseg.c

How to attach a process in gdb

Try one of these:

gdb -p 12271
gdb /path/to/exe 12271

gdb /path/to/exe
(gdb) attach 12271

How do I print the full value of a long string in gdb?

As long as your program's in a sane state, you can also call (void)puts(your_string) to print it to stdout. Same principle applies to all functions available to the debugger, actually.

Python : List of dict, if exists increment a dict value, if not append a new dict

This always works fine for me:

for url in list_of_urls:
    urls.setdefault(url, 0)
    urls[url] += 1

How to make a website secured with https

What kind of business data? Trade secrets or just stuff that they don't want people to see but if it got out, it wouldn't be a big deal? If we are talking trade secrets, financial information, customer information and stuff that's generally confidential. Then don't even go down that route.

I'm wondering whether I need to use a secured connection (https) or just the forms authentication is enough.

Use a secure connection all the way.

Do I need to alter the code / Config

Yes. Well may be not. You may want to have an expert do this for you.

Is SSL and https one and the same...

Mostly yes. People usually refer to those things as the same thing.

Do I need to apply with someone to get some license or something.

You probably want to have your certificate signed by a certificate authority. It will cost you or your client a bit of money.

Do I need to make all my pages secured or only the login page...

Use https throughout. Performance is usually not an issue if the site is meant for internal users.

I was searching Internet for answer, but I was not able to get all these points... Any whitepaper or other references would also be helpful...

Start here for some pointers: http://www.owasp.org/index.php/Category:OWASP_Guide_Project

Note that SSL is a minuscule piece of making your web site secure once it is accessible from the internet. It does not prevent most sort of hacking.

How to convert a std::string to const char* or char*?

char* result = strcpy((char*)malloc(str.length()+1), str.c_str());

How do I display an alert dialog on Android?

Try this code

AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(MainActivity.this);

    // set title
    alertDialogBuilder.setTitle("AlertDialog Title");

    // set dialog message
    alertDialogBuilder
            .setMessage("Some Alert Dialog message.")
            .setCancelable(false)
            .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                            Toast.makeText(this, "OK button click ", Toast.LENGTH_SHORT).show();

                }
            })
            .setNegativeButton("CANCEL",new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                           Toast.makeText(this, "CANCEL button click ", Toast.LENGTH_SHORT).show();

                    dialog.cancel();
                }
            });

    // create alert dialog
    AlertDialog alertDialog = alertDialogBuilder.create();

    // show it
    alertDialog.show();

Why call git branch --unset-upstream to fixup?

Issue: Your branch is based on 'origin/master', but the upstream is gone.

Solution: git branch --unset-upstream

How to view the roles and permissions granted to any database user in Azure SQL server instance?

if you want to find about object name e.g. table name and stored procedure on which particular user has permission, use the following query:

SELECT pr.principal_id, pr.name, pr.type_desc, 
    pr.authentication_type_desc, pe.state_desc, pe.permission_name, OBJECT_NAME(major_id) objectName
FROM sys.database_principals AS pr
JOIN sys.database_permissions AS pe ON pe.grantee_principal_id = pr.principal_id
--INNER JOIN sys.schemas AS s ON s.principal_id =  sys.database_role_members.role_principal_id 
     where pr.name in ('youruser1','youruser2') 

How to return a html page from a restful controller in spring boot?

@Controller
public class WebController {
@GetMapping("/")

public String homePage() {
    return "index";
  }
}

Python JSON serialize a Decimal object

If you want to pass a dictionary containing decimals to the requests library (using the json keyword argument), you simply need to install simplejson:

$ pip3 install simplejson    
$ python3
>>> import requests
>>> from decimal import Decimal
>>> # This won't error out:
>>> requests.post('https://www.google.com', json={'foo': Decimal('1.23')})

The reason of the problem is that requests uses simplejson only if it is present, and falls back to the built-in json if it is not installed.

Google Script to see if text contains a value

Google Apps Script is javascript, you can use all the string methods...

var grade = itemResponse.getResponse();
if(grade.indexOf("9th")>-1){do something }

You can find doc on many sites, this one for example.

gnuplot - adjust size of key/legend

To adjust the length of the samples:

set key samplen X

(default is 4)

To adjust the vertical spacing of the samples:

set key spacing X

(default is 1.25)

and (for completeness), to adjust the fontsize:

set key font "<face>,<size>"

(default depends on the terminal)

And of course, all these can be combined into one line:

set key samplen 2 spacing .5 font ",8"

Note that you can also change the position of the key using set key at <position> or any one of the pre-defined positions (which I'll just defer to help key at this point)

MySQL Alter Table Add Field Before or After a field already present

$query = "ALTER TABLE `" . $table_prefix . "posts_to_bookmark` 
          ADD COLUMN `ping_status` INT(1) NOT NULL 
          AFTER `<TABLE COLUMN BEFORE THIS COLUMN>`";

I believe you need to have ADD COLUMN and use AFTER, not BEFORE.

In case you want to place column at the beginning of a table, use the FIRST statement:

$query = "ALTER TABLE `" . $table_prefix . "posts_to_bookmark`
          ADD COLUMN `ping_status` INT(1) NOT NULL 
          FIRST";

http://dev.mysql.com/doc/refman/5.1/en/alter-table.html

How to set an image as a background for Frame in Swing GUI of java?

Perhaps the easiest way would be to add an image, scale it, and set it to the JFrame/JPanel (in my case JPanel) but remember to "add" it to the container only after you've added the other children components. enter image description here

    ImageIcon background=new ImageIcon("D:\\FeedbackSystem\\src\\images\\background.jpg");
    Image img=background.getImage();
    Image temp=img.getScaledInstance(500,600,Image.SCALE_SMOOTH);
    background=new ImageIcon(temp);
    JLabel back=new JLabel(background);
    back.setLayout(null);
    back.setBounds(0,0,500,600);

Printing Lists as Tabular Data

The following function will create the requested table (with or without numpy) with Python 3 (maybe also Python 2). I have chosen to set the width of each column to match that of the longest team name. You could modify it if you wanted to use the length of the team name for each column, but will be more complicated.

Note: For a direct equivalent in Python 2 you could replace the zip with izip from itertools.

def print_results_table(data, teams_list):
    str_l = max(len(t) for t in teams_list)
    print(" ".join(['{:>{length}s}'.format(t, length = str_l) for t in [" "] + teams_list]))
    for t, row in zip(teams_list, data):
        print(" ".join(['{:>{length}s}'.format(str(x), length = str_l) for x in [t] + row]))

teams_list = ["Man Utd", "Man City", "T Hotspur"]
data = [[1, 2, 1],
        [0, 1, 0],
        [2, 4, 2]]

print_results_table(data, teams_list)

This will produce the following table:

            Man Utd  Man City T Hotspur
  Man Utd         1         2         1
 Man City         0         1         0
T Hotspur         2         4         2

If you want to have vertical line separators, you can replace " ".join with " | ".join.

References:

Force Intellij IDEA to reread all maven dependencies

For IntelliJ IDEA 14.0

Project > [your project name] > right click > Maven > Reimport

Gradle proxy configuration

There are 2 ways for using Gradle behind a proxy :

Add arguments in command line

(From Guillaume Berche's post)

Add these arguments in your gradle command :

-Dhttp.proxyHost=your_proxy_http_host -Dhttp.proxyPort=your_proxy_http_port

or these arguments if you are using https :

-Dhttps.proxyHost=your_proxy_https_host -Dhttps.proxyPort=your_proxy_https_port

Add lines in gradle configuration file

in gradle.properties add the following lines :

systemProp.http.proxyHost=your_proxy_http_host
systemProp.http.proxyPort=your_proxy_http_port
systemProp.https.proxyHost=your_proxy_https_host
systemProp.https.proxyPort=your_proxy_https_port

(for gradle.properties file location, please refer to official documentation https://docs.gradle.org/current/userguide/build_environment.html


EDIT : as said by @Joost : A small but important detail that I initially overlooked: notice that the actual host name does NOT contain http:// protocol part of the URL...

get dataframe row count based on conditions

You are asking for the condition where all the conditions are true, so len of the frame is the answer, unless I misunderstand what you are asking

In [17]: df = DataFrame(randn(20,4),columns=list('ABCD'))

In [18]: df[(df['A']>0) & (df['B']>0) & (df['C']>0)]
Out[18]: 
           A         B         C         D
12  0.491683  0.137766  0.859753 -1.041487
13  0.376200  0.575667  1.534179  1.247358
14  0.428739  1.539973  1.057848 -1.254489

In [19]: df[(df['A']>0) & (df['B']>0) & (df['C']>0)].count()
Out[19]: 
A    3
B    3
C    3
D    3
dtype: int64

In [20]: len(df[(df['A']>0) & (df['B']>0) & (df['C']>0)])
Out[20]: 3

Inline functions in C#?

The statement "its best to leave these things alone and let the compiler do the work.." (Cody Brocious) is complete rubish. I have been programming high performance game code for 20 years, and I have yet to come across a compiler that is 'smart enough' to know which code should be inlined (functions) or not. It would be useful to have a "inline" statement in c#, truth is that the compiler just doesnt have all the information it needs to determine which function should be always inlined or not without the "inline" hint. Sure if the function is small (accessor) then it might be automatically inlined, but what if it is a few lines of code? Nonesense, the compiler has no way of knowing, you cant just leave that up to the compiler for optimized code (beyond algorithims).

SEVERE: Unable to create initial connections of pool - tomcat 7 with context.xml file

When you encounter exceptions like this, the most useful information is generally at the bottom of the stacktrace:

Caused by: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
  at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
  ...
  at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:246)

The problem is that Tomcat can't find com.mysql.jdbc.Driver. This is usually caused by the JAR containing the MySQL driver not being where Tomcat expects to find it (namely in the webapps/<yourwebapp>/WEB-INF/lib directory).

How to create large PDF files (10MB, 50MB, 100MB, 200MB, 500MB, 1GB, etc.) for testing purposes?

Partly it depends on what you are trying to increase the size of... number of pages, number of images, size of a single image. In my experience, the vast bulk (90%+) of any given 'large' PDF file will be the images.

You could try using a pro product like Adobe InDesign to quickly build a large project and export it as a PDF.

Adobe Acrobat Pro has built-in tools to optimize PDF files -- you try using the tools to 'un-optimize' your file. :)

AngularJS access scope from outside js function

You can also try:

function change() {
    var scope = angular.element( document.getElementById('outer') ).scope();
    scope.$apply(function(){
        scope.msg = 'Superhero';
    })
}

How to get the current time in Google spreadsheet using script editor?

I considered with timezone in my Google Docs like this:

timezone = "GMT+" + new Date().getTimezoneOffset()/60
var date = Utilities.formatDate(new Date(), timezone, "yyyy-MM-dd HH:mm"); // "yyyy-MM-dd'T'HH:mm:ss'Z'"

my script for Google docs

How to create a hex dump of file containing only the hex characters without spaces in bash?

xxd -p file

Or if you want it all on a single line:

xxd -p file | tr -d '\n'

How to define static constant in a class in swift

Some might want certain class constants public while others private.

private keyword can be used to limit the scope of constants within the same swift file.

class MyClass {

struct Constants {

    static let testStr = "test"
    static let testStrLen = testStr.characters.count

    //testInt will not be accessable by other classes in different swift files
    private static let testInt = 1
}

func ownFunction()
{

    var newInt = Constants.testInt + 1

    print("Print testStr=\(Constants.testStr)")
}

}

Other classes will be able to access your class constants like below

class MyClass2
{

func accessOtherConstants()
{
    print("MyClass's testStr=\(MyClass.Constants.testStr)")
}

} 

converting multiple columns from character to numeric format in r

I think I figured it out. Here's what I did (perhaps not the most elegant solution - suggestions on how to imp[rove this are very much welcome)

#names of columns in data frame
cols <- names(DF)
# character variables
cols.char <- c("fx_code","date")
#numeric variables
cols.num <- cols[!cols %in% cols.char]

DF.char <- DF[cols.char]
DF.num <- as.data.frame(lapply(DF[cols.num],as.numeric))
DF2 <- cbind(DF.char, DF.num)

ssl.SSLError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749)

I ran this on MacOS /Applications/Python\ 3.6/Install\ Certificates.command

How to display Base64 images in HTML?

The + character occurring in a data URI should be encoded as %2B. This is like encoding any other string in a URI. For example, argument separators (? and &) must be encoded when a URI with an argument is sent as part of another URI.

How to properly compare two Integers in Java?

Because comparaison method have to be done based on type int (x==y) or class Integer (x.equals(y)) with right operator

public class Example {

    public static void main(String[] args) {
     int[] arr = {-32735, -32735, -32700, -32645, -32645, -32560, -32560};

        for(int j=1; j<arr.length-1; j++)
            if((arr[j-1]!=arr[j]) && (arr[j]!=arr[j+1])) 
                System.out.println("int>"+arr[j]);


    Integer[] I_arr = {-32735, -32735, -32700, -32645, -32645, -32560, -32560};

        for(int j=1; j<I_arr.length-1; j++)
            if((!I_arr[j-1].equals(I_arr[j])) && (!I_arr[j].equals(I_arr[j+1]))) 
                System.out.println("Interger>"+I_arr[j]);
    }
}

Conversion of System.Array to List

Interestingly no one answers the question, OP isn't using a strongly typed int[] but an Array.

You have to cast the Array to what it actually is, an int[], then you can use ToList:

List<int> intList = ((int[])ints).ToList();

Note that Enumerable.ToList calls the list constructor that first checks if the argument can be casted to ICollection<T>(which an array implements), then it will use the more efficient ICollection<T>.CopyTo method instead of enumerating the sequence.

Get paragraph text inside an element

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Where to JavaScript</title>
    <!-- JavaScript in head tag-->
    <script>
        function changeHtmlContent() {
            var content = document.getElementById('content').textContent;
            alert(content);
        }
    </script>
</head>
<body>
    <h4 id="content">Welcome to JavaScript!</h4>
    <button onclick="changeHtmlContent()">Change the content</button>
</body>

Here, we can get the text content of h4 by using:

document.getElementById('content').textContent

how to set width for PdfPCell in ItextSharp

try this code I think it is more optimal.

HeaderRow is used to repeat the header of the table for each new page automatically

        BaseFont bfTimes = BaseFont.CreateFont(BaseFont.TIMES_ROMAN, BaseFont.CP1252, false);
        iTextSharp.text.Font times = new iTextSharp.text.Font(bfTimes, 6, iTextSharp.text.Font.NORMAL, iTextSharp.text.BaseColor.BLACK);

        PdfPTable table = new PdfPTable(10) { HorizontalAlignment = Element.ALIGN_CENTER, WidthPercentage = 100, HeaderRows = 2 };
        table.SetWidths(new float[] { 2f, 6f, 6f, 3f, 5f, 8f, 5f, 5f, 5f, 5f });
        table.AddCell(new PdfPCell(new Phrase("SER.\nNO.", times)) { Rowspan = 2, GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("TYPE OF SHIPPING", times)) { GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("ORDER NO.", times)) { GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("QTY.", times)) { GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("DISCHARGE PPORT", times)) { GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("DESCRIPTION OF GOODS", times)) { Rowspan = 2, GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("LINE DOC. RECL DATE", times)) { GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("CLEARANCE DATE", times)) { Rowspan = 2, GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("CUSTOM PERMIT NO.", times)) { Rowspan = 2, GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("DISPATCH DATE", times)) { Rowspan = 2, GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("AWB/BL NO.", times)) { GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("COMPLEX NAME", times)) { GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("G. W. Kgs.", times)) { GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("DESTINATION", times)) { GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("OWNER DOC. RECL DATE", times)) { GrayFill = 0.95f });

Get GPS location from the web browser

To give a bit more specific answer. HTML5 allows you to get the geo coordinates, and it does a pretty decent job. Overall the browser support for geolocation is pretty good, all major browsers except ie7 and ie8 (and opera mini). IE9 does the job but is the worst performer. Checkout caniuse.com:

http://caniuse.com/#search=geol

Also you need the approval of your user to access their location, so make sure you check for this and give some decent instructions in case it's turned off. Especially for Iphone turning permissions on for Safari is a bit cumbersome.

Change remote repository credentials (authentication) on Intellij IDEA 14

After trying several answers, I was finally able to solve this issue (on window 10),

>git fetch
remote: HTTP Basic: Access denied
fatal: Authentication failed for 'http://gitlab.abc.net/V4/VH.git/'

By updating the password stored in Git Credential Manger for Windows(GCM),

Control Panel->User Accounts -> Windows Credentials

Selecting rows where remainder (modulo) is 1 after division by 2?

Note: Disregard this answer, as I must have misunderstood the question.

select *
  from Table
  where len(ColName) mod 2 = 1

The exact syntax depends on what flavor of SQL you're using.

How to Avoid Response.End() "Thread was being aborted" Exception during the Excel file download

Use a special catch block for the exception of the Response.End() method

{
    ...
    context.Response.End(); //always throws an exception

}
catch (ThreadAbortException e)
{
    //this is special for the Response.end exception
}
catch (Exception e)
{
     context.Response.ContentType = "text/plain";
     context.Response.Write(e.Message);
}

Or just remove the Response.End() if your building a filehandler

C# 4.0: Convert pdf to byte[] and vice versa

Easiest way:

byte[] buffer;
using (Stream stream = new IO.FileStream("file.pdf"))
{
   buffer = new byte[stream.Length - 1];
   stream.Read(buffer, 0, buffer.Length);
}

using (Stream stream = new IO.FileStream("newFile.pdf"))
{
   stream.Write(buffer, 0, buffer.Length);
}

Or something along these lines...

How can I find the number of arguments of a Python function?

The previously accepted answer has been deprecated as of Python 3.0. Instead of using inspect.getargspec you should now opt for the Signature class which superseded it.

Creating a Signature for the function is easy via the signature function:

from inspect import signature

def someMethod(self, arg1, kwarg1=None):
    pass

sig = signature(someMethod)

Now, you can either view its parameters quickly by string it:

str(sig)  # returns: '(self, arg1, kwarg1=None)'

or you can also get a mapping of attribute names to parameter objects via sig.parameters.

params = sig.parameters 
print(params['kwarg1']) # prints: kwarg1=20

Additionally, you can call len on sig.parameters to also see the number of arguments this function requires:

print(len(params))  # 3

Each entry in the params mapping is actually a Parameter object that has further attributes making your life easier. For example, grabbing a parameter and viewing its default value is now easily performed with:

kwarg1 = params['kwarg1']
kwarg1.default # returns: None

similarly for the rest of the objects contained in parameters.


As for Python 2.x users, while inspect.getargspec isn't deprecated, the language will soon be :-). The Signature class isn't available in the 2.x series and won't be. So you still need to work with inspect.getargspec.

As for transitioning between Python 2 and 3, if you have code that relies on the interface of getargspec in Python 2 and switching to signature in 3 is too difficult, you do have the valuable option of using inspect.getfullargspec. It offers a similar interface to getargspec (a single callable argument) in order to grab the arguments of a function while also handling some additional cases that getargspec doesn't:

from inspect import getfullargspec

def someMethod(self, arg1, kwarg1=None):
    pass

args = getfullargspec(someMethod)

As with getargspec, getfullargspec returns a NamedTuple which contains the arguments.

print(args)
FullArgSpec(args=['self', 'arg1', 'kwarg1'], varargs=None, varkw=None, defaults=(None,), kwonlyargs=[], kwonlydefaults=None, annotations={})

How to check compiler log in sql developer?

control-shift-L should open the log(s) for you. this will by default be the messages log, but if you create the item that is creating the error the Compiler Log will show up (for me the box shows up in the bottom middle left).

if the messages log is the only log that shows up, simply re-execute the item that was causing the failure and the compiler log will show up

for instance, hit Control-shift-L then execute this

CREATE OR REPLACE FUNCTION TEST123() IS
BEGIN
VAR := 2;
end TEST123;

and you will see the message "Error(1,18): PLS-00103: Encountered the symbol ")" when expecting one of the following: current delete exists prior "

(You can also see this in "View--Log")

One more thing, if you are having a problem with a (function || package || procedure) if you do the coding via the SQL Developer interface (by finding the object in question on the connections tab and editing it the error will be immediately displayed (and even underlined at times)

How to secure RESTful web services?

HTTP Basic + HTTPS is one common method.

Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost."

I was getting this error as well, but on actual devices rather than the simulator. We noticed the error when accessing our heroku backend on HTTPS (gunicorn server), and doing POSTS with large bodys (anything over 64Kb). We use HTTP Basic Auth for authentication, and noticed the error was resolved by NOT using the didReceiveChallenge: delegate method on NSURLSession, but rather baking in the Authentication into the original request header via adding Authentiation: Basic <Base64Encoded UserName:Password>. This prevents the necessary 401 to trigger the didReceiveChallenge: delegate message, and the subsequent network connection lost.

How to prepend a string to a column value in MySQL?

  • UPDATE table_name SET Column1 = CONCAT('newtring', table_name.Column1) where 1
  • UPDATE table_name SET Column1 = CONCAT('newtring', table_name.Column2) where 1
  • UPDATE table_name SET Column1 = CONCAT('newtring', table_name.Column2, 'newtring2') where 1

We can concat same column or also other column of the table.

Change Schema Name Of Table In SQL

Be very very careful renaming objects in sql. You can cause dependencies to fail if you are not fully away with what you are doing. Having said that this works easily(too much so) for renaming things provided you have access proper on the environment:

exec sp_rename 'Nameofobject', 'ReNameofobject'

C++, How to determine if a Windows Process is running?

#include <cstdio>
#include <windows.h>
#include <tlhelp32.h>

/*!
\brief Check if a process is running
\param [in] processName Name of process to check if is running
\returns \c True if the process is running, or \c False if the process is not running
*/
bool IsProcessRunning(const wchar_t *processName)
{
    bool exists = false;
    PROCESSENTRY32 entry;
    entry.dwSize = sizeof(PROCESSENTRY32);

    HANDLE snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, NULL);

    if (Process32First(snapshot, &entry))
        while (Process32Next(snapshot, &entry))
            if (!wcsicmp(entry.szExeFile, processName))
                exists = true;

    CloseHandle(snapshot);
    return exists;
}

Redirect from asp.net web api post action

You can check this

[Route("Report/MyReport")]
public IHttpActionResult GetReport()
{

   string url = "https://localhost:44305/Templates/ReportPage.html";

   System.Uri uri = new System.Uri(url);

   return Redirect(uri);
}

How to use onResume()?

onResume() is one of the methods called throughout the activity lifecycle. onResume() is the counterpart to onPause() which is called anytime an activity is hidden from view, e.g. if you start a new activity that hides it. onResume() is called when the activity that was hidden comes back to view on the screen.

You're question asks abou what method is used to restart an activity. onCreate() is called when the activity is first created. In practice, most activities persist in the background through a series of onPause() and onResume() calls. An activity is only really "restarted" by onRestart() if it is first fully stopped by calling onStop() and then brought back to life. Thus if you are not actually stopping activities with onStop() it is most likley you will be using onResume().

Read the android doc in the above link to get a better understanding of the relationship between the different lifestyle methods. Regardless of which lifecycle method you end up using the general format is the same. You must override the standard method and include your code, i.e. what you want the activity to do at that point, in the commented section.

@Override
public void onResume(){
 //will be executed onResume
}

Unzip a file with php

Just use this:

  $master = $_GET["master"];
  system('unzip' $master.'.zip'); 

in your code $master is passed as a string, system will be looking for a file called $master.zip

  $master = $_GET["master"];
  system('unzip $master.zip'); `enter code here`

Const in JavaScript: when to use it and is it necessary?

You have great answers, but let's keep it simple.

const should be used when you have a defined constant (read as: it won't change during your program execution).

For example:

const pi = 3.1415926535

If you think that it is something that may be changed on later execution then use a var.

The practical difference, based on the example, is that with const you will always asume that pi will be 3.14[...], it's a fact.

If you define it as a var, it might be 3.14[...] or not.

For a more technical answer @Tibos is academically right.

Kubernetes Pod fails with CrashLoopBackOff

Pod is not started due to problem coming after initialization of POD.

Check and use command to get docker container of pod

docker ps -a | grep private-reg

Output will be information of docker container with id.

See docker logs:

docker logs -f <container id>

Why is my Button text forced to ALL CAPS on Lollipop?

Here's what I did in my values/themes.xml

    <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
        <item name="buttonStyle">@style/MyButton</item>
    </style>

    <style name="MyButton" parent="Widget.AppCompat.Button">
        <item name="android:textAllCaps">false</item>
    </style>

What is the difference between static_cast<> and C style casting?

C++ style casts are checked by the compiler. C style casts aren't and can fail at runtime.

Also, c++ style casts can be searched for easily, whereas it's really hard to search for c style casts.

Another big benefit is that the 4 different C++ style casts express the intent of the programmer more clearly.

When writing C++ I'd pretty much always use the C++ ones over the the C style.

Google Maps v3 - limit viewable area and zoom level

Good news. Starting from the version 3.35 of Maps JavaScript API, that was launched on February 14, 2019, you can use new restriction option in order to limit the viewport of the map.

According to the documentation

MapRestriction interface

A restriction that can be applied to the Map. The map's viewport will not exceed these restrictions.

source: https://developers.google.com/maps/documentation/javascript/reference/map#MapRestriction

So, now you just add restriction option during a map initialization and that it. Have a look at the following example that limits viewport to Switzerland

_x000D_
_x000D_
var map;
function initMap() {
  map = new google.maps.Map(document.getElementById('map'), {
    center: {lat: 46.818188, lng: 8.227512},
    minZoom: 7,
    maxZoom: 14,
    zoom: 7,
    restriction: {
      latLngBounds: {
        east: 10.49234,
        north: 47.808455,
        south: 45.81792,
        west: 5.95608
      },
      strictBounds: true
    },
  });
}
_x000D_
#map {
  height: 100%;
}
html, body {
  height: 100%;
  margin: 0;
  padding: 0;
}
_x000D_
<div id="map"></div>
<script src="https://maps.googleapis.com/maps/api/js?key=AIzaSyDztlrk_3CnzGHo7CFvLFqE_2bUKEq1JEU&callback=initMap" async defer></script>
_x000D_
_x000D_
_x000D_

I hope this helps!

Maintain/Save/Restore scroll position when returning to a ListView

I adopted the solution suggested by @(Kirk Woll), and it works for me. I have also seen in the Android source code for the "Contacts" app, that they use a similar technique. I would like to add some more details: On top on my ListActivity-derived class:

private static final String LIST_STATE = "listState";
private Parcelable mListState = null;

Then, some method overrides:

@Override
protected void onRestoreInstanceState(Bundle state) {
    super.onRestoreInstanceState(state);
    mListState = state.getParcelable(LIST_STATE);
}

@Override
protected void onResume() {
    super.onResume();
    loadData();
    if (mListState != null)
        getListView().onRestoreInstanceState(mListState);
    mListState = null;
}

@Override
protected void onSaveInstanceState(Bundle state) {
    super.onSaveInstanceState(state);
    mListState = getListView().onSaveInstanceState();
    state.putParcelable(LIST_STATE, mListState);
}

Of course "loadData" is my function to retrieve data from the DB and put it onto the list.

On my Froyo device, this works both when you change the phone orientation, and when you edit an item and go back to the list.

java.net.SocketException: Connection reset by peer: socket write error When serving a file

I face this problem but resolution is very simple. I am writing the 1 MB file in 1024 Byte Buffer causing this issue. To Understand refer code before and After Fix.

Code with Excepion

DataOutputStream dos = new DataOutputStream(s.getOutputStream());
        FileInputStream fis = new FileInputStream(file);
        byte[] buffer = new byte[1024];
        
        while (fis.read(buffer) > 0) {
            dos.write(buffer);
        }
    

After Fixes:

DataOutputStream dos = new DataOutputStream(s.getOutputStream());
        FileInputStream fis = new FileInputStream(file);
        byte[] buffer = new byte[102400];
        
        while (fis.read(buffer) > 0) {
            dos.write(buffer);
        }

    

Java: Calling a super method which calls an overridden method

Since the only way to avoid a method to get overriden is to use the keyword super, I've thought to move up the method2() from SuperClass to another new Base class and then call it from SuperClass:

class Base 
{
    public void method2()
    {
        System.out.println("superclass method2");
    }
}

class SuperClass extends Base
{
    public void method1()
    {
        System.out.println("superclass method1");
        super.method2();
    }
}

class SubClass extends SuperClass
{
    @Override
    public void method1()
    {
        System.out.println("subclass method1");
        super.method1();
    }

    @Override
    public void method2()
    {
        System.out.println("subclass method2");
    }
}

public class Demo 
{
    public static void main(String[] args) 
    {
        SubClass mSubClass = new SubClass();
        mSubClass.method1();
    }
}

Output:

subclass method1
superclass method1
superclass method2

Convert HTML5 into standalone Android App

You can use https://appery.io/ It is the same phonegap but in very convinient wrapper

How to hide a div from code (c#)

In the Html

<div id="AssignUniqueId" runat="server">.....BLAH......<div/>

In the code

public void Page_Load(object source, Event Args e)
{

   if(Session["Something"] == "ShowDiv")
      AssignUniqueId.Visible = true;
    else
      AssignUniqueID.Visible = false;
}

How to add an extra row to a pandas dataframe

Upcoming pandas 0.13 version will allow to add rows through loc on non existing index data. However, be aware that under the hood, this creates a copy of the entire DataFrame so it is not an efficient operation.

Description is here and this new feature is called Setting With Enlargement.

Shadow Effect for a Text in Android?

put these in values/colors.xml

<resources>
    <color name="light_font">#FBFBFB</color>
    <color name="grey_font">#ff9e9e9e</color>
    <color name="text_shadow">#7F000000</color>
    <color name="text_shadow_white">#FFFFFF</color>
</resources>

Then in your layout xml here are some example TextView's

Example of Floating text on Light with Dark shadow

<TextView android:id="@+id/txt_example1"
                  android:layout_width="wrap_content"
                  android:layout_height="wrap_content"
                  android:textSize="14sp"
                  android:textStyle="bold"
                  android:textColor="@color/light_font"
                  android:shadowColor="@color/text_shadow"
                  android:shadowDx="1"
                  android:shadowDy="1"
                  android:shadowRadius="2" />

enter image description here

Example of Etched text on Light with Dark shadow

<TextView android:id="@+id/txt_example2"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:textSize="14sp"
                android:textStyle="bold"
                android:textColor="@color/light_font"
                android:shadowColor="@color/text_shadow"
                android:shadowDx="-1"
                android:shadowDy="-1"
                android:shadowRadius="1" />

enter image description here

Example of Crisp text on Light with Dark shadow

<TextView android:id="@+id/txt_example3"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:textSize="14sp"
                android:textStyle="bold"
                android:textColor="@color/grey_font"
                android:shadowColor="@color/text_shadow_white"
                android:shadowDx="-2"
                android:shadowDy="-2"
                android:shadowRadius="1" />

enter image description here

Notice the positive and negative values... I suggest to play around with the colors/values yourself but ultimately you can adjust these settings to get the effect your looking for.

Check if selected dropdown value is empty using jQuery

You need to use .change() event as well as using # to target element by id:

$('#EventStartTimeMin').change(function() {
    if($(this).val()===""){ 
        console.log('empty');    
    }
});

Fiddle Demo

Parameter in like clause JPQL

I don't use named parameters for all queries. For example it is unusual to use named parameters in JpaRepository.

To workaround I use JPQL CONCAT function (this code emulate start with):

@Repository
public interface BranchRepository extends JpaRepository<Branch, String> {
    private static final String QUERY = "select b from Branch b"
       + " left join b.filial f"
       + " where f.id = ?1 and b.id like CONCAT(?2, '%')";
    @Query(QUERY)
    List<Branch> findByFilialAndBranchLike(String filialId, String branchCode);
}

I found this technique in excellent docs: http://openjpa.apache.org/builds/1.0.1/apache-openjpa-1.0.1/docs/manual/jpa_overview_query.html

Syntax behind sorted(key=lambda: ...)

Another usage of lambda and sorted is like the following:

Given the input array: people = [[7,0],[4,4],[7,1],[5,0],[6,1],[5,2]]

The line: people_sort = sorted(people, key = lambda x: (-x[0], x[1])) will give a people_sort list as [[7,0],[7,1],[6,1],[5,0],[5,2],[4,4]]

In this case, key=lambda x: (-x[0], x[1]) basically tells sorted to firstly sort the array based on the value of the first element of each of the instance(in descending order as the minus sign suggests), and then within the same subgroup, sort based on the second element of each of the instance(in ascending order as it is the default option).

Hope this is some useful information to you!

How to deal with the URISyntaxException

A space is encoded to %20 in URLs, and to + in forms submitted data (content type application/x-www-form-urlencoded). You need the former.

Using Guava:

dependencies {
     compile 'com.google.guava:guava:28.1-jre'
}

You can use UrlEscapers:

String encodedString = UrlEscapers.urlFragmentEscaper().escape(inputString);

Don't use String.replace, this would only encode the space. Use a library instead.

How to do a PUT request with curl?

Using the -X flag with whatever HTTP verb you want:

curl -X PUT -d arg=val -d arg2=val2 localhost:8080

This example also uses the -d flag to provide arguments with your PUT request.

HTTP 401 - what's an appropriate WWW-Authenticate header value?

When the user session times out, I send back an HTTP 204 status code. Note that the HTTP 204 status contains no content. On the client-side I do this:

xhr.send(null);
if (xhr.status == 204) 
    Reload();
else 
    dropdown.innerHTML = xhr.responseText;

Here is the Reload() function:

function Reload() {
    var oForm = document.createElement("form");
    document.body.appendChild(oForm);
    oForm.submit();
    }

How to list all `env` properties within jenkins pipeline job?

You can get all variables from your jenkins instance. Just visit:

  • ${jenkins_host}/env-vars.html
  • ${jenkins_host}/pipeline-syntax/globals

Hide element by class in pure Javascript

<script type="text/javascript">
        $(document).ready(function(){

                $('.appBanner').fadeOut('slow');

        });
    </script>

or

<script type="text/javascript">
        $(document).ready(function(){

                $('.appBanner').hide();

        });
    </script>

Ruby sleep or delay less than a second?

sleep(1.0/24.0)

As to your follow up question if that's the best way: No, you could get not-so-smooth framerates because the rendering of each frame might not take the same amount of time.

You could try one of these solutions:

  • Use a timer which fires 24 times a second with the drawing code.
  • Create as many frames as possible, create the motion based on the time passed, not per frame.

What's the purpose of SQL keyword "AS"?

The AS in this case is an optional keyword defined in ANSI SQL 92 to define a <<correlation name> ,commonly known as alias for a table.

<table reference> ::=
            <table name> [ [ AS ] <correlation name>
                [ <left paren> <derived column list> <right paren> ] ]
          | <derived table> [ AS ] <correlation name>
                [ <left paren> <derived column list> <right paren> ]
          | <joined table>

     <derived table> ::= <table subquery>

     <derived column list> ::= <column name list>

     <column name list> ::=
          <column name> [ { <comma> <column name> }... ]


     Syntax Rules

     1) A <correlation name> immediately contained in a <table refer-
        ence> TR is exposed by TR. A <table name> immediately contained
        in a <table reference> TR is exposed by TR if and only if TR
        does not specify a <correlation name>.

It seems a best practice NOT to use the AS keyword for table aliases as it is not supported by a number of commonly used databases.

mysql error 2005 - Unknown MySQL server host 'localhost'(11001)

The case is like :

 mysql connects will localhost when network is not up.
 mysql cannot connect when network is up.

You can try the following steps to diagnose and resolve the issue (my guess is that some other service is blocking port on which mysql is hosted):

  1. Disconnect the network.
  2. Stop mysql service (if windows, try from services.msc window)
  3. Connect to network.
  4. Try to start the mysql and see if it starts correctly.
  5. Check for system logs anyways to be sure that there is no error in starting mysql service.
  6. If all goes well try connecting.
  7. If fails, try to do a telnet localhost 3306 and see what output it shows.
  8. Try changing the port on which mysql is hosted, default 3306, you can change to some other port which is ununsed.

This should ideally resolve the issue you are facing.

Datetime current year and month in Python

Use:

from datetime import datetime

current_month = datetime.now().strftime('%m') // 02 //This is 0 padded
current_month_text = datetime.now().strftime('%h') // Feb
current_month_text = datetime.now().strftime('%B') // February

current_day = datetime.now().strftime('%d')   // 23 //This is also padded
current_day_text = datetime.now().strftime('%a')  // Fri
current_day_full_text = datetime.now().strftime('%A')  // Friday

current_weekday_day_of_today = datetime.now().strftime('%w') //5  Where 0 is Sunday and 6 is Saturday.

current_year_full = datetime.now().strftime('%Y')  // 2018
current_year_short = datetime.now().strftime('%y')  // 18 without century

current_second= datetime.now().strftime('%S') //53
current_minute = datetime.now().strftime('%M') //38
current_hour = datetime.now().strftime('%H') //16 like 4pm
current_hour = datetime.now().strftime('%I') // 04 pm

current_hour_am_pm = datetime.now().strftime('%p') // 4 pm

current_microseconds = datetime.now().strftime('%f') // 623596 Rarely we need.

current_timzone = datetime.now().strftime('%Z') // UTC, EST, CST etc. (empty string if the object is naive).

Reference: 8.1.7. strftime() and strptime() Behavior

Reference: strftime() and strptime() Behavior

The above things are useful for any date parsing, not only now or today. It can be useful for any date parsing.

e.g.
my_date = "23-02-2018 00:00:00"

datetime.strptime(str(my_date),'%d-%m-%Y %H:%M:%S').strftime('%Y-%m-%d %H:%M:%S+00:00')

datetime.strptime(str(my_date),'%d-%m-%Y %H:%M:%S').strftime('%m')

And so on...

Getting the length of two-dimensional array

which 3?

You've created a multi-dimentional array. nir is an array of int arrays; you've got two arrays of length three.

System.out.println(nir[0].length); 

would give you the length of your first array.

Also worth noting is that you don't have to initialize a multi-dimensional array as you did, which means all the arrays don't have to be the same length (or exist at all).

int nir[][] = new int[5][];
nir[0] = new int[5];
nir[1] = new int[3];
System.out.println(nir[0].length); // 5
System.out.println(nir[1].length); // 3
System.out.println(nir[2].length); // Null pointer exception

Spark SQL: apply aggregate functions to a list of columns

There are multiple ways of applying aggregate functions to multiple columns.

GroupedData class provides a number of methods for the most common functions, including count, max, min, mean and sum, which can be used directly as follows:

  • Python:

    df = sqlContext.createDataFrame(
        [(1.0, 0.3, 1.0), (1.0, 0.5, 0.0), (-1.0, 0.6, 0.5), (-1.0, 5.6, 0.2)],
        ("col1", "col2", "col3"))
    
    df.groupBy("col1").sum()
    
    ## +----+---------+-----------------+---------+
    ## |col1|sum(col1)|        sum(col2)|sum(col3)|
    ## +----+---------+-----------------+---------+
    ## | 1.0|      2.0|              0.8|      1.0|
    ## |-1.0|     -2.0|6.199999999999999|      0.7|
    ## +----+---------+-----------------+---------+
    
  • Scala

    val df = sc.parallelize(Seq(
      (1.0, 0.3, 1.0), (1.0, 0.5, 0.0),
      (-1.0, 0.6, 0.5), (-1.0, 5.6, 0.2))
    ).toDF("col1", "col2", "col3")
    
    df.groupBy($"col1").min().show
    
    // +----+---------+---------+---------+
    // |col1|min(col1)|min(col2)|min(col3)|
    // +----+---------+---------+---------+
    // | 1.0|      1.0|      0.3|      0.0|
    // |-1.0|     -1.0|      0.6|      0.2|
    // +----+---------+---------+---------+
    

Optionally you can pass a list of columns which should be aggregated

df.groupBy("col1").sum("col2", "col3")

You can also pass dictionary / map with columns a the keys and functions as the values:

  • Python

    exprs = {x: "sum" for x in df.columns}
    df.groupBy("col1").agg(exprs).show()
    
    ## +----+---------+
    ## |col1|avg(col3)|
    ## +----+---------+
    ## | 1.0|      0.5|
    ## |-1.0|     0.35|
    ## +----+---------+
    
  • Scala

    val exprs = df.columns.map((_ -> "mean")).toMap
    df.groupBy($"col1").agg(exprs).show()
    
    // +----+---------+------------------+---------+
    // |col1|avg(col1)|         avg(col2)|avg(col3)|
    // +----+---------+------------------+---------+
    // | 1.0|      1.0|               0.4|      0.5|
    // |-1.0|     -1.0|3.0999999999999996|     0.35|
    // +----+---------+------------------+---------+
    

Finally you can use varargs:

  • Python

    from pyspark.sql.functions import min
    
    exprs = [min(x) for x in df.columns]
    df.groupBy("col1").agg(*exprs).show()
    
  • Scala

    import org.apache.spark.sql.functions.sum
    
    val exprs = df.columns.map(sum(_))
    df.groupBy($"col1").agg(exprs.head, exprs.tail: _*)
    

There are some other way to achieve a similar effect but these should more than enough most of the time.

See also:

Excel VBA Run-time error '424': Object Required when trying to copy TextBox

The issue is with this line

 xlo.Worksheets(1).Cells(2, 2) = TextBox1.Text

You have the textbox defined at some other location which you are not using here. Excel is unable to find the textbox object in the current sheet while this textbox was defined in xlw.

Hence replace this with

 xlo.Worksheets(1).Cells(2, 2) = worksheets("xlw").TextBox1.Text 

JSLint is suddenly reporting: Use the function form of "use strict"

I think everyone missed the "suddenly" part of this question. Most likely, your .jshintrc has a syntax error, so it's not including the 'browser' line. Run it through a json validator to see where the error is.

SVN checkout the contents of a folder, not the folder itself

svn co svn://path destination

To specify current directory, use a "." for your destination directory:

svn checkout file:///home/landonwinters/svn/waterproject/trunk .

putting datepicker() on dynamically created elements - JQuery/JQueryUI

$( ".datepicker_recurring_start" ).each(function(){
    $(this).datepicker({
        dateFormat:"dd/mm/yy",
        yearRange: '2000:2012',
        changeYear: true,
        changeMonth: true
    });
});

Binding IIS Express to an IP Address

I think you can.

To do this you need to edit applicationhost.config file manually (edit bindingInformation '<ip-address>:<port>:<host-name>')

To start iisexpress, you need administrator privileges

including parameters in OPENQUERY

From the OPENQUERY documentation it states that:

OPENQUERY does not accept variables for its arguments.

See this article for a workaround.

UPDATE:

As suggested, I'm including the recommendations from the article below.

Pass Basic Values

When the basic Transact-SQL statement is known, but you have to pass in one or more specific values, use code that is similar to the following sample:

DECLARE @TSQL varchar(8000), @VAR char(2)
SELECT  @VAR = 'CA'
SELECT  @TSQL = 'SELECT * FROM OPENQUERY(MyLinkedServer,''SELECT * FROM pubs.dbo.authors WHERE state = ''''' + @VAR + ''''''')'
EXEC (@TSQL)

Pass the Whole Query

When you have to pass in the whole Transact-SQL query or the name of the linked server (or both), use code that is similar to the following sample:

DECLARE @OPENQUERY nvarchar(4000), @TSQL nvarchar(4000), @LinkedServer nvarchar(4000)
SET @LinkedServer = 'MyLinkedServer'
SET @OPENQUERY = 'SELECT * FROM OPENQUERY('+ @LinkedServer + ','''
SET @TSQL = 'SELECT au_lname, au_id FROM pubs..authors'')' 
EXEC (@OPENQUERY+@TSQL) 

Use the Sp_executesql Stored Procedure

To avoid the multi-layered quotes, use code that is similar to the following sample:

DECLARE @VAR char(2)
SELECT  @VAR = 'CA'
EXEC MyLinkedServer.master.dbo.sp_executesql
N'SELECT * FROM pubs.dbo.authors WHERE state = @state',
N'@state char(2)',
@VAR

How to enable Ad Hoc Distributed Queries

You may check the following command

sp_configure 'show advanced options', 1;
RECONFIGURE;
GO  --Added        
sp_configure 'Ad Hoc Distributed Queries', 1;
RECONFIGURE;
GO

SELECT a.*
FROM OPENROWSET('SQLNCLI', 'Server=Seattle1;Trusted_Connection=yes;',
     'SELECT GroupName, Name, DepartmentID
      FROM AdventureWorks2012.HumanResources.Department
      ORDER BY GroupName, Name') AS a;
GO

Or this documentation link

Calculating Distance between two Latitude and Longitude GeoCoordinates

This is an old question, nevertheless the answers did not satisfy me regarding to performance and optimization.

Here my optimized C# variant (distance in km, without variables and redundant calculations, very close to mathematical expression of Haversine Formular https://en.wikipedia.org/wiki/Haversine_formula).

Inspired by: https://rosettacode.org/wiki/Haversine_formula#C.23

public static class Haversine
{
    public static double Calculate(double lat1, double lon1, double lat2, double lon2)
    {
        double rad(double angle) => angle * 0.017453292519943295769236907684886127d; // = angle * Math.Pi / 180.0d
        double havf(double diff) => Math.Pow(Math.Sin(rad(diff) / 2d), 2); // = sin²(diff / 2)
        return 12745.6 * Math.Asin(Math.Sqrt(havf(lat2 - lat1) + Math.Cos(rad(lat1)) * Math.Cos(rad(lat2)) * havf(lon2 - lon1))); // earth radius 6.372,8?km x 2 = 12745.6
    }
}

Haversine Formular from Wikipedia

Check if a Windows service exists and delete in PowerShell

There's no harm in using the right tool for the job, I find running (from Powershell)

sc.exe \\server delete "MyService" 

the most reliable method that does not have many dependencies.

Python Requests library redirect new url

I think requests.head instead of requests.get will be more safe to call when handling url redirect,check the github issue here:

r = requests.head(url, allow_redirects=True)
print(r.url)

JQuery Ajax POST in Codeigniter

The question has already been answered but I thought I would also let you know that rather than using the native PHP $_POST I reccomend you use the CodeIgniter input class so your controller code would be

function post_action()
{   
    if($this->input->post('textbox') == "")
    {
        $message = "You can't send empty text";
    }
    else
    {
        $message = $this->input->post('textbox');
    }
    echo $message;
}

CSS Progress Circle

What about that?

HTML

<div class="chart" id="graph" data-percent="88"></div>

Javascript

var el = document.getElementById('graph'); // get canvas

var options = {
    percent:  el.getAttribute('data-percent') || 25,
    size: el.getAttribute('data-size') || 220,
    lineWidth: el.getAttribute('data-line') || 15,
    rotate: el.getAttribute('data-rotate') || 0
}

var canvas = document.createElement('canvas');
var span = document.createElement('span');
span.textContent = options.percent + '%';

if (typeof(G_vmlCanvasManager) !== 'undefined') {
    G_vmlCanvasManager.initElement(canvas);
}

var ctx = canvas.getContext('2d');
canvas.width = canvas.height = options.size;

el.appendChild(span);
el.appendChild(canvas);

ctx.translate(options.size / 2, options.size / 2); // change center
ctx.rotate((-1 / 2 + options.rotate / 180) * Math.PI); // rotate -90 deg

//imd = ctx.getImageData(0, 0, 240, 240);
var radius = (options.size - options.lineWidth) / 2;

var drawCircle = function(color, lineWidth, percent) {
        percent = Math.min(Math.max(0, percent || 1), 1);
        ctx.beginPath();
        ctx.arc(0, 0, radius, 0, Math.PI * 2 * percent, false);
        ctx.strokeStyle = color;
        ctx.lineCap = 'round'; // butt, round or square
        ctx.lineWidth = lineWidth
        ctx.stroke();
};

drawCircle('#efefef', options.lineWidth, 100 / 100);
drawCircle('#555555', options.lineWidth, options.percent / 100);

and CSS

div {
    position:relative;
    margin:80px;
    width:220px; height:220px;
}
canvas {
    display: block;
    position:absolute;
    top:0;
    left:0;
}
span {
    color:#555;
    display:block;
    line-height:220px;
    text-align:center;
    width:220px;
    font-family:sans-serif;
    font-size:40px;
    font-weight:100;
    margin-left:5px;
}

http://jsfiddle.net/Aapn8/3410/

Basic code was taken from Simple PIE Chart http://rendro.github.io/easy-pie-chart/

How do I set hostname in docker-compose?

Based on docker documentation: https://docs.docker.com/compose/compose-file/#/command

I simply put hostname: <string> in my docker-compose file.

E.g.:

[...]

lb01:
  hostname: at-lb01
  image: at-client-base:v1

[...]

and container lb01 picks up at-lb01 as hostname.

How to programmatically set drawableLeft on Android button?

For me, it worked:

button.setCompoundDrawablesWithIntrinsicBounds(com.example.project1.R.drawable.ic_launcher, 0, 0, 0);

How to install psycopg2 with "pip" on Python?

Psycopg2 Depends on Postgres Libraries. On Ubuntu You can use:

apt-get install libpq-dev

Then:

pip install psycopg2

Opening a .ipynb.txt File

go to cmd get into file directory and type jupyter notebook filename.ipynb in my case it open code editor and provide local host connection string copy that string and paste in any browser!done

Using floats with sprintf() in embedded C

Isn't something like this really easier:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char str[10];
float adc_read = 678.0123;

dtostrf( adc_read, 3, 4, temp );
sprintf(str,"adc_read = %10s \n", temp);
printf(temp);

Spring Boot - Error creating bean with name 'dataSource' defined in class path resource

This problem comes while you are running Test. Add dependency

testCompile group: 'com.h2database', name: 'h2', version: '1.4.197' 

Add folder resources under test source add file bootstrap.yml and provide content.

spring:
  datasource:
    type: com.zaxxer.hikari.HikariDataSource
    url: jdbc:h2:mem:TEST
    driver-class-name: org.h2.Driver
    username: username
    password: password
    hikari:
      idle-timeout: 10000

this will setup your data source.

Select from where field not equal to Mysql Php

You can use also

select * from tablename where column1 ='a' and column2!='b';

            

complex if statement in python

It is possible to write like this:

elif var1 in [80, 443] or 1024 < var1 < 65535

This way you check if var1 appears in that a list, then you make just 1 check, didn't repeat the "var1" one extra time, and looks clear:

if var1 in [80, 443] or 1024 < var1 < 65535: print 'good' else: print 'bad' ....:
good

How to fix java.net.SocketException: Broken pipe?

In our case we experienced this while performing a load test on our app server. The issue turned out that we need to add additional memory to our JVM because it was running out. This resolved the issue.

Try increasing the memory available to the JVM and or monitor the memory usage when you get those errors.

Switching the order of block elements with CSS

Update: Two lightweight CSS solutions:

Using flex, flex-flow and order:

Example1: Demo Fiddle

    body{
        display:flex;
        flex-flow: column;
    }
    #blockA{
        order:4;
    }
    #blockB{
        order:3;
    }
    #blockC{
        order:2;
    }

Alternatively, reverse the Y scale:

Example2: Demo Fiddle

body{
    -webkit-transform: scaleY(-1);
    transform: scaleY(-1);
}
div{
    -webkit-transform: scaleY(-1);
    transform: scaleY(-1);
}

Mongoose and multiple database in single node.js project

A bit optimized(for me atleast) solution. write this to a file db.js and require this to wherever required and call it with a function call and you are good to go.

   const MongoClient = require('mongodb').MongoClient;
    async function getConnections(url,db){
        return new Promise((resolve,reject)=>{
            MongoClient.connect(url, { useUnifiedTopology: true },function(err, client) {
                if(err) { console.error(err) 
                    resolve(false);
                }
                else{
                    resolve(client.db(db));
                }
            })
        });
    }

    module.exports = async function(){
        let dbs      = [];
        dbs['db1']     = await getConnections('mongodb://localhost:27017/','db1');
        dbs['db2']     = await getConnections('mongodb://localhost:27017/','db2');
        return dbs;
    };

How to convert a HTMLElement to a string

You can get the 'outer-html' by cloning the element, adding it to an empty,'offstage' container, and reading the container's innerHTML.

This example takes an optional second parameter.

Call document.getHTML(element, true) to include the element's descendents.

document.getHTML= function(who, deep){
    if(!who || !who.tagName) return '';
    var txt, ax, el= document.createElement("div");
    el.appendChild(who.cloneNode(false));
    txt= el.innerHTML;
    if(deep){
        ax= txt.indexOf('>')+1;
        txt= txt.substring(0, ax)+who.innerHTML+ txt.substring(ax);
    }
    el= null;
    return txt;
}

Java Long primitive type maximum limit

It will overflow and wrap around to Long.MIN_VALUE.

Its not too likely though. Even if you increment 1,000,000 times per second it will take about 300,000 years to overflow.

Android: Getting "Manifest merger failed" error after updating to a new version of gradle

The answer are accepted but one thing you could also do is to define the libraries from your project structure. What you can do is :

  1. Comment all the libraries in which problem is coming
  2. Goto your project structure
  3. Add libraries from there and it'll sync automatically and the problem goes off.
  4. If problem persists try looking from the error log that what library is it demanding after following all the above 3 steps.

What happens is the predefined libraries as off now now I'm taking the appcompat:26.0.0-alpha1 it uses the older version of the things when you add something new and tries to resolve it with the old stuffs. When you add it from your project structure, it'll add the same thing but with the new stuffs to resolve it. Your problem would be resolved.

Django, creating a custom 500/404 error page

Under your main views.py add your own custom implementation of the following two views, and just set up the templates 404.html and 500.html with what you want to display.

With this solution, no custom code needs to be added to urls.py

Here's the code:

from django.shortcuts import render_to_response
from django.template import RequestContext


def handler404(request, *args, **argv):
    response = render_to_response('404.html', {},
                                  context_instance=RequestContext(request))
    response.status_code = 404
    return response


def handler500(request, *args, **argv):
    response = render_to_response('500.html', {},
                                  context_instance=RequestContext(request))
    response.status_code = 500
    return response

Update

handler404 and handler500 are exported Django string configuration variables found in django/conf/urls/__init__.py. That is why the above config works.

To get the above config to work, you should define the following variables in your urls.py file and point the exported Django variables to the string Python path of where these Django functional views are defined, like so:

# project/urls.py

handler404 = 'my_app.views.handler404'
handler500 = 'my_app.views.handler500'

Update for Django 2.0

Signatures for handler views were changed in Django 2.0: https://docs.djangoproject.com/en/2.0/ref/views/#error-views

If you use views as above, handler404 will fail with message:

"handler404() got an unexpected keyword argument 'exception'"

In such case modify your views like this:

def handler404(request, exception, template_name="404.html"):
    response = render_to_response(template_name)
    response.status_code = 404
    return response

Using `window.location.hash.includes` throws “Object doesn't support property or method 'includes'” in IE11

This question and its answers led me to my own solution (with help from SO), though some say you shouldn't tamper with native prototypes:

  // IE does not support .includes() so I'm making my own:
  String.prototype.doesInclude=function(needle){
    return this.substring(needle) != -1;
  }

Then I just replaced all .includes() with .doesInclude() and my problem was solved.

update package.json version automatically

Just in case if you want to do this using an npm package semver link

let fs = require('fs');
let semver = require('semver');

if (fs.existsSync('./package.json')) {
    var package = require('./package.json');
    let currentVersion = package.version;
    let type = process.argv[2];
    if (!['major', 'minor', 'patch'].includes(type)) {
        type = 'patch';
    }

    let newVersion = semver.inc(package.version, type);
    package.version = newVersion;
    fs.writeFileSync('./package.json', JSON.stringify(package, null, 2));

    console.log('Version updated', currentVersion, '=>', newVersion);
}

package.json should look like,

{
  "name": "versioning",
  "version": "0.0.0",
  "description": "Update version in package.json using npm script",
  "main": "version.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "version": "node version.js"
  },
  "author": "Bhadresh Arya",
  "license": "ISC",
  "dependencies": {
    "semver": "^7.3.2"
  }
}

just pass major, minor, patch argument with npm run version. Default will be patch.

example: npm run version or npm run verison patch or npm run verison minor or npm run version major

Git Repo

How do I make a JAR from a .java file?

Perhaps the most beginner-friendly way to compile a JAR from your Java code is to use an IDE (integrated development environment; essentially just user-friendly software for development) like Netbeans or Eclipse.

  • Install and set-up an IDE. Here is the latest version of Eclipse.
  • Create a project in your IDE and put your Java files inside of the project folder.
  • Select the project in the IDE and export the project as a JAR. Double check that the appropriate java files are selected when exporting.

You can always do this all very easily with the command line. Make sure that you are in the same directory as the files targeted before executing a command such as this:

javac YourApp.java
jar -cf YourJar.jar YourApp.class

...changing "YourApp" and "YourJar" to the proper names of your files, respectively.

Two versions of python on linux. how to make 2.7 the default

Enter the command

which python

//output:
/usr/bin/python

cd /usr/bin
ls -l

Here you can see something like this

lrwxrwxrwx 1 root   root            9 Mar  7 17:04  python -> python2.7

your default python2.7 is soft linked to the text 'python'

So remove the softlink python

sudo rm -r python

then retry the above command

ls -l

you can see the softlink is removed

-rwxr-xr-x 1 root   root      3670448 Nov 12 20:01  python2.7

Then create a new softlink for python3.6

ln -s /usr/bin/python3.6 python

Then try the command python in terminal

//output:
Python 3.6.7 (default, Oct 22 2018, 11:32:17) 
[GCC 8.2.0] on linux

Type help, copyright, credits or license for more information.

link_to image tag. how to add class to a tag

Best will be:

link_to image_tag("Search.png", :border => 0, :alt => '', :title => ''), pages_search_path, :class => 'dock-item'

Access VBA | How to replace parts of a string with another string

Use Access's VBA function Replace(text, find, replacement):

Dim result As String

result = Replace("Some sentence containing Avenue in it.", "Avenue", "Ave")

Get a specific bit from byte

Easy. Use a bitwise AND to compare your number with the value 2^bitNumber, which can be cheaply calculated by bit-shifting.

//your black magic
var bit = (b & (1 << bitNumber-1)) != 0;

EDIT: To add a little more detail because there are a lot of similar answers with no explanation:

A bitwise AND compares each number, bit-by-bit, using an AND join to produce a number that is the combination of bits where both the first bit and second bit in that place were set. Here's the logic matrix of AND logic in a "nibble" that shows the operation of a bitwise AND:

  0101
& 0011
  ----
  0001 //Only the last bit is set, because only the last bit of both summands were set

In your case, we compare the number you passed with a number that has only the bit you want to look for set. Let's say you're looking for the fourth bit:

  11010010
& 00001000
  --------
  00000000 //== 0, so the bit is not set

  11011010
& 00001000
  --------
  00001000 //!= 0, so the bit is set

Bit-shifting, to produce the number we want to compare against, is exactly what it sounds like: take the number, represented as a set of bits, and shift those bits left or right by a certain number of places. Because these are binary numbers and so each bit is one greater power-of-two than the one to its right, bit-shifting to the left is equivalent to doubling the number once for each place that is shifted, equivalent to multiplying the number by 2^x. In your example, looking for the fourth bit, we perform:

       1 (2^0) << (4-1) ==        8 (2^3)
00000001       << (4-1) == 00001000

Now you know how it's done, what's going on at the low level, and why it works.

How can I right-align text in a DataGridView column?

I know this is old, but for those surfing this question, the answer by MUG4N will align all columns that use the same defaultcellstyle. I'm not using autogeneratecolumns so that is not acceptable. Instead I used:

e.Column.DefaultCellStyle = new DataGridViewCellStyle(e.Column.DefaultCellStyle);
e.Column.DefaultCellStyle.Alignment = DataGridViewContentAlignment.MiddleRight;

In this case e is from:

Grd_ColumnAdded(object sender, DataGridViewColumnEventArgs e)  

Using number_format method in Laravel

If you are using Eloquent, in your model put:

public function getPriceAttribute($price)
{
    return $this->attributes['price'] = sprintf('U$ %s', number_format($price, 2));
}

Where getPriceAttribute is your field on database. getSomethingAttribute.

How to get the contents of a webpage in a shell variable?

There is the wget command or the curl.

You can now use the file you downloaded with wget. Or you can handle a stream with curl.


Resources :

When to use a View instead of a Table?

Views are handy when you need to select from several tables, or just to get a subset of a table.

You should design your tables in such a way that your database is well normalized (minimum duplication). This can make querying somewhat difficult.

Views are a bit of separation, allowing you to view the data in the tables differently than they are stored.

SQL query to find record with ID not in another table

Use LEFT JOIN

SELECT  a.*
FROM    table1 a
            LEFT JOIN table2 b
                on a.ID = b.ID
WHERE   b.id IS NULL

SVG rounded corner

As referenced in my answer to Applying rounded corners to paths/polygons, I have written a routine in javascript for generically rounding corners of SVG paths, with examples, here: http://plnkr.co/edit/kGnGGyoOCKil02k04snu.

It will work independently from any stroke effects you may have. To use, include the rounding.js file from the Plnkr and call the function like so:

roundPathCorners(pathString, radius, useFractionalRadius)

The result will be the rounded path.

The results look like this:

SVG Path Rounding Examples

How to create a numpy array of arbitrary length strings?

You can do so by creating an array of dtype=object. If you try to assign a long string to a normal numpy array, it truncates the string:

>>> a = numpy.array(['apples', 'foobar', 'cowboy'])
>>> a[2] = 'bananas'
>>> a
array(['apples', 'foobar', 'banana'], 
      dtype='|S6')

But when you use dtype=object, you get an array of python object references. So you can have all the behaviors of python strings:

>>> a = numpy.array(['apples', 'foobar', 'cowboy'], dtype=object)
>>> a
array([apples, foobar, cowboy], dtype=object)
>>> a[2] = 'bananas'
>>> a
array([apples, foobar, bananas], dtype=object)

Indeed, because it's an array of objects, you can assign any kind of python object to the array:

>>> a[2] = {1:2, 3:4}
>>> a
array([apples, foobar, {1: 2, 3: 4}], dtype=object)

However, this undoes a lot of the benefits of using numpy, which is so fast because it works on large contiguous blocks of raw memory. Working with python objects adds a lot of overhead. A simple example:

>>> a = numpy.array(['abba' for _ in range(10000)])
>>> b = numpy.array(['abba' for _ in range(10000)], dtype=object)
>>> %timeit a.copy()
100000 loops, best of 3: 2.51 us per loop
>>> %timeit b.copy()
10000 loops, best of 3: 48.4 us per loop

Read file data without saving it in Flask

In case we want to dump the in memory file to disk. This code can be used

  if isinstanceof(obj,SpooledTemporaryFile):
    obj.rollover()

$('body').on('click', '.anything', function(){})

You should use $(document). It is a function trigger for any click event in the document. Then inside you can use the jquery on("click","body *",somefunction), where the second argument specifies which specific element to target. In this case every element inside the body.

$(document).on('click','body *',function(){
    //  $(this) = your current element that clicked.
    // additional code
});

How to get MAC address of your machine using a C program?

You need to iterate over all the available interfaces on your machine, and use ioctl with SIOCGIFHWADDR flag to get the mac address. The mac address will be obtained as a 6-octet binary array. You also want to skip the loopback interface.

#include <sys/ioctl.h>
#include <net/if.h> 
#include <unistd.h>
#include <netinet/in.h>
#include <string.h>

int main()
{
    struct ifreq ifr;
    struct ifconf ifc;
    char buf[1024];
    int success = 0;

    int sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
    if (sock == -1) { /* handle error*/ };

    ifc.ifc_len = sizeof(buf);
    ifc.ifc_buf = buf;
    if (ioctl(sock, SIOCGIFCONF, &ifc) == -1) { /* handle error */ }

    struct ifreq* it = ifc.ifc_req;
    const struct ifreq* const end = it + (ifc.ifc_len / sizeof(struct ifreq));

    for (; it != end; ++it) {
        strcpy(ifr.ifr_name, it->ifr_name);
        if (ioctl(sock, SIOCGIFFLAGS, &ifr) == 0) {
            if (! (ifr.ifr_flags & IFF_LOOPBACK)) { // don't count loopback
                if (ioctl(sock, SIOCGIFHWADDR, &ifr) == 0) {
                    success = 1;
                    break;
                }
            }
        }
        else { /* handle error */ }
    }

    unsigned char mac_address[6];

    if (success) memcpy(mac_address, ifr.ifr_hwaddr.sa_data, 6);
}

How does the FetchMode work in Spring Data JPA

The fetch mode will only work when selecting the object by id i.e. using entityManager.find(). Since Spring Data will always create a query, the fetch mode configuration will have no use to you. You can either use dedicated queries with fetch joins or use entity graphs.

When you want best performance, you should select only the subset of the data you really need. To do this, it is generally recommended to use a DTO approach to avoid unnecessary data to be fetched, but that usually results in quite a lot of error prone boilerplate code, since you need define a dedicated query that constructs your DTO model via a JPQL constructor expression.

Spring Data projections can help here, but at some point you will need a solution like Blaze-Persistence Entity Views which makes this pretty easy and has a lot more features in it's sleeve that will come in handy! You just create a DTO interface per entity where the getters represent the subset of data you need. A solution to your problem could look like this

@EntityView(Identified.class)
public interface IdentifiedView {
    @IdMapping
    Integer getId();
}

@EntityView(Identified.class)
public interface UserView extends IdentifiedView {
    String getName();
}

@EntityView(Identified.class)
public interface StateView extends IdentifiedView {
    String getName();
}

@EntityView(Place.class)
public interface PlaceView extends IdentifiedView {
    UserView getAuthor();
    CityView getCity();
}

@EntityView(City.class)
public interface CityView extends IdentifiedView {
    StateView getState();
}

public interface PlaceRepository extends JpaRepository<Place, Long>, PlaceRepositoryCustom {
    PlaceView findById(int id);
}

public interface UserRepository extends JpaRepository<User, Long> {
    List<UserView> findAllByOrderByIdAsc();
    UserView findById(int id);
}

public interface CityRepository extends JpaRepository<City, Long>, CityRepositoryCustom {    
    CityView findById(int id);
}

Disclaimer, I'm the author of Blaze-Persistence, so I might be biased.

How to auto import the necessary classes in Android Studio with shortcut?

Go on the missing declaration with cursor and press alt+enter enter image description here

MIME types missing in IIS 7 for ASP.NET - 404.17

Fix:

I chose the "ISAPI & CGI Restrictions" after clicking the server name (not the site name) in IIS Manager, and right clicked the "ASP.NET v4.0.30319" lines and chose "Allow".

After turning on ASP.NET from "Programs and Features > Turn Windows features on or off", you must install ASP.NET from the Windows command prompt. The MIME types don't ever show up, but after doing this command, I noticed these extensions showed up under the IIS web site "Handler Mappings" section of IIS Manager.

C:\>cd C:\Windows\Microsoft.NET\Framework64\v4.0.30319

C:\Windows\Microsoft.NET\Framework64\v4.0.30319>dir aspnet_reg*
 Volume in drive C is Windows
 Volume Serial Number is 8EE6-5DD0

 Directory of C:\Windows\Microsoft.NET\Framework64\v4.0.30319

03/18/2010  08:23 PM            19,296 aspnet_regbrowsers.exe
03/18/2010  08:23 PM            36,696 aspnet_regiis.exe
03/18/2010  08:23 PM           102,232 aspnet_regsql.exe
               3 File(s)        158,224 bytes
               0 Dir(s)  34,836,508,672 bytes free

C:\Windows\Microsoft.NET\Framework64\v4.0.30319>aspnet_regiis.exe -i
Start installing ASP.NET (4.0.30319).
.....
Finished installing ASP.NET (4.0.30319).

C:\Windows\Microsoft.NET\Framework64\v4.0.30319>

However, I still got this error. But if you do what I mentioned for the "Fix", this will go away.

HTTP Error 404.2 - Not Found
The page you are requesting cannot be served because of the ISAPI and CGI Restriction list settings on the Web server.

How to handle notification when app in background in Firebase

I feel like all the responses are incomplete but all of them have something that you need to process a notification that have data when your app is in background.

Follow these steps and you will be able to process your notifications when your app is in background.

1.Add an intent-filter like this:

<activity android:name=".MainActivity">
      <intent-filter>
           <action android:name=".MainActivity" />
           <category android:name="android.intent.category.DEFAULT" />
      </intent-filter>
</activity>

to an activity that you want to process the notification data.

  1. Send notifications with the next format:

    { 
     "notification" : {
            "click_action" : ".MainActivity", 
            "body" : "new Symulti update !", 
            "title" : "new Symulti update !", 
            "icon" : "ic_notif_symulti" }, 
     "data": { ... },
     "to" : "c9Vaa3ReGdk:APA91bH-AuXgg3lDN2WMcBrNhJZoFtYF9" }
    

The key here is add

"click_action" : ".MainActivity"

where .MainActivity is the activity with the intent-filter that you added in step 1.

  1. Get "data" info from notification in the onCreate of ".MainActivity":

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //get notification data info
        Bundle bundle = getIntent().getExtras();
        if (bundle != null) {
           //bundle must contain all info sent in "data" field of the notification
        }
    }
    

And that should be all you need to do. I hope this helps somebody :)

Open a file with Notepad in C#

System.Diagnostics.Process.Start( "notepad.exe", "text.txt");

How to install Ruby 2.1.4 on Ubuntu 14.04

There is a PPA with up-to-date versions of Ruby 2.x for Ubuntu 12.04+:

$ sudo apt-add-repository ppa:brightbox/ruby-ng
$ sudo apt-get update
$ sudo apt-get install ruby2.4

$ ruby -v
ruby 2.4.1p111 (2017-03-22 revision 58053) [x86_64-linux-gnu]

error: expected primary-expression before ')' token (C)

A function call needs to be performed with objects. You are doing the equivalent of this:

// function declaration/definition
void foo(int) {}

// function call
foo(int); // wat!??

i.e. passing a type where an object is required. This makes no sense in C or C++. You need to be doing

int i = 42;
foo(i);

or

foo(42);

Determining if an Object is of primitive type

public class CheckPrimitve {
    public static void main(String[] args) {
        int i = 3;
        Object o = i;
        System.out.println(o.getClass().getSimpleName().equals("Integer"));
        Field[] fields = o.getClass().getFields();
        for(Field field:fields) {
            System.out.println(field.getType());
        }
    }
}  

Output:
true
int
int
class java.lang.Class
int

is there a css hack for safari only NOT chrome?

At the end I use a little JavaScript to achieve it:

if (navigator.vendor.startsWith('Apple'))
    document.documentElement.classList.add('on-apple');

then in my CSS to target Apple browser engine the selector will be:

.on-apple .my-class{
    ...
}

How to change font size on part of the page in LaTeX?

http://en.wikibooks.org/wiki/LaTeX/Formatting

use \alltt environment instead. Then set size using the same commands as outside verbatim environment.

How to get a path to a resource in a Java JAR file

if netclient.p is inside a JAR file, it won't have a path because that file is located inside other file. in that case, the best path you can have is really file:/path/to/jarfile/bot.jar!/config/netclient.p.

Html5 Full screen video

You can use html5 video player which has full screen playback option. This is a very good html5 player to have a look.
http://sublimevideo.net/

Printing Python version in output

import platform
print(platform.python_version())

This prints something like

3.7.2

Removing the remembered login and password list in SQL Server Management Studio

For those looking for the SSMS 2012 solution... see this answer:

Remove cached login 2012

Essentially, in 2012 you can delete the server from the server list dropdown which clears all cached logins for that server.

Works also in v17 (build 14.x).

Transpose a data frame

Take advantage of as.matrix:

# keep the first column 
names <-  df.aree[,1]

# Transpose everything other than the first column
df.aree.T <- as.data.frame(as.matrix(t(df.aree[,-1])))

# Assign first column as the column names of the transposed dataframe
colnames(df.aree.T) <- names

How can I force Python's file.write() to use the same newline format in Windows as in Linux ("\r\n" vs. "\n")?

You need to open the file in binary mode i.e. wb instead of w. If you don't, the end of line characters are auto-converted to OS specific ones.

Here is an excerpt from Python reference about open().

The default is to use text mode, which may convert '\n' characters to a platform-specific representation on writing and back on reading.

Char array in a struct - incompatible assignment?

Or you could just use dynamic allocation, e.g.:

struct name {
  char *first;
  char *last;
};

struct name sara;
sara.first = "Sara";
sara.last = "Black";
printf("first: %s, last: %s\n", sara.first, sara.last);

How to show text in combobox when no item selected?

Use the insert method of the combobox to insert the "Please select item" in to 0 index,

comboBox1.Items.Insert(0, "Please select any value");

and add all the items to the combobox after the first index. In the form load set

comboBox1.SelectedIndex = 0;

EDIT:

In form load write the text in to the comboBox1.Text by hardcoding

comboBox1.Text = "Please, select any value";

and in the TextChanged event of the comboBox1 write the following code

 private void comboBox1_TextChanged(object sender, EventArgs e)
        {
            if (comboBox1.SelectedIndex < 0)
            {
                comboBox1.Text = "Please, select any value";
            }
            else
            {
                comboBox1.Text = comboBox1.SelectedText;
            }
        }

Notice: Array to string conversion in

Store the Value of $_SESSION['username'] into a variable such as $username

$username=$_SESSION['username'];

$get = @mysql_query("SELECT money FROM players WHERE username = 
 '$username'");

it should work!

What is the difference between Release and Debug modes in Visual Studio?

Debug and Release are just labels for different solution configurations. You can add others if you want. A project I once worked on had one called "Debug Internal" which was used to turn on the in-house editing features of the application. You can see this if you go to Configuration Manager... (it's on the Build menu). You can find more information on MSDN Library under Configuration Manager Dialog Box.

Each solution configuration then consists of a bunch of project configurations. Again, these are just labels, this time for a collection of settings for your project. For example, our C++ library projects have project configurations called "Debug", "Debug_Unicode", "Debug_MT", etc.

The available settings depend on what type of project you're building. For a .NET project, it's a fairly small set: #defines and a few other things. For a C++ project, you get a much bigger variety of things to tweak.

In general, though, you'll use "Debug" when you want your project to be built with the optimiser turned off, and when you want full debugging/symbol information included in your build (in the .PDB file, usually). You'll use "Release" when you want the optimiser turned on, and when you don't want full debugging information included.

Change the Bootstrap Modal effect

If you take a look at the bootstraps fade class used with the modal window you will find, that all it does, is to set the opacity value to 0 and adds a transition for the opacity rule.

Whenever you launch a modal the in class is added and will change the opacity to a value of 1.

Knowing that you can easily build your own fade-scale class.

Here is an example.

_x000D_
_x000D_
@import url("https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css");_x000D_
_x000D_
.fade-scale {_x000D_
  transform: scale(0);_x000D_
  opacity: 0;_x000D_
  -webkit-transition: all .25s linear;_x000D_
  -o-transition: all .25s linear;_x000D_
  transition: all .25s linear;_x000D_
}_x000D_
_x000D_
.fade-scale.in {_x000D_
  opacity: 1;_x000D_
  transform: scale(1);_x000D_
}
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.0/jquery.min.js"></script>_x000D_
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>_x000D_
_x000D_
<!-- Button trigger modal -->_x000D_
<button type="button" class="btn btn-primary btn-lg" data-toggle="modal" data-target="#myModal">_x000D_
  Launch demo modal_x000D_
</button>_x000D_
_x000D_
<!-- Modal -->_x000D_
<div class="modal fade-scale" id="myModal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel">_x000D_
  <div class="modal-dialog" role="document">_x000D_
    <div class="modal-content">_x000D_
      <div class="modal-header">_x000D_
        <button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">&times;</span></button>_x000D_
        <h4 class="modal-title" id="myModalLabel">Modal title</h4>_x000D_
      </div>_x000D_
      <div class="modal-body">_x000D_
        ..._x000D_
      </div>_x000D_
      <div class="modal-footer">_x000D_
        <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>_x000D_
        <button type="button" class="btn btn-primary">Save changes</button>_x000D_
      </div>_x000D_
    </div>_x000D_
  </div>_x000D_
</div>
_x000D_
_x000D_
_x000D_

-- UPDATE --

This answer is getting more up votes lately so i figured i add an update to show how easy it is to customize the BS modal in and out animations with the help of the great Animate.css library by
Daniel Eden.

All that needs to be done is to include the stylesheet to your <head></head> section. Now you simply need to add the animated class, plus one of the entrance classes of the library to the modal element.

<div class="modal animated fadeIn" id="myModal" tabindex="-1" role="dialog" ...>
  ...
</div>

But there is also a way to add an out animation to the modal window and since the library has a bunch of cool animations that will make an element disappear, why not use them. :)

To use them you will need to toggle the classes on the modal element, so it is actually better to call the modal window via JavaScript, which is described here.

You will also need to listen for some of the modal events to know when it's time to add or remove the classes from the modal element. The events being fired are described here.

To trigger a custom out animation you can't use the data-dismiss="modal" attribute on a button inside the modal window that's suppose to close the modal. You can simply add your own attribute like data-custom-dismiss="modal" and use that to call the $('selector').modal.('hide') method on it.

Here is an example that shows all the different possibilities.

_x000D_
_x000D_
/* -------------------------------------------------------_x000D_
| This first part can be ignored, it is just getting_x000D_
| all the different entrance and exit classes of the_x000D_
| animate-config.json file from the github repo._x000D_
--------------------------------------------------------- */_x000D_
_x000D_
var animCssConfURL = 'https://api.github.com/repos/daneden/animate.css/contents/animate-config.json';_x000D_
var selectIn = $('#animation-in-types');_x000D_
var selectOut = $('#animation-out-types');_x000D_
var getAnimCSSConfig = function ( url ) { return $.ajax( { url: url, type: 'get', dataType: 'json' } ) };_x000D_
var decode = function ( data ) {_x000D_
  var bin = Uint8Array.from( atob( data['content'] ), function( char ) { return char.charCodeAt( 0 ) } );_x000D_
  var bin2Str = String.fromCharCode.apply( null, bin );_x000D_
  return JSON.parse( bin2Str )_x000D_
}_x000D_
var buildSelect = function ( which, name, animGrp ) {_x000D_
  var grp = $('<optgroup></optgroup>');_x000D_
  grp.attr('label', name);_x000D_
  $.each(animGrp, function ( idx, animType ) {_x000D_
    var opt = $('<option></option>')_x000D_
    opt.attr('value', idx)_x000D_
    opt.text(idx)_x000D_
    grp.append(opt);_x000D_
  })_x000D_
  which.append(grp) _x000D_
}_x000D_
getAnimCSSConfig( animCssConfURL )_x000D_
  .done (function ( data ) {_x000D_
  var animCssConf = decode ( data );_x000D_
  $.each(animCssConf, function(name, animGrp) {_x000D_
    if ( /_entrances/.test(name) ) {_x000D_
      buildSelect(selectIn, name, animGrp);_x000D_
    }_x000D_
    if ( /_exits/.test(name) ) {_x000D_
      buildSelect(selectOut, name, animGrp);_x000D_
    }_x000D_
  })_x000D_
})_x000D_
_x000D_
_x000D_
/* -------------------------------------------------------_x000D_
| Here is were the fun begins._x000D_
--------------------------------------------------------- */_x000D_
_x000D_
var modalBtn = $('button');_x000D_
var modal = $('#myModal');_x000D_
var animInClass = "";_x000D_
var animOutClass = "";_x000D_
_x000D_
modalBtn.on('click', function() {_x000D_
  animInClass = selectIn.find('option:selected').val();_x000D_
  animOutClass = selectOut.find('option:selected').val();_x000D_
  if ( animInClass == '' || animOutClass == '' ) {_x000D_
    alert("Please select an in and out animation type.");_x000D_
  } else {_x000D_
    modal.addClass(animInClass);_x000D_
    modal.modal({backdrop: false});_x000D_
  }_x000D_
})_x000D_
_x000D_
modal.on('show.bs.modal', function () {_x000D_
  var closeModalBtns = modal.find('button[data-custom-dismiss="modal"]');_x000D_
  closeModalBtns.one('click', function() {_x000D_
    modal.on('webkitAnimationEnd oanimationend msAnimationEnd animationend', function( evt ) {_x000D_
      modal.modal('hide')_x000D_
    });_x000D_
    modal.removeClass(animInClass).addClass(animOutClass);_x000D_
  })_x000D_
})_x000D_
_x000D_
modal.on('hidden.bs.modal', function ( evt ) {_x000D_
  var closeModalBtns = modal.find('button[data-custom-dismiss="modal"]');_x000D_
  modal.removeClass(animOutClass)_x000D_
  modal.off('webkitAnimationEnd oanimationend msAnimationEnd animationend')_x000D_
  closeModalBtns.off('click')_x000D_
})
_x000D_
@import url('https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css');_x000D_
@import url('https://cdnjs.cloudflare.com/ajax/libs/animate.css/3.5.2/animate.css');_x000D_
_x000D_
select, button:not([data-custom-dismiss="modal"]) {_x000D_
  margin: 10px 0;_x000D_
  width: 220px;_x000D_
}
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>_x000D_
_x000D_
<div class="container">_x000D_
  <div class="row">_x000D_
    <div class="col-xs-4 col-xs-offset-4 col-sm-4 col-sm-offset-4">_x000D_
      <select id="animation-in-types">_x000D_
        <option value="" selected>Choose animation-in type</option>_x000D_
      </select>_x000D_
    </div>_x000D_
  </div>_x000D_
  <div class="row">_x000D_
    <div class="col-xs-4 col-xs-offset-4 col-sm-4 col-sm-offset-4">_x000D_
      <select id="animation-out-types">_x000D_
        <option value="" selected>Choose animation-out type</option>_x000D_
      </select>_x000D_
    </div>_x000D_
  </div>_x000D_
  <div class="row">_x000D_
    <div class="col-xs-4 col-xs-offset-4 col-sm-4 col-sm-offset-4">_x000D_
      <button class="btn btn-default">Open Modal</button>_x000D_
    </div>_x000D_
  </div>_x000D_
</div>_x000D_
_x000D_
<!-- Modal -->_x000D_
<div class="modal animated" id="myModal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel">_x000D_
  <div class="modal-dialog" role="document">_x000D_
    <div class="modal-content">_x000D_
      <div class="modal-header">_x000D_
        <button type="button" class="close" data-custom-dismiss="modal" aria-label="Close"><span aria-hidden="true">&times;</span></button>_x000D_
        <h4 class="modal-title" id="myModalLabel">Modal title</h4>_x000D_
      </div>_x000D_
      <div class="modal-body">_x000D_
        ..._x000D_
      </div>_x000D_
      <div class="modal-footer">_x000D_
        <button type="button" class="btn btn-default" data-custom-dismiss="modal">Close</button>_x000D_
      </div>_x000D_
    </div>_x000D_
  </div>_x000D_
</div>
_x000D_
_x000D_
_x000D_

How do I loop through a date range?

Here are my 2 cents in 2020.

Enumerable.Range(0, (endDate - startDate).Days + 1)
.ToList()
.Select(a => startDate.AddDays(a));

Passing Arrays to Function in C++

firstarray and secondarray are converted to a pointer to int, when passed to printarray().

printarray(int arg[], ...) is equivalent to printarray(int *arg, ...)

However, this is not specific to C++. C has the same rules for passing array names to a function.

Conditionally formatting cells if their value equals any value of another column

I unable to comment on the top answer, but Excel actually lets you do this without adding the ugly conditional logic.

Conditional formatting is automatically applied to any input that isn't an error, so you can achieve the same effect as:

=NOT(ISERROR(MATCH(A1,$B$1:$B$1000,0)))

With this:

= MATCH(A1,$B$1:$B$1000,0)))

If the above is applied to your data, A1 will be formatted if it matches any cell in $B$1:$B$1000, as any non-match will return an error.

ffprobe or avprobe not found. Please install one

Compiling the last answers into one:

If you're on Windows, use chocolatey:

choco install ffmpeg

If you are on Mac, use Brew:

brew install ffmpeg

If you are on a Debian Linux distribution, use apt:

sudo apt-get install ffmpeg

And make sure Youtube-dl is updated:

youtube-dl -U

Multiple select in Visual Studio?

In the Visual Studio Shift+Alt+. / Shift+Alt+,

  • Shift+Alt+. - match caret;
  • Shift+Alt+, - remove previous caret;

Same function as on VSCode Ctrl+D.

Much more setting Tool - Options - Environment - keyboard. Next in the Show commands containing enter Edit..

Also, can use keyboard schema Visual Studio Code. Available for Visual Studio 2017

For conclusion, nice link Visual Studio All keyboard shortcuts

List all devices, partitions and volumes in Powershell

Run command:

Get-PsDrive -PsProvider FileSystem

For more info see:

What are the new features in C++17?

Language features:

Templates and Generic Code

Lambda

Attributes

Syntax cleanup

Cleaner multi-return and flow control

  • Structured bindings

    • Basically, first-class std::tie with auto
    • Example:
      • const auto [it, inserted] = map.insert( {"foo", bar} );
      • Creates variables it and inserted with deduced type from the pair that map::insert returns.
    • Works with tuple/pair-likes & std::arrays and relatively flat structs
    • Actually named structured bindings in standard
  • if (init; condition) and switch (init; condition)

    • if (const auto [it, inserted] = map.insert( {"foo", bar} ); inserted)
    • Extends the if(decl) to cases where decl isn't convertible-to-bool sensibly.
  • Generalizing range-based for loops

    • Appears to be mostly support for sentinels, or end iterators that are not the same type as begin iterators, which helps with null-terminated loops and the like.
  • if constexpr

    • Much requested feature to simplify almost-generic code.

Misc

Library additions:

Data types

Invoke stuff

File System TS v1

New algorithms

  • for_each_n

  • reduce

  • transform_reduce

  • exclusive_scan

  • inclusive_scan

  • transform_exclusive_scan

  • transform_inclusive_scan

  • Added for threading purposes, exposed even if you aren't using them threaded

Threading

(parts of) Library Fundamentals TS v1 not covered above or below

Container Improvements

Smart pointer changes

Other std datatype improvements:

Misc

Traits

Deprecated

Isocpp.org has has an independent list of changes since C++14; it has been partly pillaged.

Naturally TS work continues in parallel, so there are some TS that are not-quite-ripe that will have to wait for the next iteration. The target for the next iteration is C++20 as previously planned, not C++19 as some rumors implied. C++1O has been avoided.

Initial list taken from this reddit post and this reddit post, with links added via googling or from the above isocpp.org page.

Additional entries pillaged from SD-6 feature-test list.

clang's feature list and library feature list are next to be pillaged. This doesn't seem to be reliable, as it is C++1z, not C++17.

these slides had some features missing elsewhere.

While "what was removed" was not asked, here is a short list of a few things ((mostly?) previous deprecated) that are removed in C++17 from C++:

Removed:

There were rewordings. I am unsure if these have any impact on code, or if they are just cleanups in the standard:

Papers not yet integrated into above:

  • P0505R0 (constexpr chrono)

  • P0418R2 (atomic tweaks)

  • P0512R0 (template argument deduction tweaks)

  • P0490R0 (structured binding tweaks)

  • P0513R0 (changes to std::hash)

  • P0502R0 (parallel exceptions)

  • P0509R1 (updating restrictions on exception handling)

  • P0012R1 (make exception specifications be part of the type system)

  • P0510R0 (restrictions on variants)

  • P0504R0 (tags for optional/variant/any)

  • P0497R0 (shared ptr tweaks)

  • P0508R0 (structured bindings node handles)

  • P0521R0 (shared pointer use count and unique changes?)

Spec changes:

Further reference:

How to use jquery or ajax to update razor partial view in c#/asp.net for a MVC project

You can also use Url.Action for the path instead like so:

$.ajax({
        url: "@Url.Action("Holiday", "Calendar", new { area = "", year= (val * 1) + 1 })",                
        type: "GET",           
        success: function (partialViewResult) {            
            $("#refTable").html(partialViewResult);
        }
    });

How an 'if (A && B)' statement is evaluated?

yes, if( (A) && (B) ) will fail on the first clause, if (A) evaluates false.

this applies to any language btw, not just C derivatives. For threaded and parallel processing this is a different story ;)

Convert integer to string Jinja

The OP needed to cast as string outside the {% set ... %}. But if that not your case you can do:

{% set curYear = 2013 | string() %}

Note that you need the parenthesis on that jinja filter.

If you're concatenating 2 variables, you can also use the ~ custom operator.

How do I set a checkbox in razor view?

I did it using Razor , works for me

Razor Code

@Html.CheckBox("CashOnDelivery", CashOnDelivery) (This is a bit or bool value) Razor don't support nullable bool
@Html.CheckBox("OnlinePayment", OnlinePayment)

C# Code

 var CashOnDelivery = Convert.ToBoolean(Collection["CashOnDelivery"].Contains("true")?true:false);
 var OnlinePayment = Convert.ToBoolean(Collection["OnlinePayment"].Contains("true") ? true : false);

Getting RSA private key from PEM BASE64 Encoded private key file

The problem you'll face is that there's two types of PEM formatted keys: PKCS8 and SSLeay. It doesn't help that OpenSSL seems to use both depending on the command:

The usual openssl genrsa command will generate a SSLeay format PEM. An export from an PKCS12 file with openssl pkcs12 -in file.p12 will create a PKCS8 file.

The latter PKCS8 format can be opened natively in Java using PKCS8EncodedKeySpec. SSLeay formatted keys, on the other hand, can not be opened natively.

To open SSLeay private keys, you can either use BouncyCastle provider as many have done before or Not-Yet-Commons-SSL have borrowed a minimal amount of necessary code from BouncyCastle to support parsing PKCS8 and SSLeay keys in PEM and DER format: http://juliusdavies.ca/commons-ssl/pkcs8.html. (I'm not sure if Not-Yet-Commons-SSL will be FIPS compliant)

Key Format Identification

By inference from the OpenSSL man pages, key headers for two formats are as follows:

PKCS8 Format

Non-encrypted: -----BEGIN PRIVATE KEY-----
Encrypted: -----BEGIN ENCRYPTED PRIVATE KEY-----

SSLeay Format

-----BEGIN RSA PRIVATE KEY-----

(These seem to be in contradiction to other answers but I've tested OpenSSL's output using PKCS8EncodedKeySpec. Only PKCS8 keys, showing ----BEGIN PRIVATE KEY----- work natively)

C function that counts lines in file

You're opening a file, then passing the file pointer to a function that only wants a file name to open the file itself. You can simplify your call to;

void main(void)
{
  printf("LINES: %d\n",countlines("Test.txt"));
}

EDIT: You're changing the question around so it's very hard to answer; at first you got your change to main() wrong, you forgot that the first parameter is argc, so it crashed. Now you have the problem of;

if (fp == NULL);   // <-- note the extra semicolon that is the only thing 
                   //     that runs conditionally on the if 
  return 0;        // Always runs and returns 0

which will always return 0. Remove that extra semicolon, and you should get a reasonable count.

Can I store images in MySQL

You'll need to save as a blob, LONGBLOB datatype in mysql will work.

Ex:

CREATE TABLE 'test'.'pic' (
    'idpic' INTEGER UNSIGNED NOT NULL AUTO_INCREMENT,
    'caption' VARCHAR(45) NOT NULL,
    'img' LONGBLOB NOT NULL,
  PRIMARY KEY ('idpic')
)

As others have said, its a bad practice but it can be done. Not sure if this code would scale well, though.

Choosing bootstrap vs material design

As far as I know you can use all mentioned technologies separately or together. It's up to you. I think you look at the problem from the wrong angle. Material Design is just the way particular elements of the page are designed, behave and put together. Material Design provides great UI/UX, but it relies on the graphic layout (HTML/CSS) rather than JS (events, interactions).

On the other hand, AngularJS and Bootstrap are front-end frameworks that can speed up your development by saving you from writing tons of code. For example, you can build web app utilizing AngularJS, but without Material Design. Or You can build simple HTML5 web page with Material Design without AngularJS or Bootstrap. Finally you can build web app that uses AngularJS with Bootstrap and with Material Design. This is the best scenario. All technologies support each other.

  1. Bootstrap = responsive page
  2. AngularJS = MVC
  3. Material Design = great UI/UX

You can check awesome material design components for AngularJS:

https://material.angularjs.org


enter image description here

Demo: https://material.angularjs.org/latest/demo/ enter image description here

How to set javascript variables using MVC4 with Razor

I use a very simple function to solve syntax errors in body of JavaScript codes that mixed with Razor codes ;)

function n(num){return num;}

var nonID = n(@nonProID);
var proID= n(@proID);

Adding system header search path to Xcode

Though this question has an answer, I resolved it differently when I had the same issue. I had this issue when I copied folders with the option Create Folder references; then the above solution of adding the folder to the build_path worked. But when the folder was added using the Create groups for any added folder option, the headers were picked up automatically.

Auto submit form on page load

Try this On window load submit your form.

window.onload = function(){
  document.forms['member_signup'].submit();
}

ToList().ForEach in Linq

employees.ToList().ForEach(
     emp=>
     {
          collection.AddRange(emp.Departments);
          emp.Departments.ToList().ForEach(u=>u.SomeProperty = null);
     });

How to jump back to NERDTree from file in tab?

Since it's not mentioned and it's really helpful:

ctrl-wp

which I memorize as go to the previously selected window.

It works as a there and back command. After having opened a new file from the tree in a new window press ctrl-wp to switch back to the NERDTree and use it again to return to your previous window.

PS: it is worth to mention that ctrl-wp is actually documented as go to the preview window (see: :help preview-window and :help ctrl-w).

It is also the only keystroke which works to switch inside and explore the COC preview documentation window.

BSTR to std::string (std::wstring) and vice versa

Simply pass the BSTR directly to the wstring constructor, it is compatible with a wchar_t*:

BSTR btest = SysAllocString(L"Test");
assert(btest != NULL);
std::wstring wtest(btest);
assert(0 == wcscmp(wtest.c_str(), btest));

Converting BSTR to std::string requires a conversion to char* first. That's lossy since BSTR stores a utf-16 encoded Unicode string. Unless you want to encode in utf-8. You'll find helper methods to do this, as well as manipulate the resulting string, in the ICU library.

Path to Powershell.exe (v 2.0)

I believe it's in C:\Windows\System32\WindowsPowershell\v1.0\. In order to confuse the innocent, MS kept it in a directory labeled "v1.0". Running this on Windows 7 and checking the version number via $Host.Version (Determine installed PowerShell version) shows it's 2.0.

Another option is type $PSVersionTable at the command prompt. If you are running v2.0, the output will be:

Name                           Value
----                           -----
CLRVersion                     2.0.50727.4927
BuildVersion                   6.1.7600.16385
PSVersion                      2.0
WSManStackVersion              2.0
PSCompatibleVersions           {1.0, 2.0}
SerializationVersion           1.1.0.1
PSRemotingProtocolVersion      2.1

If you're running version 1.0, the variable doesn't exist and there will be no output.

Localization PowerShell version 1.0, 2.0, 3.0, 4.0:

  • 64 bits version: C:\Windows\System32\WindowsPowerShell\v1.0\
  • 32 bits version: C:\Windows\SysWOW64\WindowsPowerShell\v1.0\

How to change default text color using custom theme?

Check if your activity layout overrides the theme, look for your activity layout located at layout/*your_activity*.xml and look for TextView that contains android:textColor="(some hex code") something like that on activity layout, and remove it. Then run your code again.

json and empty array

The first version is a null object while the second is an Array object with zero elements.

Null may mean here for example that no location is available for that user, no location has been requested or that some restrictions apply. Hard to tell with no reference to the API.

Sequence Permission in Oracle

To grant a permission:

grant select on schema_name.sequence_name to user_or_role_name;

To check which permissions have been granted

select * from all_tab_privs where TABLE_NAME = 'sequence_name'

How do I start an activity from within a Fragment?

You should do it with getActivity().startActivity(myIntent)

How do I "select Android SDK" in Android Studio?

You are using Google API SDK. This for some reason doesn't work anymore with the embedded java JDK / JRE.

Follow the solution I described here and set Android Studio JDK path to your local JDK (ex. OpenJDK)

Why can't variables be declared in a switch statement?

Consider:

switch(val)
{
case VAL:
   int newVal = 42;
default:
   int newVal = 23;
}

In the absence of break statements, sometimes newVal gets declared twice, and you don't know whether it does until runtime. My guess is that the limitation is because of this kind of confusion. What would the scope of newVal be? Convention would dictate that it would be the whole of the switch block (between the braces).

I'm no C++ programmer, but in C:

switch(val) {
    int x;
    case VAL:
        x=1;
}

Works fine. Declaring a variable inside a switch block is fine. Declaring after a case guard is not.

How do you decrease navbar height in Bootstrap 3?

Instead of <nav class="navbar ... use <nav class="navbar navbar-xs...

and add these 3 line of css

.navbar-xs { min-height:28px; height: 28px; }
.navbar-xs .navbar-brand{ padding: 0px 12px;font-size: 16px;line-height: 28px; }
.navbar-xs .navbar-nav > li > a {  padding-top: 0px; padding-bottom: 0px; line-height: 28px; }

Output :

enter image description here

setting y-axis limit in matplotlib

One thing you can do is to set your axis range by yourself by using matplotlib.pyplot.axis.

matplotlib.pyplot.axis

from matplotlib import pyplot as plt
plt.axis([0, 10, 0, 20])

0,10 is for x axis range. 0,20 is for y axis range.

or you can also use matplotlib.pyplot.xlim or matplotlib.pyplot.ylim

matplotlib.pyplot.ylim

plt.ylim(-2, 2)
plt.xlim(0,10)

Perform commands over ssh with Python

Asking User to enter the command as per the device they are logging in.
The below code is validated by PEP8online.com.

import paramiko
import xlrd
import time

ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
loc = ('/Users/harshgow/Documents/PYTHON_WORK/labcred.xlsx')
wo = xlrd.open_workbook(loc)
sheet = wo.sheet_by_index(0)
Host = sheet.cell_value(0, 1)
Port = int(sheet.cell_value(3, 1))
User = sheet.cell_value(1, 1)
Pass = sheet.cell_value(2, 1)

def details(Host, Port, User, Pass):
    time.sleep(2)
    ssh.connect(Host, Port, User, Pass)
    print('connected to ip ', Host)
    stdin, stdout, stderr = ssh.exec_command("")
    x = input('Enter the command:')
    stdin.write(x)
    stdin.write('\n')
    print('success')

details(Host, Port, User, Pass)

How to align two elements on the same line without changing HTML

Change your css as below

#element1 {float:left;margin-right:10px;} 
#element2 {float:left;} 

Here is the JSFiddle http://jsfiddle.net/a4aME/

Inheritance and init method in Python

Since you don't call Num.__init__ , the field "n1" never gets created. Call it and then it will be there.

What is the difference between pull and clone in git?

In laymen language we can say:

  • Clone: Get a working copy of the remote repository.
  • Pull: I am working on this, please get me the new changes that may be updated by others.

Comments in Android Layout xml

Unbelievably, in 2019 with Android studio 3.3 (I don't know exact version, at least 3.3), it is possible to use double slash comment to xml.

But if you use double slash comment in xml, IDE shows warning.

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    // this works

    /* this works too */

    /*
    multi line comment
    multi line comment
    */

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World! yeah"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

Can I open a dropdownlist using jQuery

It is not possible for javascript to "click" on an element (u can trigger the attached onclick event, but you can't literally click it)

To view all the items in the list, make the list a multiple list and increase its size, like such:

<select id="countries" multiple="multiple" size="10">
<option value="1">Country</option>
</select>

Debugging PHP Mail() and/or PHPMailer

It looks like the class.phpmailer.php file is corrupt. I would download the latest version and try again.

I've always used phpMailer's SMTP feature:

$mail->IsSMTP();
$mail->Host = "localhost";

And if you need debug info:

$mail->SMTPDebug  = 2; // enables SMTP debug information (for testing)
                       // 1 = errors and messages
                       // 2 = messages only

Find p-value (significance) in scikit-learn LinearRegression

The code in elyase's answer https://stackoverflow.com/a/27928411/4240413 does not actually work. Notice that sse is a scalar, and then it tries to iterate through it. The following code is a modified version. Not amazingly clean, but I think it works more or less.

class LinearRegression(linear_model.LinearRegression):

    def __init__(self,*args,**kwargs):
        # *args is the list of arguments that might go into the LinearRegression object
        # that we don't know about and don't want to have to deal with. Similarly, **kwargs
        # is a dictionary of key words and values that might also need to go into the orginal
        # LinearRegression object. We put *args and **kwargs so that we don't have to look
        # these up and write them down explicitly here. Nice and easy.

        if not "fit_intercept" in kwargs:
            kwargs['fit_intercept'] = False

        super(LinearRegression,self).__init__(*args,**kwargs)

    # Adding in t-statistics for the coefficients.
    def fit(self,x,y):
        # This takes in numpy arrays (not matrices). Also assumes you are leaving out the column
        # of constants.

        # Not totally sure what 'super' does here and why you redefine self...
        self = super(LinearRegression, self).fit(x,y)
        n, k = x.shape
        yHat = np.matrix(self.predict(x)).T

        # Change X and Y into numpy matricies. x also has a column of ones added to it.
        x = np.hstack((np.ones((n,1)),np.matrix(x)))
        y = np.matrix(y).T

        # Degrees of freedom.
        df = float(n-k-1)

        # Sample variance.     
        sse = np.sum(np.square(yHat - y),axis=0)
        self.sampleVariance = sse/df

        # Sample variance for x.
        self.sampleVarianceX = x.T*x

        # Covariance Matrix = [(s^2)(X'X)^-1]^0.5. (sqrtm = matrix square root.  ugly)
        self.covarianceMatrix = sc.linalg.sqrtm(self.sampleVariance[0,0]*self.sampleVarianceX.I)

        # Standard erros for the difference coefficients: the diagonal elements of the covariance matrix.
        self.se = self.covarianceMatrix.diagonal()[1:]

        # T statistic for each beta.
        self.betasTStat = np.zeros(len(self.se))
        for i in xrange(len(self.se)):
            self.betasTStat[i] = self.coef_[0,i]/self.se[i]

        # P-value for each beta. This is a two sided t-test, since the betas can be 
        # positive or negative.
        self.betasPValue = 1 - t.cdf(abs(self.betasTStat),df)

Python spacing and aligning strings

As of Python 3.6, we have a better option, f-strings!

>>> print(f"{'Location: ' + location:<25} Revision: {revision}")
>>> print(f"{'District: ' + district:<25} Date: {date}")
>>> print(f"{'User: ' + user:<25} Time: {time}")

Output:

Location: 10-10-10-10     Revision: 1
District: Tower           Date: May 16, 2012
User: LOD                 Time: 10:15

Since everything within the curly brackets is evaluated at runtime, we can enter both the string 'Location: ' concatenated with the variable location. Using :<25 places the entire concatenated string into a box 25 characters long, and the < designates that you want it left aligned. That way, the second column always starts after those 25 characters reserved for the first column.

Another benefit here is that you don't have to count the characters in your format string. Using 25 will work for all of them, provided that 25 is long enough to contain all of the characters in your left column.

https://realpython.com/python-f-strings/ explains the benefits of f-strings over previous options. https://medium.com/@NirantK/best-of-python3-6-f-strings-41f9154983e explains how to use <, >, and ^ for left, right, and center aligned.

How do I create and store md5 passwords in mysql

To increase security even more, You can have md5 encryption along with two different salt strings, one static salt defined in php file and then one more randomly generated unique salt for each password record.

Here is how you can generate salt, md5 string and store:

    $unique_salt_string = hash('md5', microtime()); 
    $password = hash('md5', $_POST['password'].'static_salt'.$unique_salt_string);
    $query = "INSERT INTO users (username,password,salt) VALUES('bob','".$password."', '".$unique_salt_string."');

Now you have a static salt, which is valid for all your passwords, that is stored in the .php file. Then, at registration execution, you generate a unique hash for that specific password.

This all ends up with: two passwords that are spelled exactly the same, will have two different hashes. The unique hash is stored in the database along with the current id. If someone grab the database, they will have every single unique salt for every specific password. But what they don't have is your static salt, which make things a lot harder for every "hacker" out there.

This is how you check the validity of your password on login.php for example:

     $user = //username input;
     $db_query = mysql_query("SELECT salt FROM users WHERE username='$user'");
     while($salt = mysql_fetch_array($db_query)) {
            $password = hash('md5',$_POST['userpassword'].'static_salt'.$salt[salt]);
}

This method is very powerful and secure. If you want to use sha512 encryption, just to put that inside the hash function instead of md5 in above code.

How to call a method in another class of the same package?

If you define the method as static you can use it without instantiating the class first, but then you also dont have the object variables available for use.

public class Foo {
   public static String Bar() {
      return "bla";
   }
}

In that case you could call it with Foo.Bar().

Multiplication on command line terminal

Yes, you can use bash's built-in Arithmetic Expansion $(( )) to do some simple maths

$ echo "$((5 * 5))"
25

Check the Shell Arithmetic section in the Bash Reference Manual for a complete list of operators.

For sake of completeness, as other pointed out, if you need arbitrary precision, bc or dc would be better.

Django Rest Framework File Upload

I'd like to write another option that I feel is cleaner and easier to maintain. We'll be using the defaultRouter to add CRUD urls for our viewset and we'll add one more fixed url specifying the uploader view within the same viewset.

**** views.py 

from rest_framework import viewsets, serializers
from rest_framework.decorators import action, parser_classes
from rest_framework.parsers import JSONParser, MultiPartParser
from rest_framework.response import Response
from rest_framework_csv.parsers import CSVParser
from posts.models import Post
from posts.serializers import PostSerializer     


class PostsViewSet(viewsets.ModelViewSet):

    queryset = Post.objects.all()
    serializer_class = PostSerializer 
    parser_classes = (JSONParser, MultiPartParser, CSVParser)


    @action(detail=False, methods=['put'], name='Uploader View', parser_classes=[CSVParser],)
    def uploader(self, request, filename, format=None):
        # Parsed data will be returned within the request object by accessing 'data' attr  
        _data = request.data

        return Response(status=204)

Project's main urls.py

**** urls.py 

from rest_framework import routers
from posts.views import PostsViewSet


router = routers.DefaultRouter()
router.register(r'posts', PostsViewSet)

urlpatterns = [
    url(r'^posts/uploader/(?P<filename>[^/]+)$', PostsViewSet.as_view({'put': 'uploader'}), name='posts_uploader')
    url(r'^', include(router.urls), name='root-api'),
    url('admin/', admin.site.urls),
]

.- README.

The magic happens when we add @action decorator to our class method 'uploader'. By specifying "methods=['put']" argument, we are only allowing PUT requests; perfect for file uploading.

I also added the argument "parser_classes" to show you can select the parser that will parse your content. I added CSVParser from the rest_framework_csv package, to demonstrate how we can accept only certain type of files if this functionality is required, in my case I'm only accepting "Content-Type: text/csv". Note: If you're adding custom Parsers, you'll need to specify them in parsers_classes in the ViewSet due the request will compare the allowed media_type with main (class) parsers before accessing the uploader method parsers.

Now we need to tell Django how to go to this method and where can be implemented in our urls. That's when we add the fixed url (Simple purposes). This Url will take a "filename" argument that will be passed in the method later on. We need to pass this method "uploader", specifying the http protocol ('PUT') in a list to the PostsViewSet.as_view method.

When we land in the following url

 http://example.com/posts/uploader/ 

it will expect a PUT request with headers specifying "Content-Type" and Content-Disposition: attachment; filename="something.csv".

curl -v -u user:pass http://example.com/posts/uploader/ --upload-file ./something.csv --header "Content-type:text/csv"

count distinct values in spreadsheet

This works if you just want the count of unique values in e.g. the following range

=counta(unique(B4:B21))

iOS 7 status bar back to iOS 6 default style in iPhone app?

Try this simple method....

Step 1:To change in single viewController

[[UIApplication sharedApplication] setStatusBarStyle: UIStatusBarStyleBlackOpaque];

Step 2: To change in whole application

info.plist
      ----> Status Bar Style
                  --->UIStatusBarStyle to UIStatusBarStyleBlackOpaque

Step 3: Also add this in each viewWillAppear to adjust statusbar height for iOS7

    [[UIApplication sharedApplication]setStatusBarStyle:UIStatusBarStyleLightContent];
    if ([[UIDevice currentDevice].systemVersion floatValue] >= 7) {
        CGRect frame = [UIScreen mainScreen].bounds;
        frame.origin.y+=20.0;
        frame.size.height-= 20.0;
        self.view.frame = frame;
        [self.view layoutIfNeeded];
    }

jasmine: Async callback was not invoked within timeout specified by jasmine.DEFAULT_TIMEOUT_INTERVAL

Works after removing the scope reference and the function arguments:

"use strict";

describe("Request Notification Channel", function() {
    var requestNotificationChannel, rootScope;

    beforeEach(function() {
        module("messageAppModule");

        inject(function($injector, _requestNotificationChannel_) {
            rootScope = $injector.get("$rootScope");
            requestNotificationChannel = _requestNotificationChannel_;
        })
        spyOn(rootScope, "$broadcast");
    });


    it("should broadcast delete message notification with provided params", function() {
        requestNotificationChannel.deleteMessage(1, 4);
        expect(rootScope.$broadcast).toHaveBeenCalledWith("_DELETE_MESSAGE_", { id: 1, index: 4} );
    });
});

Spring @Autowired and @Qualifier

The @Qualifier annotation is used to resolve the autowiring conflict, when there are multiple beans of same type.

The @Qualifier annotation can be used on any class annotated with @Component or on methods annotated with @Bean. This annotation can also be applied on constructor arguments or method parameters.

Ex:-

public interface Vehicle {
     public void start();
     public void stop();
}

There are two beans, Car and Bike implements Vehicle interface

@Component(value="car")
public class Car implements Vehicle {

     @Override
     public void start() {
           System.out.println("Car started");
     }

     @Override
     public void stop() {
           System.out.println("Car stopped");
     }
 }

@Component(value="bike")
public class Bike implements Vehicle {

     @Override
     public void start() {
          System.out.println("Bike started");
     }

     @Override
     public void stop() {
          System.out.println("Bike stopped");
     }
}

Injecting Bike bean in VehicleService using @Autowired with @Qualifier annotation. If you didn't use @Qualifier, it will throw NoUniqueBeanDefinitionException.

@Component
public class VehicleService {

    @Autowired
    @Qualifier("bike")
    private Vehicle vehicle;

    public void service() {
         vehicle.start();
         vehicle.stop();
    }
}

Reference:- @Qualifier annotation example

How to get the Mongo database specified in connection string in C#

With version 1.7 of the official 10gen driver, this is the current (non-obsolete) API:

const string uri = "mongodb://localhost/mydb";
var client = new MongoClient(uri);
var db = client.GetServer().GetDatabase(new MongoUrl(uri).DatabaseName);
var collection = db.GetCollection("mycollection");

How to view method information in Android Studio?

Yes, you can. Go to File -> Settings -> Editor -> Show quick documentation on mouse move

Or, in Mac OS X, go to Android Studio - > Preferences -> Editor - > General > Show quick documentation on mouse move.

How to store Java Date to Mysql datetime with JPA

Annotate your field (or getter) with @Temporal(TemporalType.TIMESTAMP), like this:

public class MyEntity {
    ...
    @Temporal(TemporalType.TIMESTAMP)
    private java.util.Date myDate;
    ...
}

That should do the trick.

C# How to determine if a number is a multiple of another?

followings programs will execute,"one number is multiple of another" in

#include<stdio.h>
int main
{
int a,b;
printf("enter any two number\n");
scanf("%d%d",&a,&b);
if (a%b==0)
printf("this is  multiple number");
else if (b%a==0);
printf("this is multiple number");
else
printf("this is not multiple number");
return 0;
}

One command to create a directory and file inside it linux command

For this purpose, you can create your own function. For example:

$ echo 'mkfile() { mkdir -p "$(dirname "$1")" && touch "$1" ;  }' >> ~/.bashrc
$ source ~/.bashrc
$ mkfile ./fldr1/fldr2/file.txt

Explanation:

  • Insert the function to the end of ~/.bashrc file using the echo command
  • The -p flag is for creating the nested folders, such as fldr2
  • Update the ~/.bashrc file with the source command
  • Use the mkfile function to create the file

Fastest way to iterate over all the chars in a String

FIRST UPDATE: Before you try this ever in a production environment (not advised), read this first: http://www.javaspecialists.eu/archive/Issue237.html Starting from Java 9, the solution as described won't work anymore, because now Java will store strings as byte[] by default.

SECOND UPDATE: As of 2016-10-25, on my AMDx64 8core and source 1.8, there is no difference between using 'charAt' and field access. It appears that the jvm is sufficiently optimized to inline and streamline any 'string.charAt(n)' calls.

THIRD UPDATE: As of 2020-09-07, on my Ryzen 1950-X 16 core and source 1.14, 'charAt1' is 9 times slower than field access and 'charAt2' is 4 times slower than field access. Field access is back as the clear winner. Note than the program will need to use byte[] access for Java 9+ version jvms.

It all depends on the length of the String being inspected. If, as the question says, it is for long strings, the fastest way to inspect the string is to use reflection to access the backing char[] of the string.

A fully randomized benchmark with JDK 8 (win32 and win64) on an 64 AMD Phenom II 4 core 955 @ 3.2 GHZ (in both client mode and server mode) with 9 different techniques (see below!) shows that using String.charAt(n) is the fastest for small strings and that using reflection to access the String backing array is almost twice as fast for large strings.

THE EXPERIMENT

  • 9 different optimization techniques are tried.

  • All string contents are randomized

  • The test are done for string sizes in multiples of two starting with 0,1,2,4,8,16 etc.

  • The tests are done 1,000 times per string size

  • The tests are shuffled into random order each time. In other words, the tests are done in random order every time they are done, over 1000 times over.

  • The entire test suite is done forwards, and backwards, to show the effect of JVM warmup on optimization and times.

  • The entire suite is done twice, once in -client mode and the other in -server mode.

CONCLUSIONS

-client mode (32 bit)

For strings 1 to 256 characters in length, calling string.charAt(i) wins with an average processing of 13.4 million to 588 million characters per second.

Also, it is overall 5.5% faster (client) and 13.9% (server) like this:

    for (int i = 0; i < data.length(); i++) {
        if (data.charAt(i) <= ' ') {
            doThrow();
        }
    }

than like this with a local final length variable:

    final int len = data.length();
    for (int i = 0; i < len; i++) {
        if (data.charAt(i) <= ' ') {
            doThrow();
        }
    }

For long strings, 512 to 256K characters length, using reflection to access the String's backing array is fastest. This technique is almost twice as fast as String.charAt(i) (178% faster). The average speed over this range was 1.111 billion characters per second.

The Field must be obtained ahead of time and then it can be re-used in the library on different strings. Interestingly, unlike the code above, with Field access, it is 9% faster to have a local final length variable than to use 'chars.length' in the loop check. Here is how Field access can be setup as fastest:

   final Field field = String.class.getDeclaredField("value");
   field.setAccessible(true);

   try {
       final char[] chars = (char[]) field.get(data);
       final int len = chars.length;
       for (int i = 0; i < len; i++) {
           if (chars[i] <= ' ') {
               doThrow();
           }
       }
       return len;
   } catch (Exception ex) {
       throw new RuntimeException(ex);
   }

Special comments on -server mode

Field access starting winning after 32 character length strings in server mode on a 64 bit Java machine on my AMD 64 machine. That was not seen until 512 characters length in client mode.

Also worth noting I think, when I was running JDK 8 (32 bit build) in server mode, the overall performance was 7% slower for both large and small strings. This was with build 121 Dec 2013 of JDK 8 early release. So, for now, it seems that 32 bit server mode is slower than 32 bit client mode.

That being said ... it seems the only server mode that is worth invoking is on a 64 bit machine. Otherwise it actually hampers performance.

For 32 bit build running in -server mode on an AMD64, I can say this:

  1. String.charAt(i) is the clear winner overall. Although between sizes 8 to 512 characters there were winners among 'new' 'reuse' and 'field'.
  2. String.charAt(i) is 45% faster in client mode
  3. Field access is twice as fast for large Strings in client mode.

Also worth saying, String.chars() (Stream and the parallel version) are a bust. Way slower than any other way. The Streams API is a rather slow way to perform general string operations.

Wish List

Java String could have predicate accepting optimized methods such as contains(predicate), forEach(consumer), forEachWithIndex(consumer). Thus, without the need for the user to know the length or repeat calls to String methods, these could help parsing libraries beep-beep beep speedup.

Keep dreaming :)

Happy Strings!

~SH

The test used the following 9 methods of testing the string for the presence of whitespace:

"charAt1" -- CHECK THE STRING CONTENTS THE USUAL WAY:

int charAtMethod1(final String data) {
    final int len = data.length();
    for (int i = 0; i < len; i++) {
        if (data.charAt(i) <= ' ') {
            doThrow();
        }
    }
    return len;
}

"charAt2" -- SAME AS ABOVE BUT USE String.length() INSTEAD OF MAKING A FINAL LOCAL int FOR THE LENGTh

int charAtMethod2(final String data) {
    for (int i = 0; i < data.length(); i++) {
        if (data.charAt(i) <= ' ') {
            doThrow();
        }
    }
    return data.length();
}

"stream" -- USE THE NEW JAVA-8 String's IntStream AND PASS IT A PREDICATE TO DO THE CHECKING

int streamMethod(final String data, final IntPredicate predicate) {
    if (data.chars().anyMatch(predicate)) {
        doThrow();
    }
    return data.length();
}

"streamPara" -- SAME AS ABOVE, BUT OH-LA-LA - GO PARALLEL!!!

// avoid this at all costs
int streamParallelMethod(final String data, IntPredicate predicate) {
    if (data.chars().parallel().anyMatch(predicate)) {
        doThrow();
    }
    return data.length();
}

"reuse" -- REFILL A REUSABLE char[] WITH THE STRINGS CONTENTS

int reuseBuffMethod(final char[] reusable, final String data) {
    final int len = data.length();
    data.getChars(0, len, reusable, 0);
    for (int i = 0; i < len; i++) {
        if (reusable[i] <= ' ') {
            doThrow();
        }
    }
    return len;
}

"new1" -- OBTAIN A NEW COPY OF THE char[] FROM THE STRING

int newMethod1(final String data) {
    final int len = data.length();
    final char[] copy = data.toCharArray();
    for (int i = 0; i < len; i++) {
        if (copy[i] <= ' ') {
            doThrow();
        }
    }
    return len;
}

"new2" -- SAME AS ABOVE, BUT USE "FOR-EACH"

int newMethod2(final String data) {
    for (final char c : data.toCharArray()) {
        if (c <= ' ') {
            doThrow();
        }
    }
    return data.length();
}

"field1" -- FANCY!! OBTAIN FIELD FOR ACCESS TO THE STRING'S INTERNAL char[]

int fieldMethod1(final Field field, final String data) {
    try {
        final char[] chars = (char[]) field.get(data);
        final int len = chars.length;
        for (int i = 0; i < len; i++) {
            if (chars[i] <= ' ') {
                doThrow();
            }
        }
        return len;
    } catch (Exception ex) {
        throw new RuntimeException(ex);
    }
}

"field2" -- SAME AS ABOVE, BUT USE "FOR-EACH"

int fieldMethod2(final Field field, final String data) {
    final char[] chars;
    try {
        chars = (char[]) field.get(data);
    } catch (Exception ex) {
        throw new RuntimeException(ex);
    }
    for (final char c : chars) {
        if (c <= ' ') {
            doThrow();
        }
    }
    return chars.length;
}

COMPOSITE RESULTS FOR CLIENT -client MODE (forwards and backwards tests combined)

Note: that the -client mode with Java 32 bit and -server mode with Java 64 bit are the same as below on my AMD64 machine.

Size     WINNER  charAt1 charAt2  stream streamPar   reuse    new1    new2  field1  field2
1        charAt    77.0     72.0   462.0     584.0   127.5    89.5    86.0   159.5   165.0
2        charAt    38.0     36.5   284.0   32712.5    57.5    48.3    50.3    89.0    91.5
4        charAt    19.5     18.5   458.6    3169.0    33.0    26.8    27.5    54.1    52.6
8        charAt     9.8      9.9   100.5    1370.9    17.3    14.4    15.0    26.9    26.4
16       charAt     6.1      6.5    73.4     857.0     8.4     8.2     8.3    13.6    13.5
32       charAt     3.9      3.7    54.8     428.9     5.0     4.9     4.7     7.0     7.2
64       charAt     2.7      2.6    48.2     232.9     3.0     3.2     3.3     3.9     4.0
128      charAt     2.1      1.9    43.7     138.8     2.1     2.6     2.6     2.4     2.6
256      charAt     1.9      1.6    42.4      90.6     1.7     2.1     2.1     1.7     1.8
512      field1     1.7      1.4    40.6      60.5     1.4     1.9     1.9     1.3     1.4
1,024    field1     1.6      1.4    40.0      45.6     1.2     1.9     2.1     1.0     1.2
2,048    field1     1.6      1.3    40.0      36.2     1.2     1.8     1.7     0.9     1.1
4,096    field1     1.6      1.3    39.7      32.6     1.2     1.8     1.7     0.9     1.0
8,192    field1     1.6      1.3    39.6      30.5     1.2     1.8     1.7     0.9     1.0
16,384   field1     1.6      1.3    39.8      28.4     1.2     1.8     1.7     0.8     1.0
32,768   field1     1.6      1.3    40.0      26.7     1.3     1.8     1.7     0.8     1.0
65,536   field1     1.6      1.3    39.8      26.3     1.3     1.8     1.7     0.8     1.0
131,072  field1     1.6      1.3    40.1      25.4     1.4     1.9     1.8     0.8     1.0
262,144  field1     1.6      1.3    39.6      25.2     1.5     1.9     1.9     0.8     1.0

COMPOSITE RESULTS FOR SERVER -server MODE (forwards and backwards tests combined)

Note: this is the test for Java 32 bit running in server mode on an AMD64. The server mode for Java 64 bit was the same as Java 32 bit in client mode except that Field access starting winning after 32 characters size.

Size     WINNER  charAt1 charAt2  stream streamPar   reuse    new1    new2  field1  field2
1        charAt     74.5    95.5   524.5     783.0    90.5   102.5    90.5   135.0   151.5
2        charAt     48.5    53.0   305.0   30851.3    59.3    57.5    52.0    88.5    91.8
4        charAt     28.8    32.1   132.8    2465.1    37.6    33.9    32.3    49.0    47.0
8          new2     18.0    18.6    63.4    1541.3    18.5    17.9    17.6    25.4    25.8
16         new2     14.0    14.7   129.4    1034.7    12.5    16.2    12.0    16.0    16.6
32         new2      7.8     9.1    19.3     431.5     8.1     7.0     6.7     7.9     8.7
64        reuse      6.1     7.5    11.7     204.7     3.5     3.9     4.3     4.2     4.1
128       reuse      6.8     6.8     9.0     101.0     2.6     3.0     3.0     2.6     2.7
256      field2      6.2     6.5     6.9      57.2     2.4     2.7     2.9     2.3     2.3
512       reuse      4.3     4.9     5.8      28.2     2.0     2.6     2.6     2.1     2.1
1,024    charAt      2.0     1.8     5.3      17.6     2.1     2.5     3.5     2.0     2.0
2,048    charAt      1.9     1.7     5.2      11.9     2.2     3.0     2.6     2.0     2.0
4,096    charAt      1.9     1.7     5.1       8.7     2.1     2.6     2.6     1.9     1.9
8,192    charAt      1.9     1.7     5.1       7.6     2.2     2.5     2.6     1.9     1.9
16,384   charAt      1.9     1.7     5.1       6.9     2.2     2.5     2.5     1.9     1.9
32,768   charAt      1.9     1.7     5.1       6.1     2.2     2.5     2.5     1.9     1.9
65,536   charAt      1.9     1.7     5.1       5.5     2.2     2.4     2.4     1.9     1.9
131,072  charAt      1.9     1.7     5.1       5.4     2.3     2.5     2.5     1.9     1.9
262,144  charAt      1.9     1.7     5.1       5.1     2.3     2.5     2.5     1.9     1.9

FULL RUNNABLE PROGRAM CODE

(to test on Java 7 and earlier, remove the two streams tests)

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Random;
import java.util.function.IntPredicate;

/**
 * @author Saint Hill <http://stackoverflow.com/users/1584255/saint-hill>
 */
public final class TestStrings {

    // we will not test strings longer than 512KM
    final int MAX_STRING_SIZE = 1024 * 256;

    // for each string size, we will do all the tests
    // this many times
    final int TRIES_PER_STRING_SIZE = 1000;

    public static void main(String[] args) throws Exception {
        new TestStrings().run();
    }

    void run() throws Exception {

        // double the length of the data until it reaches MAX chars long
        // 0,1,2,4,8,16,32,64,128,256 ... 
        final List<Integer> sizes = new ArrayList<>();
        for (int n = 0; n <= MAX_STRING_SIZE; n = (n == 0 ? 1 : n * 2)) {
            sizes.add(n);
        }

        // CREATE RANDOM (FOR SHUFFLING ORDER OF TESTS)
        final Random random = new Random();

        System.out.println("Rate in nanoseconds per character inspected.");
        System.out.printf("==== FORWARDS (tries per size: %s) ==== \n", TRIES_PER_STRING_SIZE);

        printHeadings(TRIES_PER_STRING_SIZE, random);

        for (int size : sizes) {
            reportResults(size, test(size, TRIES_PER_STRING_SIZE, random));
        }

        // reverse order or string sizes
        Collections.reverse(sizes);

        System.out.println("");
        System.out.println("Rate in nanoseconds per character inspected.");
        System.out.printf("==== BACKWARDS (tries per size: %s) ==== \n", TRIES_PER_STRING_SIZE);

        printHeadings(TRIES_PER_STRING_SIZE, random);

        for (int size : sizes) {
            reportResults(size, test(size, TRIES_PER_STRING_SIZE, random));

        }
    }

    ///
    ///
    ///  METHODS OF CHECKING THE CONTENTS
    ///  OF A STRING. ALWAYS CHECKING FOR
    ///  WHITESPACE (CHAR <=' ')
    ///  
    ///
    // CHECK THE STRING CONTENTS
    int charAtMethod1(final String data) {
        final int len = data.length();
        for (int i = 0; i < len; i++) {
            if (data.charAt(i) <= ' ') {
                doThrow();
            }
        }
        return len;
    }

    // SAME AS ABOVE BUT USE String.length()
    // instead of making a new final local int 
    int charAtMethod2(final String data) {
        for (int i = 0; i < data.length(); i++) {
            if (data.charAt(i) <= ' ') {
                doThrow();
            }
        }
        return data.length();
    }

    // USE new Java-8 String's IntStream
    // pass it a PREDICATE to do the checking
    int streamMethod(final String data, final IntPredicate predicate) {
        if (data.chars().anyMatch(predicate)) {
            doThrow();
        }
        return data.length();
    }

    // OH LA LA - GO PARALLEL!!!
    int streamParallelMethod(final String data, IntPredicate predicate) {
        if (data.chars().parallel().anyMatch(predicate)) {
            doThrow();
        }
        return data.length();
    }

    // Re-fill a resuable char[] with the contents
    // of the String's char[]
    int reuseBuffMethod(final char[] reusable, final String data) {
        final int len = data.length();
        data.getChars(0, len, reusable, 0);
        for (int i = 0; i < len; i++) {
            if (reusable[i] <= ' ') {
                doThrow();
            }
        }
        return len;
    }

    // Obtain a new copy of char[] from String
    int newMethod1(final String data) {
        final int len = data.length();
        final char[] copy = data.toCharArray();
        for (int i = 0; i < len; i++) {
            if (copy[i] <= ' ') {
                doThrow();
            }
        }
        return len;
    }

    // Obtain a new copy of char[] from String
    // but use FOR-EACH
    int newMethod2(final String data) {
        for (final char c : data.toCharArray()) {
            if (c <= ' ') {
                doThrow();
            }
        }
        return data.length();
    }

    // FANCY!
    // OBTAIN FIELD FOR ACCESS TO THE STRING'S
    // INTERNAL CHAR[]
    int fieldMethod1(final Field field, final String data) {
        try {
            final char[] chars = (char[]) field.get(data);
            final int len = chars.length;
            for (int i = 0; i < len; i++) {
                if (chars[i] <= ' ') {
                    doThrow();
                }
            }
            return len;
        } catch (Exception ex) {
            throw new RuntimeException(ex);
        }
    }

    // same as above but use FOR-EACH
    int fieldMethod2(final Field field, final String data) {
        final char[] chars;
        try {
            chars = (char[]) field.get(data);
        } catch (Exception ex) {
            throw new RuntimeException(ex);
        }
        for (final char c : chars) {
            if (c <= ' ') {
                doThrow();
            }
        }
        return chars.length;
    }

    /**
     *
     * Make a list of tests. We will shuffle a copy of this list repeatedly
     * while we repeat this test.
     *
     * @param data
     * @return
     */
    List<Jobber> makeTests(String data) throws Exception {
        // make a list of tests
        final List<Jobber> tests = new ArrayList<Jobber>();

        tests.add(new Jobber("charAt1") {
            int check() {
                return charAtMethod1(data);
            }
        });

        tests.add(new Jobber("charAt2") {
            int check() {
                return charAtMethod2(data);
            }
        });

        tests.add(new Jobber("stream") {
            final IntPredicate predicate = new IntPredicate() {
                public boolean test(int value) {
                    return value <= ' ';
                }
            };

            int check() {
                return streamMethod(data, predicate);
            }
        });

        tests.add(new Jobber("streamPar") {
            final IntPredicate predicate = new IntPredicate() {
                public boolean test(int value) {
                    return value <= ' ';
                }
            };

            int check() {
                return streamParallelMethod(data, predicate);
            }
        });

        // Reusable char[] method
        tests.add(new Jobber("reuse") {
            final char[] cbuff = new char[MAX_STRING_SIZE];

            int check() {
                return reuseBuffMethod(cbuff, data);
            }
        });

        // New char[] from String
        tests.add(new Jobber("new1") {
            int check() {
                return newMethod1(data);
            }
        });

        // New char[] from String
        tests.add(new Jobber("new2") {
            int check() {
                return newMethod2(data);
            }
        });

        // Use reflection for field access
        tests.add(new Jobber("field1") {
            final Field field;

            {
                field = String.class.getDeclaredField("value");
                field.setAccessible(true);
            }

            int check() {
                return fieldMethod1(field, data);
            }
        });

        // Use reflection for field access
        tests.add(new Jobber("field2") {
            final Field field;

            {
                field = String.class.getDeclaredField("value");
                field.setAccessible(true);
            }

            int check() {
                return fieldMethod2(field, data);
            }
        });

        return tests;
    }

    /**
     * We use this class to keep track of test results
     */
    abstract class Jobber {

        final String name;
        long nanos;
        long chars;
        long runs;

        Jobber(String name) {
            this.name = name;
        }

        abstract int check();

        final double nanosPerChar() {
            double charsPerRun = chars / runs;
            long nanosPerRun = nanos / runs;
            return charsPerRun == 0 ? nanosPerRun : nanosPerRun / charsPerRun;
        }

        final void run() {
            runs++;
            long time = System.nanoTime();
            chars += check();
            nanos += System.nanoTime() - time;
        }
    }

    // MAKE A TEST STRING OF RANDOM CHARACTERS A-Z
    private String makeTestString(int testSize, char start, char end) {
        Random r = new Random();
        char[] data = new char[testSize];
        for (int i = 0; i < data.length; i++) {
            data[i] = (char) (start + r.nextInt(end));
        }
        return new String(data);
    }

    // WE DO THIS IF WE FIND AN ILLEGAL CHARACTER IN THE STRING
    public void doThrow() {
        throw new RuntimeException("Bzzzt -- Illegal Character!!");
    }

    /**
     * 1. get random string of correct length 2. get tests (List<Jobber>) 3.
     * perform tests repeatedly, shuffling each time
     */
    List<Jobber> test(int size, int tries, Random random) throws Exception {
        String data = makeTestString(size, 'A', 'Z');
        List<Jobber> tests = makeTests(data);
        List<Jobber> copy = new ArrayList<>(tests);
        while (tries-- > 0) {
            Collections.shuffle(copy, random);
            for (Jobber ti : copy) {
                ti.run();
            }
        }
        // check to make sure all char counts the same
        long runs = tests.get(0).runs;
        long count = tests.get(0).chars;
        for (Jobber ti : tests) {
            if (ti.runs != runs && ti.chars != count) {
                throw new Exception("Char counts should match if all correct algorithms");
            }
        }
        return tests;
    }

    private void printHeadings(final int TRIES_PER_STRING_SIZE, final Random random) throws Exception {
        System.out.print("  Size");
        for (Jobber ti : test(0, TRIES_PER_STRING_SIZE, random)) {
            System.out.printf("%9s", ti.name);
        }
        System.out.println("");
    }

    private void reportResults(int size, List<Jobber> tests) {
        System.out.printf("%6d", size);
        for (Jobber ti : tests) {
            System.out.printf("%,9.2f", ti.nanosPerChar());
        }
        System.out.println("");
    }
}

JSON to TypeScript class instance?

The best solution I found when dealing with Typescript classes and json objects: add a constructor in your Typescript class that takes the json data as parameter. In that constructor you extend your json object with jQuery, like this: $.extend( this, jsonData). $.extend allows keeping the javascript prototypes while adding the json object's properties.

export class Foo
{
    Name: string;
    getName(): string { return this.Name };

    constructor( jsonFoo: any )
    {
        $.extend( this, jsonFoo);
    }
}

In your ajax callback, translate your jsons in a your typescript object like this:

onNewFoo( jsonFoos : any[] )
{
  let receviedFoos = $.map( jsonFoos, (json) => { return new Foo( json ); } );

  // then call a method:
  let firstFooName = receviedFoos[0].GetName();
}

If you don't add the constructor, juste call in your ajax callback:

let newFoo = new Foo();
$.extend( newFoo, jsonData);
let name = newFoo.GetName()

...but the constructor will be useful if you want to convert the children json object too. See my detailed answer here.

pip installing in global site-packages instead of virtualenv

For Python 3ers

Try updating. I had this exact same problem and tried Chases' answer, however no success. The quickest way to refactor this is to update your Python Minor / Patch version if possible. I noticed that I was running 3.5.1 and updated to 3.5.2. Pyvenv once again works.

Date constructor returns NaN in IE, but works in Firefox and Chrome

I always store my date in UTC time.

This is my own function made from the different functions I found in this page.

It takes a STRING as a mysql DATETIME format (example : 2013-06-15 15:21:41). The checking with the regex is optional. You can delete this part to improve performance.

This function return a timestamp.

The DATETIME is considered as a UTC date. Be carefull : If you expect a local datetime, this function is not for you.

    function datetimeToTimestamp(datetime)
    {
        var regDatetime = /^[0-9]{4}-(?:[0]?[0-9]{1}|10|11|12)-(?:[012]?[0-9]{1}|30|31)(?: (?:[01]?[0-9]{1}|20|21|22|23)(?::[0-5]?[0-9]{1})?(?::[0-5]?[0-9]{1})?)?$/;
        if(regDatetime.test(datetime) === false)
            throw("Wrong format for the param. `Y-m-d H:i:s` expected.");

        var a=datetime.split(" ");
        var d=a[0].split("-");
        var t=a[1].split(":");

        var date = new Date();
        date.setUTCFullYear(d[0],(d[1]-1),d[2]);
        date.setUTCHours(t[0],t[1],t[2], 0);

        return date.getTime();
    }

Copy / Put text on the clipboard with FireFox, Safari and Chrome

There is now a way to easily do this in most modern browsers using

document.execCommand('copy');

This will copy currently selected text. You can select a textArea or input field using

document.getElementById('myText').select();

To invisibly copy text you can quickly generate a textArea, modify the text in the box, select it, copy it, and then delete the textArea. In most cases this textArea wont even flash onto the screen.

For security reasons, browsers will only allow you copy if a user takes some kind of action (ie. clicking a button). One way to do this would be to add an onClick event to a html button that calls a method which copies the text.

A full example:

_x000D_
_x000D_
function copier(){_x000D_
  document.getElementById('myText').select();_x000D_
  document.execCommand('copy');_x000D_
}
_x000D_
<button onclick="copier()">Copy</button>_x000D_
<textarea id="myText">Copy me PLEASE!!!</textarea>
_x000D_
_x000D_
_x000D_

Twitter Bootstrap alert message close and open again

Based on the other answers and changing data-dismiss to data-hide, this example handles opening the alert from a link and allows the alert to be opened and closed repeatedly

$('a.show_alert').click(function() {
    var $theAlert = $('.my_alert'); /* class on the alert */
    $theAlert.css('display','block');
   // set up the close event when the alert opens
   $theAlert.find('a[data-hide]').click(function() {
     $(this).parent().hide(); /* hide the alert */
   });
});

What is Inversion of Control?

Inversion of Control, (or IoC), is about getting freedom (You get married, you lost freedom and you are being controlled. You divorced, you have just implemented Inversion of Control. That's what we called, "decoupled". Good computer system discourages some very close relationship.) more flexibility (The kitchen in your office only serves clean tap water, that is your only choice when you want to drink. Your boss implemented Inversion of Control by setting up a new coffee machine. Now you get the flexibility of choosing either tap water or coffee.) and less dependency (Your partner has a job, you don't have a job, you financially depend on your partner, so you are controlled. You find a job, you have implemented Inversion of Control. Good computer system encourages in-dependency.)

When you use a desktop computer, you have slaved (or say, controlled). You have to sit before a screen and look at it. Using the keyboard to type and using the mouse to navigate. And a badly written software can slave you even more. If you replace your desktop with a laptop, then you somewhat inverted control. You can easily take it and move around. So now you can control where you are with your computer, instead of your computer controlling it.

By implementing Inversion of Control, a software/object consumer gets more controls/options over the software/objects, instead of being controlled or having fewer options.

With the above ideas in mind. We still miss a key part of IoC. In the scenario of IoC, the software/object consumer is a sophisticated framework. That means the code you created is not called by yourself. Now let's explain why this way works better for a web application.

Suppose your code is a group of workers. They need to build a car. These workers need a place and tools (a software framework) to build the car. A traditional software framework will be like a garage with many tools. So the workers need to make a plan themselves and use the tools to build the car. Building a car is not an easy business, it will be really hard for the workers to plan and cooperate properly. A modern software framework will be like a modern car factory with all the facilities and managers in place. The workers do not have to make any plan, the managers (part of the framework, they are the smartest people and made the most sophisticated plan) will help coordinate so that the workers know when to do their job (framework calls your code). The workers just need to be flexible enough to use any tools the managers give to them (by using Dependency Injection).

Although the workers give the control of managing the project on the top level to the managers (the framework). But it is good to have some professionals help out. This is the concept of IoC truly come from.

Modern Web applications with an MVC architecture depends on the framework to do URL Routing and put Controllers in place for the framework to call.

Dependency Injection and Inversion of Control are related. Dependency Injection is at the micro level and Inversion of Control is at the macro level. You have to eat every bite (implement DI) in order to finish a meal (implement IoC).