Programs & Examples On #Visual c++ 2005

The November 2005 release of Microsoft Visual C++, a C and C++ compiler for Windows, also known as the VC8 compiler.

URL string format for connecting to Oracle database with JDBC

DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());         
connection = DriverManager.getConnection("jdbc:oracle:thin:@machinename:portnum:schemaname","userid","password");

When should I use semicolons in SQL Server?

I still have a lot to learn about T-SQL, but in working up some code for a transaction (and basing code on examples from stackoverflow and other sites) I found a case where it seems a semicolon is required and if it is missing, the statement does not seem to execute at all and no error is raised. This doesn't seem to be covered in any of the above answers. (This was using MS SQL Server 2012.)

Once I had the transaction working the way I wanted, I decided to put a try-catch around it so if there are any errors it gets rolled back. Only after doing this, the transaction was not committed (SSMS confirms this when trying to close the window with a nice message alerting you to the fact that there is an uncommitted transaction.

So this

COMMIT TRANSACTION 

outside a BEGIN TRY/END TRY block worked fine to commit the transaction, but inside the block it had to be

COMMIT TRANSACTION;

Note there is no error or warning provided and no indication that the transaction is still uncommitted until attempting to close the query tab.

Fortunately this causes such a huge problem that it is immediately obvious that there is a problem. Unfortunately since no error (syntax or otherwise) is reported it was not immediately obvious what the problem was.

Contrary-wise, ROLLBACK TRANSACTION seems to work equally well in the BEGIN CATCH block with or without a semicolon.

There may be some logic to this but it feels arbitrary and Alice-in-Wonderland-ish.

How to copy a file along with directory structure/path using python?

To create all intermediate-level destination directories you could use os.makedirs() before copying:

import os
import shutil

srcfile = 'a/long/long/path/to/file.py'
dstroot = '/home/myhome/new_folder'


assert not os.path.isabs(srcfile)
dstdir =  os.path.join(dstroot, os.path.dirname(srcfile))

os.makedirs(dstdir) # create all directories, raise an error if it already exists
shutil.copy(srcfile, dstdir)

How do I convert a pandas Series or index to a Numpy array?

Since pandas v0.13 you can also use get_values:

df.index.get_values()

How to remove the last character from a string?

Why not just one liner?

public static String removeLastChar(String str) {
    return removeLastChars(str, 1);
}

public static String removeLastChars(String str, int chars) {
    return str.substring(0, str.length() - chars);
}

Full Code

public class Main {
    public static void main (String[] args) throws java.lang.Exception {
        String s1 = "Remove Last CharacterY";
        String s2 = "Remove Last Character2";
        System.out.println("After removing s1==" + removeLastChar(s1) + "==");
        System.out.println("After removing s2==" + removeLastChar(s2) + "==");
    }
    
    public static String removeLastChar(String str) {
        return removeLastChars(str, 1);
    }

    public static String removeLastChars(String str, int chars) {
        return str.substring(0, str.length() - chars);
    }
}

Demo

Removing duplicates from rows based on specific columns in an RDD/Spark DataFrame

The below programme will help you drop duplicates on whole , or if you want to drop duplicates based on certain columns , you can even do that:

import org.apache.spark.sql.SparkSession

object DropDuplicates {
def main(args: Array[String]) {
val spark =
  SparkSession.builder()
    .appName("DataFrame-DropDuplicates")
    .master("local[4]")
    .getOrCreate()

import spark.implicits._

// create an RDD of tuples with some data
val custs = Seq(
  (1, "Widget Co", 120000.00, 0.00, "AZ"),
  (2, "Acme Widgets", 410500.00, 500.00, "CA"),
  (3, "Widgetry", 410500.00, 200.00, "CA"),
  (4, "Widgets R Us", 410500.00, 0.0, "CA"),
  (3, "Widgetry", 410500.00, 200.00, "CA"),
  (5, "Ye Olde Widgete", 500.00, 0.0, "MA"),
  (6, "Widget Co", 12000.00, 10.00, "AZ")
)
val customerRows = spark.sparkContext.parallelize(custs, 4)

// convert RDD of tuples to DataFrame by supplying column names
val customerDF = customerRows.toDF("id", "name", "sales", "discount", "state")

println("*** Here's the whole DataFrame with duplicates")

customerDF.printSchema()

customerDF.show()

// drop fully identical rows
val withoutDuplicates = customerDF.dropDuplicates()

println("*** Now without duplicates")

withoutDuplicates.show()

// drop fully identical rows
val withoutPartials = customerDF.dropDuplicates(Seq("name", "state"))

println("*** Now without partial duplicates too")

withoutPartials.show()

 }
 }

How to use count and group by at the same select statement

This will do what you want (list of towns, with the number of users in each):

select town, count(town) 
from user
group by town

You can use most aggregate functions when using GROUP BY.

Update (following change to question and comments)

You can declare a variable for the number of users and set it to the number of users then select with that.

DECLARE @numOfUsers INT
SET @numOfUsers = SELECT COUNT(*) FROM user

SELECT DISTINCT town, @numOfUsers
FROM user

Change default text in input type="file"?

You can use this approach, it works even if a lot of files inputs.

_x000D_
_x000D_
const fileBlocks = document.querySelectorAll('.file-block')_x000D_
const buttons = document.querySelectorAll('.btn-select-file')_x000D_
_x000D_
;[...buttons].forEach(function (btn) {_x000D_
  btn.onclick = function () {_x000D_
    btn.parentElement.querySelector('input[type="file"]').click()_x000D_
  }_x000D_
})_x000D_
_x000D_
;[...fileBlocks].forEach(function (block) {_x000D_
  block.querySelector('input[type="file"]').onchange = function () {_x000D_
    const filename = this.files[0].name_x000D_
_x000D_
    block.querySelector('.btn-select-file').textContent = 'File selected: ' + filename_x000D_
  }_x000D_
})
_x000D_
.btn-select-file {_x000D_
  border-radius: 20px;_x000D_
}_x000D_
_x000D_
input[type="file"] {_x000D_
  display: none;_x000D_
}
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
<div class="file-block">_x000D_
  <button class="btn-select-file">Select Image 1</button>_x000D_
  <input type="file">_x000D_
</div>_x000D_
<br>_x000D_
<div class="file-block">_x000D_
  <button class="btn-select-file">Select Image 2</button>_x000D_
  <input type="file">_x000D_
</div>
_x000D_
_x000D_
_x000D_

Subscript out of range error in this Excel VBA script

Private Sub CommandButton1_Click()

    Dim Data As Object, Employee As Object

    Application.ScreenUpdating = False

    Set Data = ThisWorkbook.Sheets("Data")

    Set Employee = ThisWorkbook.Sheets("Employee Names")

    Data.Range("AK1").Value = "Lookup"

    Data.Range("AK2:AK" & Data.Range("A1").End(xlDown).Row).Formula = "=VLOOKUP(E2,'Employee Names'!$A:$A,1,0)"

    Data.Range("AK2:AK" & Data.Range("A1").End(xlDown).Row).Value = Data.Range("AK2:AK" & Data.Range("A1").End(xlDown).Row).Value

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).AutoFilter Field:=5, Criteria1:="<>"

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).AutoFilter Field:=37, Criteria1:="#N/A"

    Application.DisplayAlerts = False

    Data.AutoFilter.Range.Offset(1, 0).Rows.SpecialCells(xlCellTypeVisible).Delete (xlShiftUp)

    Data.Range("AK:AK").Delete

    Data.AutoFilterMode = False

    'Selection.AutoFilter

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).AutoFilter Field:=7, Criteria1:="="

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).AutoFilter Field:=12, Criteria1:="<>"

    Worksheets("Data").Range("A1:AK" & Data.Range("A1").End(xlDown).Row).Copy

    Sheets.Add(After:=Sheets(Sheets.Count)).Name = "DrfeeRequested"

    Set Dr = ThisWorkbook.Worksheets("DrfeeRequested")

    Dr.Range("A1").PasteSpecial Paste:=xlPasteValues

    Application.CutCopyMode = False

    Data.AutoFilterMode = False

    'DrfeeRequested.AutoFilterMode = False

    Selection.AutoFilter

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).AutoFilter Field:=13, Criteria1:="<>"

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).Copy

    Sheets.Add(After:=Sheets(Sheets.Count)).Name = "RateLockfollowup"
    Set Ratefolup = ThisWorkbook.Worksheets("RateLockfollowup")

    Ratefolup.Range("A1").PasteSpecial Paste:=xlPasteValues

    Application.CutCopyMode = False

    Data.AutoFilterMode = False

    Selection.AutoFilter

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).AutoFilter Field:=19, Criteria1:="="

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).AutoFilter Field:=13, Criteria1:="<>"

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).Copy

    Sheets.Add(After:=Sheets(Sheets.Count)).Name = "Lockedlefollowup"
    Set Lockfolup = ThisWorkbook.Worksheets("Lockedlefollowup")

    Lockfolup.Range("A1").PasteSpecial Paste:=xlPasteValues

    Application.CutCopyMode = False

    Data.AutoFilterMode = False

    Selection.AutoFilter

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).AutoFilter Field:=19, Criteria1:="="

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).Copy

    Sheets.Add(After:=Sheets(Sheets.Count)).Name = "Hoifollowup"

    Set Hoifolup = ThisWorkbook.Worksheets("Hoifollowup")

    Hoifolup.Range("A1").PasteSpecial Paste:=xlPasteValues

    Application.CutCopyMode = False

    Data.AutoFilterMode = False

    Selection.AutoFilter

    TodayDT = Format(Now())

    Weekdy = Weekday(Now())

    If Weekdy = 2 Then
       LastTwoDays = Now() - Weekday(Now(), 3)
    ElseIf Weekdy = 3 Then
       LastTwoDays = Now() - Weekday(Now(), 3)
    ElseIf Weekdy = 4 Then
       LastTwoDays = Now() - Weekday(Now(), 3)
    ElseIf Weekdy = 5 Then
       LastTwoDays = Now() - Weekday(Now(), 3)
    ElseIf Weekdy = 6 Then
       LastTwoDays = Now() - Weekday(Now(), 3)
    Else
       MsgBox "Today Satuarday OR Sunday Data is not Available"
    End If

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).AutoFilter Field:=12, Criteria1:="="

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).AutoFilter Field:=11, Criteria1:="<>"

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).AutoFilter Field:=11, Criteria1:=" TodayDT", Operator:=xlAnd, Criteria2:="LastTwoDays"

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).Copy

    Sheets.Add(After:=Sheets(Sheets.Count)).Name = "DRfeefollowup"

    Set Drfreefolup = ThisWorkbook.Worksheets("DRfeefollowup")

    Drfreefolup.Range("A1").PasteSpecial Paste:=xlPasteValues

    Application.CutCopyMode = False

    Data.AutoFilterMode = False

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).AutoFilter Field:=15, Criteria1:="yes"

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).AutoFilter Field:=19, Criteria1:="x"

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).AutoFilter Field:=12, Criteria1:="<>"

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).AutoFilter Field:=13, Criteria1:="<>"

    'Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).AutoFilter Field:=14, criterial:="<>"

    Data.Range("A1:AK" & Data.Range("A1").End(xlDown).Row).Copy

    Sheets.Add(After:=Sheets(Sheets.Count)).Name = "Drworkblefiles"

    Set Drworkblefiles = ThisWorkbook.Worksheets("Drworkblefiles")

    Drworkblefiles.Range("A1").PasteSpecial Paste:=xlPasteValues

    Application.CutCopyMode = False

    Data.Range("A1").AutoFilter

   End Sub

 Private Sub CommandButton2_Click()


    Sheets("Data").Range("A1:AJ" & Sheets("Data").Range("A1").End(xlDown).Row).Clear

    MsgBox "Please paste new data in data sheet"


End Sub

Is there a RegExp.escape function in JavaScript?

The function linked above is insufficient. It fails to escape ^ or $ (start and end of string), or -, which in a character group is used for ranges.

Use this function:

function escapeRegex(string) {
    return string.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&');
}

While it may seem unnecessary at first glance, escaping - (as well as ^) makes the function suitable for escaping characters to be inserted into a character class as well as the body of the regex.

Escaping / makes the function suitable for escaping characters to be used in a JavaScript regex literal for later evaluation.

As there is no downside to escaping either of them, it makes sense to escape to cover wider use cases.

And yes, it is a disappointing failing that this is not part of standard JavaScript.

Multiple Inheritance in C#

You could have one abstract base class that implements both IFirst and ISecond, and then inherit from just that base.

How to set layout_weight attribute dynamically from code?

If layoutparams is already defined (in XML or dynamically), Here's a one liner:

((LinearLayout.LayoutParams) mView.getLayoutParams()).weight = 1;

Linking to an external URL in Javadoc?

This creates a "See Also" heading containing the link, i.e.:

/**
 * @see <a href="http://google.com">http://google.com</a>
 */

will render as:

See Also:
           http://google.com

whereas this:

/**
 * See <a href="http://google.com">http://google.com</a>
 */

will create an in-line link:

See http://google.com

How can I link to a specific glibc version?

Setup 1: compile your own glibc without dedicated GCC and use it

Since it seems impossible to do just with symbol versioning hacks, let's go one step further and compile glibc ourselves.

This setup might work and is quick as it does not recompile the whole GCC toolchain, just glibc.

But it is not reliable as it uses host C runtime objects such as crt1.o, crti.o, and crtn.o provided by glibc. This is mentioned at: https://sourceware.org/glibc/wiki/Testing/Builds?action=recall&rev=21#Compile_against_glibc_in_an_installed_location Those objects do early setup that glibc relies on, so I wouldn't be surprised if things crashed in wonderful and awesomely subtle ways.

For a more reliable setup, see Setup 2 below.

Build glibc and install locally:

export glibc_install="$(pwd)/glibc/build/install"

git clone git://sourceware.org/git/glibc.git
cd glibc
git checkout glibc-2.28
mkdir build
cd build
../configure --prefix "$glibc_install"
make -j `nproc`
make install -j `nproc`

Setup 1: verify the build

test_glibc.c

#define _GNU_SOURCE
#include <assert.h>
#include <gnu/libc-version.h>
#include <stdatomic.h>
#include <stdio.h>
#include <threads.h>

atomic_int acnt;
int cnt;

int f(void* thr_data) {
    for(int n = 0; n < 1000; ++n) {
        ++cnt;
        ++acnt;
    }
    return 0;
}

int main(int argc, char **argv) {
    /* Basic library version check. */
    printf("gnu_get_libc_version() = %s\n", gnu_get_libc_version());

    /* Exercise thrd_create from -pthread,
     * which is not present in glibc 2.27 in Ubuntu 18.04.
     * https://stackoverflow.com/questions/56810/how-do-i-start-threads-in-plain-c/52453291#52453291 */
    thrd_t thr[10];
    for(int n = 0; n < 10; ++n)
        thrd_create(&thr[n], f, NULL);
    for(int n = 0; n < 10; ++n)
        thrd_join(thr[n], NULL);
    printf("The atomic counter is %u\n", acnt);
    printf("The non-atomic counter is %u\n", cnt);
}

Compile and run with test_glibc.sh:

#!/usr/bin/env bash
set -eux
gcc \
  -L "${glibc_install}/lib" \
  -I "${glibc_install}/include" \
  -Wl,--rpath="${glibc_install}/lib" \
  -Wl,--dynamic-linker="${glibc_install}/lib/ld-linux-x86-64.so.2" \
  -std=c11 \
  -o test_glibc.out \
  -v \
  test_glibc.c \
  -pthread \
;
ldd ./test_glibc.out
./test_glibc.out

The program outputs the expected:

gnu_get_libc_version() = 2.28
The atomic counter is 10000
The non-atomic counter is 8674

Command adapted from https://sourceware.org/glibc/wiki/Testing/Builds?action=recall&rev=21#Compile_against_glibc_in_an_installed_location but --sysroot made it fail with:

cannot find /home/ciro/glibc/build/install/lib/libc.so.6 inside /home/ciro/glibc/build/install

so I removed it.

ldd output confirms that the ldd and libraries that we've just built are actually being used as expected:

+ ldd test_glibc.out
        linux-vdso.so.1 (0x00007ffe4bfd3000)
        libpthread.so.0 => /home/ciro/glibc/build/install/lib/libpthread.so.0 (0x00007fc12ed92000)
        libc.so.6 => /home/ciro/glibc/build/install/lib/libc.so.6 (0x00007fc12e9dc000)
        /home/ciro/glibc/build/install/lib/ld-linux-x86-64.so.2 => /lib64/ld-linux-x86-64.so.2 (0x00007fc12f1b3000)

The gcc compilation debug output shows that my host runtime objects were used, which is bad as mentioned previously, but I don't know how to work around it, e.g. it contains:

COLLECT_GCC_OPTIONS=/usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crt1.o

Setup 1: modify glibc

Now let's modify glibc with:

diff --git a/nptl/thrd_create.c b/nptl/thrd_create.c
index 113ba0d93e..b00f088abb 100644
--- a/nptl/thrd_create.c
+++ b/nptl/thrd_create.c
@@ -16,11 +16,14 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */

+#include <stdio.h>
+
 #include "thrd_priv.h"

 int
 thrd_create (thrd_t *thr, thrd_start_t func, void *arg)
 {
+  puts("hacked");
   _Static_assert (sizeof (thr) == sizeof (pthread_t),
                   "sizeof (thr) != sizeof (pthread_t)");

Then recompile and re-install glibc, and recompile and re-run our program:

cd glibc/build
make -j `nproc`
make -j `nproc` install
./test_glibc.sh

and we see hacked printed a few times as expected.

This further confirms that we actually used the glibc that we compiled and not the host one.

Tested on Ubuntu 18.04.

Setup 2: crosstool-NG pristine setup

This is an alternative to setup 1, and it is the most correct setup I've achieved far: everything is correct as far as I can observe, including the C runtime objects such as crt1.o, crti.o, and crtn.o.

In this setup, we will compile a full dedicated GCC toolchain that uses the glibc that we want.

The only downside to this method is that the build will take longer. But I wouldn't risk a production setup with anything less.

crosstool-NG is a set of scripts that downloads and compiles everything from source for us, including GCC, glibc and binutils.

Yes the GCC build system is so bad that we need a separate project for that.

This setup is only not perfect because crosstool-NG does not support building the executables without extra -Wl flags, which feels weird since we've built GCC itself. But everything seems to work, so this is only an inconvenience.

Get crosstool-NG and configure it:

git clone https://github.com/crosstool-ng/crosstool-ng
cd crosstool-ng
git checkout a6580b8e8b55345a5a342b5bd96e42c83e640ac5
export CT_PREFIX="$(pwd)/.build/install"
export PATH="/usr/lib/ccache:${PATH}"
./bootstrap
./configure --enable-local
make -j `nproc`
./ct-ng x86_64-unknown-linux-gnu
./ct-ng menuconfig

The only mandatory option that I can see, is making it match your host kernel version to use the correct kernel headers. Find your host kernel version with:

uname -a

which shows me:

4.15.0-34-generic

so in menuconfig I do:

  • Operating System
    • Version of linux

so I select:

4.14.71

which is the first equal or older version. It has to be older since the kernel is backwards compatible.

Now you can build with:

env -u LD_LIBRARY_PATH time ./ct-ng build CT_JOBS=`nproc`

and now wait for about thirty minutes to two hours for compilation.

Setup 2: optional configurations

The .config that we generated with ./ct-ng x86_64-unknown-linux-gnu has:

CT_GLIBC_V_2_27=y

To change that, in menuconfig do:

  • C-library
  • Version of glibc

save the .config, and continue with the build.

Or, if you want to use your own glibc source, e.g. to use glibc from the latest git, proceed like this:

  • Paths and misc options
    • Try features marked as EXPERIMENTAL: set to true
  • C-library
    • Source of glibc
      • Custom location: say yes
      • Custom location
        • Custom source location: point to a directory containing your glibc source

where glibc was cloned as:

git clone git://sourceware.org/git/glibc.git
cd glibc
git checkout glibc-2.28

Setup 2: test it out

Once you have built he toolchain that you want, test it out with:

#!/usr/bin/env bash
set -eux
install_dir="${CT_PREFIX}/x86_64-unknown-linux-gnu"
PATH="${PATH}:${install_dir}/bin" \
  x86_64-unknown-linux-gnu-gcc \
  -Wl,--dynamic-linker="${install_dir}/x86_64-unknown-linux-gnu/sysroot/lib/ld-linux-x86-64.so.2" \
  -Wl,--rpath="${install_dir}/x86_64-unknown-linux-gnu/sysroot/lib" \
  -v \
  -o test_glibc.out \
  test_glibc.c \
  -pthread \
;
ldd test_glibc.out
./test_glibc.out

Everything seems to work as in Setup 1, except that now the correct runtime objects were used:

COLLECT_GCC_OPTIONS=/home/ciro/crosstool-ng/.build/install/x86_64-unknown-linux-gnu/bin/../x86_64-unknown-linux-gnu/sysroot/usr/lib/../lib64/crt1.o

Setup 2: failed efficient glibc recompilation attempt

It does not seem possible with crosstool-NG, as explained below.

If you just re-build;

env -u LD_LIBRARY_PATH time ./ct-ng build CT_JOBS=`nproc`

then your changes to the custom glibc source location are taken into account, but it builds everything from scratch, making it unusable for iterative development.

If we do:

./ct-ng list-steps

it gives a nice overview of the build steps:

Available build steps, in order:
  - companion_tools_for_build
  - companion_libs_for_build
  - binutils_for_build
  - companion_tools_for_host
  - companion_libs_for_host
  - binutils_for_host
  - cc_core_pass_1
  - kernel_headers
  - libc_start_files
  - cc_core_pass_2
  - libc
  - cc_for_build
  - cc_for_host
  - libc_post_cc
  - companion_libs_for_target
  - binutils_for_target
  - debug
  - test_suite
  - finish
Use "<step>" as action to execute only that step.
Use "+<step>" as action to execute up to that step.
Use "<step>+" as action to execute from that step onward.

therefore, we see that there are glibc steps intertwined with several GCC steps, most notably libc_start_files comes before cc_core_pass_2, which is likely the most expensive step together with cc_core_pass_1.

In order to build just one step, you must first set the "Save intermediate steps" in .config option for the intial build:

  • Paths and misc options
    • Debug crosstool-NG
      • Save intermediate steps

and then you can try:

env -u LD_LIBRARY_PATH time ./ct-ng libc+ -j`nproc`

but unfortunately, the + required as mentioned at: https://github.com/crosstool-ng/crosstool-ng/issues/1033#issuecomment-424877536

Note however that restarting at an intermediate step resets the installation directory to the state it had during that step. I.e., you will have a rebuilt libc - but no final compiler built with this libc (and hence, no compiler libraries like libstdc++ either).

and basically still makes the rebuild too slow to be feasible for development, and I don't see how to overcome this without patching crosstool-NG.

Furthermore, starting from the libc step didn't seem to copy over the source again from Custom source location, further making this method unusable.

Bonus: stdlibc++

A bonus if you're also interested in the C++ standard library: How to edit and re-build the GCC libstdc++ C++ standard library source?

Convert 24 Hour time to 12 Hour plus AM/PM indication Oracle SQL

For the 24-hour time, you need to use HH24 instead of HH.

For the 12-hour time, the AM/PM indicator is written as A.M. (if you want periods in the result) or AM (if you don't). For example:

SELECT invoice_date,
       TO_CHAR(invoice_date, 'DD-MM-YYYY HH24:MI:SS') "Date 24Hr",
       TO_CHAR(invoice_date, 'DD-MM-YYYY HH:MI:SS AM') "Date 12Hr"
  FROM invoices
;

For more information on the format models you can use with TO_CHAR on a date, see http://docs.oracle.com/cd/E16655_01/server.121/e17750/ch4datetime.htm#NLSPG004.

Adjusting and image Size to fit a div (bootstrap)

I used this and works for me.

<div class="col-sm-3">
  <img src="xxx.png" style="width: auto; height: 195px;">
</div>

Eliminating duplicate values based on only one column of the table

I solve such queries using this pattern:

SELECT *
FROM t
WHERE t.field=(
  SELECT MAX(t.field) 
  FROM t AS t0 
  WHERE t.group_column1=t0.group_column1
    AND t.group_column2=t0.group_column2 ...)

That is it will select records where the value of a field is at its max value. To apply it to your query I used the common table expression so that I don't have to repeat the JOIN twice:

WITH site_history AS (
  SELECT sites.siteName, sites.siteIP, history.date
  FROM sites
  JOIN history USING (siteName)
)
SELECT *
FROM site_history h
WHERE date=(
  SELECT MAX(date) 
  FROM site_history h0 
  WHERE h.siteName=h0.siteName)
ORDER BY siteName

It's important to note that it works only if the field we're calculating the maximum for is unique. In your example the date field should be unique for each siteName, that is if the IP can't be changed multiple times per millisecond. In my experience this is commonly the case otherwise you don't know which record is the newest anyway. If the history table has an unique index for (site, date), this query is also very fast, index range scan on the history table scanning just the first item can be used.

Differences between Emacs and Vim

In your question, you haven't mentioned that you want it to program in Lisp! But as you have been commenting your answers, I have understood that you actually want a LISP programming interface.

For that precise task, simply forget about Vi. Emacs integration with LISP is wonderful! You should use SLIME. You will then have wonderful integration with the REPL, being able to eval functions, buffers or files directly into a running interpreter in an emacs buffer and much more...

Resize HTML5 canvas to fit window

I believe I have found an elegant solution to this:

JavaScript

/* important! for alignment, you should make things
 * relative to the canvas' current width/height.
 */
function draw() {
  var ctx = (a canvas context);
  ctx.canvas.width  = window.innerWidth;
  ctx.canvas.height = window.innerHeight;
  //...drawing code...
}

CSS

html, body {
  width:  100%;
  height: 100%;
  margin: 0;
}

Hasn't had any large negative performance impact for me, so far.

Adding a caption to an equation in LaTeX

As in this forum post by Gonzalo Medina, a third way may be:

\documentclass{article}
\usepackage{caption}

\DeclareCaptionType{equ}[][]
%\captionsetup[equ]{labelformat=empty}

\begin{document}

Some text

\begin{equ}[!ht]
  \begin{equation}
    a=b+c
  \end{equation}
\caption{Caption of the equation}
\end{equ}

Some other text
 
\end{document}

More details of the commands used from package caption: here.

A screenshot of the output of the above code:

screenshot of output

Struct like objects in Java

You can make a simple class with public fields and no methods in Java, but it is still a class and is still handled syntactically and in terms of memory allocation just like a class. There is no way to genuinely reproduce structs in Java.

Kotlin Android start new Activity

You can use both Kotlin and Java files in your application.

To switch between the two files, make sure you give them unique < action android:name="" in AndroidManifest.xml, like so:

            <activity android:name=".MainActivityKotlin">
                <intent-filter>
                    <action android:name="com.genechuang.basicfirebaseproject.KotlinActivity"/>
                    <category android:name="android.intent.category.DEFAULT" />
                    <action android:name="android.intent.action.MAIN" />
                    <category android:name="android.intent.category.LAUNCHER" />
                </intent-filter>
            </activity>
            <activity
                android:name="com.genechuang.basicfirebaseproject.MainActivityJava"
                android:label="MainActivityJava" >
                <intent-filter>
                    <action android:name="com.genechuang.basicfirebaseproject.JavaActivity" />
                    <category android:name="android.intent.category.DEFAULT" />
                </intent-filter>
            </activity>

Then in your MainActivity.kt (Kotlin file), to start an Activity written in Java, do this:

       val intent = Intent("com.genechuang.basicfirebaseproject.JavaActivity")
        startActivity(intent)

In your MainActivityJava.java (Java file), to start an Activity written in Kotlin, do this:

       Intent mIntent = new Intent("com.genechuang.basicfirebaseproject.KotlinActivity");
        startActivity(mIntent);

How can I remove a key from a Python dictionary?

Specifically to answer "is there a one line way of doing this?"

if 'key' in my_dict: del my_dict['key']

...well, you asked ;-)

You should consider, though, that this way of deleting an object from a dict is not atomic—it is possible that 'key' may be in my_dict during the if statement, but may be deleted before del is executed, in which case del will fail with a KeyError. Given this, it would be safest to either use dict.pop or something along the lines of

try:
    del my_dict['key']
except KeyError:
    pass

which, of course, is definitely not a one-liner.

SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data

May be its irrelevant answer but its working in my case...don't know what was wrong on my server...I just enable error log on Ubuntu 16.04 server.

//For PHP
error_reporting(E_ALL);
ini_set('display_errors', 1);

Convert byte slice to io.Reader

r := strings(byteData)

This also works to turn []byte into io.Reader

What is the difference between List and ArrayList?

There's no difference between list implementations in both of your examples. There's however a difference in a way you can further use variable myList in your code.

When you define your list as:

List myList = new ArrayList();

you can only call methods and reference members that are defined in the List interface. If you define it as:

ArrayList myList = new ArrayList();

you'll be able to invoke ArrayList-specific methods and use ArrayList-specific members in addition to those whose definitions are inherited from List.

Nevertheless, when you call a method of a List interface in the first example, which was implemented in ArrayList, the method from ArrayList will be called (because the List interface doesn't implement any methods).

That's called polymorphism. You can read up on it.

Lodash remove duplicates from array

Simply use _.uniqBy(). It creates duplicate-free version of an array.

This is a new way and available from 4.0.0 version.

_.uniqBy(data, 'id');

or

_.uniqBy(data, obj => obj.id);

Redirect all output to file in Bash

Use this - "require command here" > log_file_name 2>&1

Detail description of redirection operator in Unix/Linux.

The > operator redirects the output usually to a file but it can be to a device. You can also use >> to append.

If you don't specify a number then the standard output stream is assumed but you can also redirect errors

> file redirects stdout to file
1> file redirects stdout to file
2> file redirects stderr to file
&> file redirects stdout and stderr to file

/dev/null is the null device it takes any input you want and throws it away. It can be used to suppress any output.

PHP mail not working for some reason

Check your SMTP settings in your php.ini file. Your host should have some documentation about what credentials to use. Perhaps you can check your error log file, it might have more information available.

C# - Winforms - Global Variables

The consensus here is to put the global variables in a static class as static members. When you create a new Windows Forms application, it usually comes with a Program class (Program.cs), which is a static class and serves as the main entry point of the application. It lives for the the whole lifetime of the app, so I think it is best to put the global variables there instead of creating a new one.

static class Program
{
    public static string globalString = "This is a global string.";

    /// <summary>
    /// The main entry point for the application.
    /// </summary>
    [STAThread]
    static void Main()
    {
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
        Application.Run(new Form1());
    }
}

And use it as such:

public partial class Form1 : Form
{
    public Form1()
    {
        Program.globalString = "Accessible in Form1.";

        InitializeComponent();
    }
}

Making the main scrollbar always visible

I was able to get this to work by adding it to the body tag. Was nicer for me because I don't have anything on the html element.

body {
    overflow-y: scroll;
}

tsql returning a table from a function or store procedure

You don't need (shouldn't use) a function as far as I can tell. The stored procedure will return tabular data from any SELECT statements you include that return tabular data.

A stored proc does not use RETURN statements.

 CREATE PROCEDURE name
 AS

 SELECT stuff INTO #temptbl1

 .......


 SELECT columns FROM #temptbln

Installing Apache Maven Plugin for Eclipse

I found Maven Integration for Eclipse here.

http://download.eclipse.org/technology/m2e/releases

After installing restart eclipse. Worked for me running Eclipse Juno.

How to use a class from one C# project with another C# project

The first step is to make P2 reference P1 by doing the following

  • Right Click on the project and select "Add Reference"
  • Go to the Projects Tab
  • Select P1 and hit OK

Next you'll need to make sure that the classes in P1 are accessible to P2. The easiest way is to make them public.

public class MyType { ... }

Now you should be able to use them in P2 via their fully qualified name. Assuming the namespace of P1 is Project1 then the following would work

Project1.MyType obj = new Project1.MyType();

The preferred way though is to add a using for Project1 so you can use the types without qualification

using Project1;
...

public void Example() {
  MyType obj = new MyType();
}

How do I count the number of occurrences of a char in a String?

String s = "a.b.c.d";
int charCount = s.length() - s.replaceAll("\\.", "").length();

ReplaceAll(".") would replace all characters.

PhiLho's solution uses ReplaceAll("[^.]",""), which does not need to be escaped, since [.] represents the character 'dot', not 'any character'.

jquery smooth scroll to an anchor?

Try this one. It is a code from CSS tricks that I modified, it is pretty straight forward and does both horizontal and vertial scrolling. Needs JQuery. Here is a demo

$(function() {
  $('a[href*=#]:not([href=#])').click(function() {
    if (location.pathname.replace(/^\//,'') == this.pathname.replace(/^\//,'') && location.hostname == this.hostname) {
      var target = $(this.hash);
      target = target.length ? target : $('[name=' + this.hash.slice(1) +']');
      if (target.length) {
        $('html,body').animate({
          scrollTop: target.offset().top-10, scrollLeft:target.offset().left-10
        }, 1000);
        return false;
      }
    }
  });
});

Why use argparse rather than optparse?

Why should I use it instead of optparse? Are their new features I should know about?

@Nicholas's answer covers this well, I think, but not the more "meta" question you start with:

Why has yet another command-line parsing module been created?

That's the dilemma number one when any useful module is added to the standard library: what do you do when a substantially better, but backwards-incompatible, way to provide the same kind of functionality emerges?

Either you stick with the old and admittedly surpassed way (typically when we're talking about complicated packages: asyncore vs twisted, tkinter vs wx or Qt, ...) or you end up with multiple incompatible ways to do the same thing (XML parsers, IMHO, are an even better example of this than command-line parsers -- but the email package vs the myriad old ways to deal with similar issues isn't too far away either;-).

You may make threatening grumbles in the docs about the old ways being "deprecated", but (as long as you need to keep backwards compatibility) you can't really take them away without stopping large, important applications from moving to newer Python releases.

(Dilemma number two, not directly related to your question, is summarized in the old saying "the standard library is where good packages go to die"... with releases every year and a half or so, packages that aren't very, very stable, not needing releases any more often than that, can actually suffer substantially by being "frozen" in the standard library... but, that's really a different issue).

Wrapping a react-router Link in an html button

With styled components this can be easily achieved

First Design a styled button

import styled from "styled-components";
import {Link} from "react-router-dom";

const Button = styled.button`
  background: white;
  color:red;
  font-size: 1em;
  margin: 1em;
  padding: 0.25em 1em;
  border: 2px solid red;
  border-radius: 3px;
`
render(
    <Button as={Link} to="/home"> Text Goes Here </Button>
);

check styled component's home for more

Select a random sample of results from a query result

Sample function is used for sample data in ORACLE. So you can try like this:-

SELECT * FROM TABLE_NAME SAMPLE(50);

Here 50 is the percentage of data contained by the table. So if you want 1000 rows from 100000. You can execute a query like:

SELECT * FROM TABLE_NAME SAMPLE(1);

Hope this can help you.

Angular 6: How to set response type as text while making http call

On your backEnd, you should add:

@RequestMapping(value="/blabla",  produces="text/plain" , method = RequestMethod.GET)

On the frontEnd (Service):

methodBlabla() 
{
  const headers = new HttpHeaders().set('Content-Type', 'text/plain; charset=utf-8');
  return this.http.get(this.url,{ headers, responseType: 'text'});
}

"You tried to execute a query that does not include the specified aggregate function"

GROUP BY can be selected from Total row in query design view in MS Access.
If Total row not shown in design view (as in my case). You can go to SQL View and add GROUP By fname etc. Then Total row will automatically show in design view.
You have to select as Expression in this row for calculated fields.

MySQL parameterized queries

You have a few options available. You'll want to get comfortable with python's string iterpolation. Which is a term you might have more success searching for in the future when you want to know stuff like this.

Better for queries:

some_dictionary_with_the_data = {
    'name': 'awesome song',
    'artist': 'some band',
    etc...
}
cursor.execute ("""
            INSERT INTO Songs (SongName, SongArtist, SongAlbum, SongGenre, SongLength, SongLocation)
            VALUES
                (%(name)s, %(artist)s, %(album)s, %(genre)s, %(length)s, %(location)s)

        """, some_dictionary_with_the_data)

Considering you probably have all of your data in an object or dictionary already, the second format will suit you better. Also it sucks to have to count "%s" appearances in a string when you have to come back and update this method in a year :)

How do I check if file exists in jQuery or pure JavaScript?

This is an adaptation to the accepted answer, but I couldn't get what I needed from the answer, and had to test this worked as it was a hunch, so i'm putting my solution up here.

We needed to verify a local file existed, and only allow the file (a PDF) to open if it existed. If you omit the URL of the website, the browser will automatically determine the host name - making it work in localhost and on the server:

$.ajax({

    url: 'YourFolderOnWebsite/' + SomeDynamicVariable + '.pdf',
    type: 'HEAD',
    error: function () {
        //file not exists
        alert('PDF does not exist');

    },
    success: function () {
        //file exists
        window.open('YourFolderOnWebsite/' + SomeDynamicVariable + '.pdf', "_blank", "fullscreen=yes");

    }
});

adding css file with jquery

Your issue is that your selector is for an anchor element <a>. You are treating the <a> tag as if it represents the page which is not the case.

$('head') will work as long as this selector is being executed by the page that needs the css.

Why not simply add the css file to the page in question. Any particular reason to attempt this dynamically from another page? I am not even familiar with a way to inject css to remote pages like this ... seems like it would be a major security hole.

ADDENDUM to your reasoning:

Then you should simply pass a parameter to the page, read it using javascript, and then do whatever is needed based on the parameter.

What does ||= (or-equals) mean in Ruby?

||= is a conditional assignment operator

  x ||= y

is equivalent to

  x = x || y

or alternatively

if defined?(x) and x
    x = x
else 
    x = y
end

pip issue installing almost any library

I solved this issue with the following steps (on sles 11sp2)

zypper remove pip
easy_install pip=1.2.1
pip install --upgrade scons

Here are the same steps in puppet (which should work on all distros)

  package { 'python-pip':
    ensure => absent,
  }
  exec { 'python-pip':
    command  => '/usr/bin/easy_install pip==1.2.1',
    require  => Package['python-pip'],
  }
  package { 'scons': 
    ensure   => latest,
    provider => pip,
    require  => Exec['python-pip'],
  }

How to update a single pod without touching other dependencies

Just a small notice.

pod update POD_NAME

will work only if this pod was already installed. Otherwise you will have to update all of them with

pod update

command

How to Convert Excel Numeric Cell Value into Words

There is no built-in formula in excel, you have to add a vb script and permanently save it with your MS. Excel's installation as Add-In.

  1. press Alt+F11
  2. MENU: (Tool Strip) Insert Module
  3. copy and paste the below code


Option Explicit

Public Numbers As Variant, Tens As Variant

Sub SetNums()
    Numbers = Array("", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine", "Ten", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen")
    Tens = Array("", "", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety")
End Sub

Function WordNum(MyNumber As Double) As String
    Dim DecimalPosition As Integer, ValNo As Variant, StrNo As String
    Dim NumStr As String, n As Integer, Temp1 As String, Temp2 As String
    ' This macro was written by Chris Mead - www.MeadInKent.co.uk
    If Abs(MyNumber) > 999999999 Then
        WordNum = "Value too large"
        Exit Function
    End If
    SetNums
    ' String representation of amount (excl decimals)
    NumStr = Right("000000000" & Trim(Str(Int(Abs(MyNumber)))), 9)
    ValNo = Array(0, Val(Mid(NumStr, 1, 3)), Val(Mid(NumStr, 4, 3)), Val(Mid(NumStr, 7, 3)))
    For n = 3 To 1 Step -1    'analyse the absolute number as 3 sets of 3 digits
        StrNo = Format(ValNo(n), "000")
        If ValNo(n) > 0 Then
            Temp1 = GetTens(Val(Right(StrNo, 2)))
            If Left(StrNo, 1) <> "0" Then
                Temp2 = Numbers(Val(Left(StrNo, 1))) & " hundred"
                If Temp1 <> "" Then Temp2 = Temp2 & " and "
            Else
                Temp2 = ""
            End If
            If n = 3 Then
                If Temp2 = "" And ValNo(1) + ValNo(2) > 0 Then Temp2 = "and "
                WordNum = Trim(Temp2 & Temp1)
            End If
            If n = 2 Then WordNum = Trim(Temp2 & Temp1 & " thousand " & WordNum)
            If n = 1 Then WordNum = Trim(Temp2 & Temp1 & " million " & WordNum)
        End If
    Next n
    NumStr = Trim(Str(Abs(MyNumber)))
    ' Values after the decimal place
    DecimalPosition = InStr(NumStr, ".")
    Numbers(0) = "Zero"
    If DecimalPosition > 0 And DecimalPosition < Len(NumStr) Then
        Temp1 = " point"
        For n = DecimalPosition + 1 To Len(NumStr)
            Temp1 = Temp1 & " " & Numbers(Val(Mid(NumStr, n, 1)))
        Next n
        WordNum = WordNum & Temp1
    End If
    If Len(WordNum) = 0 Or Left(WordNum, 2) = " p" Then
        WordNum = "Zero" & WordNum
    End If
End Function

Function GetTens(TensNum As Integer) As String
' Converts a number from 0 to 99 into text.
    If TensNum <= 19 Then
        GetTens = Numbers(TensNum)
    Else
        Dim MyNo As String
        MyNo = Format(TensNum, "00")
        GetTens = Tens(Val(Left(MyNo, 1))) & " " & Numbers(Val(Right(MyNo, 1)))
    End If
End Function

After this, From File Menu select Save Book ,from next menu select "Excel 97-2003 Add-In (*.xla)

It will save as Excel Add-In. that will be available till the Ms.Office Installation to that machine.

Now Open any Excel File in any Cell type =WordNum(<your numeric value or cell reference>)

you will see a Words equivalent of the numeric value.

This Snippet of code is taken from: http://en.kioskea.net/forum/affich-267274-how-to-convert-number-into-text-in-excel

HTML5 Video Autoplay not working correctly

//You might want to add some scripts if your software doesn't support jQuery or giving any reference type error.

//Use above scripts only if the software you are working on doesn't support jQuery.

$(document).ready(function() { //Change the location of your mp3 or any music file. var source = "../Assets/music.mp3"; var audio = new Audio(); audio.src = source; audio.autoplay = true; });

Show or hide element in React

There are several great answers already, but I don't think they've been explained very well and several of the methods given contain some gotchas that might trip people up. So I'm going to go over the three main ways (plus one off-topic option) to do this and explain the pros and cons. I'm mostly writing this because Option 1 was recommended a lot and there's a lot of potential issues with that option if not used correctly.

Option 1: Conditional Rendering in the parent.

I don't like this method unless you're only going to render the component one time and leave it there. The issue is it will cause react to create the component from scratch every time you toggle the visibility. Here's the example. LogoutButton or LoginButton are being conditionally rendered in the parent LoginControl. If you run this you'll notice the constructor is getting called on each button click. https://codepen.io/Kelnor/pen/LzPdpN?editors=1111

class LoginControl extends React.Component {
  constructor(props) {
    super(props);
    this.handleLoginClick = this.handleLoginClick.bind(this);
    this.handleLogoutClick = this.handleLogoutClick.bind(this);
    this.state = {isLoggedIn: false};
  }

  handleLoginClick() {
    this.setState({isLoggedIn: true});
  }

  handleLogoutClick() {
    this.setState({isLoggedIn: false});
  }

  render() {
    const isLoggedIn = this.state.isLoggedIn;

    let button = null;
    if (isLoggedIn) {
      button = <LogoutButton onClick={this.handleLogoutClick} />;
    } else {
      button = <LoginButton onClick={this.handleLoginClick} />;
    }

    return (
      <div>
        <Greeting isLoggedIn={isLoggedIn} />
        {button}
      </div>
    );
  }
}

class LogoutButton extends React.Component{
  constructor(props, context){
    super(props, context)
    console.log('created logout button');
  }
  render(){
    return (
      <button onClick={this.props.onClick}>
        Logout
      </button>
    );
  }
}

class LoginButton extends React.Component{
  constructor(props, context){
    super(props, context)
    console.log('created login button');
  }
  render(){
    return (
      <button onClick={this.props.onClick}>
        Login
      </button>
    );
  }
}

function UserGreeting(props) {
  return <h1>Welcome back!</h1>;
}

function GuestGreeting(props) {
  return <h1>Please sign up.</h1>;
}

function Greeting(props) {
  const isLoggedIn = props.isLoggedIn;
  if (isLoggedIn) {
    return <UserGreeting />;
  }
  return <GuestGreeting />;
}

ReactDOM.render(
  <LoginControl />,
  document.getElementById('root')
);

Now React is pretty quick at creating components from scratch. However, it still has to call your code when creating it. So if your constructor, componentDidMount, render, etc code is expensive, then it'll significantly slow down showing the component. It also means you cannot use this with stateful components where you want the state to be preserved when hidden (and restored when displayed.) The one advantage is that the hidden component isn't created at all until it's selected. So hidden components won't delay your initial page load. There may also be cases where you WANT a stateful component to reset when toggled. In which case this is your best option.

Option 2: Conditional Rendering in the child

This creates both components once. Then short circuits the rest of the render code if the component is hidden. You can also short circuit other logic in other methods using the visible prop. Notice the console.log in the codepen page. https://codepen.io/Kelnor/pen/YrKaWZ?editors=0011

class LoginControl extends React.Component {
  constructor(props) {
    super(props);
    this.handleLoginClick = this.handleLoginClick.bind(this);
    this.handleLogoutClick = this.handleLogoutClick.bind(this);
    this.state = {isLoggedIn: false};
  }

  handleLoginClick() {
    this.setState({isLoggedIn: true});
  }

  handleLogoutClick() {
    this.setState({isLoggedIn: false});
  }

  render() {
    const isLoggedIn = this.state.isLoggedIn;
    return (
      <div>
        <Greeting isLoggedIn={isLoggedIn} />
        <LoginButton isLoggedIn={isLoggedIn} onClick={this.handleLoginClick}/>
        <LogoutButton isLoggedIn={isLoggedIn} onClick={this.handleLogoutClick}/>
      </div>
    );
  }
}

class LogoutButton extends React.Component{
  constructor(props, context){
    super(props, context)
    console.log('created logout button');
  }
  render(){
    if(!this.props.isLoggedIn){
      return null;
    }
    return (
      <button onClick={this.props.onClick}>
        Logout
      </button>
    );
  }
}

class LoginButton extends React.Component{
  constructor(props, context){
    super(props, context)
    console.log('created login button');
  }
  render(){
    if(this.props.isLoggedIn){
      return null;
    }
    return (
      <button onClick={this.props.onClick}>
        Login
      </button>
    );
  }
}

function UserGreeting(props) {
  return <h1>Welcome back!</h1>;
}

function GuestGreeting(props) {
  return <h1>Please sign up.</h1>;
}

function Greeting(props) {
  const isLoggedIn = props.isLoggedIn;
  if (isLoggedIn) {
    return <UserGreeting />;
  }
  return <GuestGreeting />;
}

ReactDOM.render(
  <LoginControl />,
  document.getElementById('root')
);

Now, if the initialization logic is quick and the children are stateless, then you won't see a difference in performance or functionality. However, why make React create a brand new component every toggle anyway? If the initialization is expensive however, Option 1 will run it every time you toggle a component which will slow the page down when switching. Option 2 will run all of the component's inits on first page load. Slowing down that first load. Should note again. If you're just showing the component one time based on a condition and not toggling it, or you want it to reset when toggledm, then Option 1 is fine and probably the best option.

If slow page load is a problem however, it means you've got expensive code in a lifecycle method and that's generally not a good idea. You can, and probably should, solve the slow page load by moving the expensive code out of the lifecycle methods. Move it to an async function that's kicked off by ComponentDidMount and have the callback put it in a state variable with setState(). If the state variable is null and the component is visible then have the render function return a placeholder. Otherwise render the data. That way the page will load quickly and populate the tabs as they load. You can also move the logic into the parent and push the results to the children as props. That way you can prioritize which tabs get loaded first. Or cache the results and only run the logic the first time a component is shown.

Option 3: Class Hiding

Class hiding is probably the easiest to implement. As mentioned you just create a CSS class with display: none and assign the class based on prop. The downside is the entire code of every hidden component is called and all hidden components are attached to the DOM. (Option 1 doesn't create the hidden components at all. And Option 2 short circuits unnecessary code when the component is hidden and removes the component from the DOM completely.) It appears this is faster at toggling visibility according some tests done by commenters on other answers but I can't speak to that.

Option 4: One component but change Props. Or maybe no component at all and cache HTML.

This one won't work for every application and it's off topic because it's not about hiding components, but it might be a better solution for some use cases than hiding. Let's say you have tabs. It might be possible to write one React Component and just use the props to change what's displayed in the tab. You could also save the JSX to state variables and use a prop to decide which JSX to return in the render function. If the JSX has to be generated then do it and cache it in the parent and send the correct one as a prop. Or generate in the child and cache it in the child's state and use props to select the active one.

Show tables, describe tables equivalent in redshift

I had to select from the information schema to get details of my tables and columns; in case it helps anyone:

SELECT * FROM information_schema.tables
WHERE table_schema = 'myschema'; 

SELECT * FROM information_schema.columns
WHERE table_schema = 'myschema' AND table_name = 'mytable'; 

"error: assignment to expression with array type error" when I assign a struct field (C)

typedef struct{
     char name[30];
     char surname[30];
     int age;
} data;

defines that data should be a block of memory that fits 60 chars plus 4 for the int (see note)

[----------------------------,------------------------------,----]
 ^ this is name              ^ this is surname              ^ this is age

This allocates the memory on the stack.

data s1;

Assignments just copies numbers, sometimes pointers.

This fails

s1.name = "Paulo";

because the compiler knows that s1.name is the start of a struct 64 bytes long, and "Paulo" is a char[] 6 bytes long (6 because of the trailing \0 in C strings)
Thus, trying to assign a pointer to a string into a string.

To copy "Paulo" into the struct at the point name and "Rossi" into the struct at point surname.

memcpy(s1.name,    "Paulo", 6);
memcpy(s1.surname, "Rossi", 6);
s1.age = 1;

You end up with

[Paulo0----------------------,Rossi0-------------------------,0001]

strcpy does the same thing but it knows about \0 termination so does not need the length hardcoded.

Alternatively you can define a struct which points to char arrays of any length.

typedef struct {
  char *name;
  char *surname;
  int age;
} data;

This will create

[----,----,----]

This will now work because you are filling the struct with pointers.

s1.name = "Paulo";
s1.surname = "Rossi";
s1.age = 1;

Something like this

[---4,--10,---1]

Where 4 and 10 are pointers.

Note: the ints and pointers can be different sizes, the sizes 4 above are 32bit as an example.

CSS: how to get scrollbars for div inside container of fixed height

Code from the above answer by Dutchie432

.FixedHeightContainer {
    float:right;
    height: 250px;
    width:250px; 
    padding:3px; 
    background:#f00;
}

.Content {
    height:224px;
    overflow:auto;
    background:#fff;
}

Android studio takes too much memory

I'm currently running Android Studio on Windows 8.1 machine with 6 gigs of RAM.

I found that disabling VCS in android studio and using an external program to handle VCS helped a lot. You can disable VCS by going to File->Settings->Plugins and disable the following:

  • CVS Integration
  • Git Integration
  • GitHub
  • Google Cloud Testing
  • Google Cloud Tools Core
  • Google Cloud Tools for Android Studio
  • hg4idea
  • Subversion Integration
  • Mercurial Integration
  • TestNG-J

How do I download a file from the internet to my linux server with Bash

I guess you could use curl and wget, but since Oracle requires you to check of some checkmarks this will be painfull to emulate with the tools mentioned. You would have to download the page with the license agreement and from looking at it figure out what request is needed to get to the actual download.

Of course you could simply start a browser, but this might not qualify as 'from the command line'. So you might want to look into lynx, a text based browser.

Why has it failed to load main-class manifest attribute from a JAR file?

I'm not sure I believe your symptoms:

  • If the jre command isn't found, then running jre -cp app.jar should give the same error
  • Just adding a JAR file to the classpath shouldn't give the error you're seeing

I'd expect you to see this error if you run:

java -jar app.jar

The Main-Class header needs to be in the manifest for the JAR file - this is metadata about things like other required libraries. See the Sun documentation for how to create an appropriate manifest. Basically you need to create a text file which includes a line like this:

Main-Class: MainClass

Then run

jar cfm app.jar manifest.txt *.class

How do I POST XML data with curl

It is simpler to use a file (req.xml in my case) with content you want to send -- like this:

curl -H "Content-Type: text/xml" -d @req.xml -X POST http://localhost/asdf

You should consider using type 'application/xml', too (differences explained here)

Alternatively, without needing making curl actually read the file, you can use cat to spit the file into the stdout and make curl to read from stdout like this:

cat req.xml | curl -H "Content-Type: text/xml" -d @- -X POST http://localhost/asdf

Both examples should produce identical service output.

RabbitMQ / AMQP: single queue, multiple consumers for same message?

The last couple of answers are almost correct - I have tons of apps that generate messages that need to end up with different consumers so the process is very simple.

If you want multiple consumers to the same message, do the following procedure.

Create multiple queues, one for each app that is to receive the message, in each queue properties, "bind" a routing tag with the amq.direct exchange. Change you publishing app to send to amq.direct and use the routing-tag (not a queue). AMQP will then copy the message into each queue with the same binding. Works like a charm :)

Example: Lets say I have a JSON string I generate, I publish it to the "amq.direct" exchange using the routing tag "new-sales-order", I have a queue for my order_printer app that prints order, I have a queue for my billing system that will send a copy of the order and invoice the client and I have a web archive system where I archive orders for historic/compliance reasons and I have a client web interface where orders are tracked as other info comes in about an order.

So my queues are: order_printer, order_billing, order_archive and order_tracking All have the binding tag "new-sales-order" bound to them, all 4 will get the JSON data.

This is an ideal way to send data without the publishing app knowing or caring about the receiving apps.

Ordering by specific field value first

There's also the MySQL FIELD function.

If you want complete sorting for all possible values:

SELECT id, name, priority
FROM mytable
ORDER BY FIELD(name, "core", "board", "other")

If you only care that "core" is first and the other values don't matter:

SELECT id, name, priority
FROM mytable
ORDER BY FIELD(name, "core") DESC

If you want to sort by "core" first, and the other fields in normal sort order:

SELECT id, name, priority
FROM mytable
ORDER BY FIELD(name, "core") DESC, priority

There are some caveats here, though:

First, I'm pretty sure this is mysql-only functionality - the question is tagged mysql, but you never know.

Second, pay attention to how FIELD() works: it returns the one-based index of the value - in the case of FIELD(priority, "core"), it'll return 1 if "core" is the value. If the value of the field is not in the list, it returns zero. This is why DESC is necessary unless you specify all possible values.

What is the difference between Nexus and Maven?

Whatever I understood from my learning and what I think it is is here. I am Quoting some part from a book i learnt this things. Nexus Repository Manager and Nexus Repository Manager OSS started as a repository manager supporting the Maven repository format. While it supports many other repository formats now, the Maven repository format is still the most common and well supported format for build and provisioning tools running on the JVM and beyond. This chapter shows example configurations for using the repository manager with Apache Maven and a number of other tools. The setups take advantage of merging many repositories and exposing them via a repository group. Setting this up is documented in the chapter in addition to the configuration used by specific tools.

Details

Change windows hostname from command line

The netdom.exe command line program can be used. This is available from the Windows XP Support Tools or Server 2003 Support Tools (both on the installation CD).

Usage guidelines here

Creating a generic method in C#

You can use sort of Maybe monad (though I'd prefer Jay's answer)

public class Maybe<T>
{
    private readonly T _value;

    public Maybe(T value)
    {
        _value = value;
        IsNothing = false;
    }

    public Maybe()
    {
        IsNothing = true;
    }

    public bool IsNothing { get; private set; }

    public T Value
    {
        get
        {
            if (IsNothing)
            {
                throw new InvalidOperationException("Value doesn't exist");
            }
            return _value;
        }
    }

    public override bool Equals(object other)
    {
        if (IsNothing)
        {
            return (other == null);
        }
        if (other == null)
        {
            return false;
        }
        return _value.Equals(other);
    }

    public override int GetHashCode()
    {
        if (IsNothing)
        {
            return 0;
        }
        return _value.GetHashCode();
    }

    public override string ToString()
    {
        if (IsNothing)
        {
            return "";
        }
        return _value.ToString();
    }

    public static implicit operator Maybe<T>(T value)
    {
        return new Maybe<T>(value);
    }

    public static explicit operator T(Maybe<T> value)
    {
        return value.Value;
    }
}

Your method would look like:

    public static Maybe<T> GetQueryString<T>(string key) where T : IConvertible
    {
        if (String.IsNullOrEmpty(HttpContext.Current.Request.QueryString[key]) == false)
        {
            string value = HttpContext.Current.Request.QueryString[key];

            try
            {
                return (T)Convert.ChangeType(value, typeof(T));
            }
            catch
            {
                //Could not convert.  Pass back default value...
                return new Maybe<T>();
            }
        }

        return new Maybe<T>();
    }

How can I execute Python scripts using Anaconda's version of Python?

I know this is old, but none of the answers here is a real solution if you want to be able to double-click Python files and have the correct interpreter used without modifying your PYTHONPATH or PATH every time you want to use a different interpreter. Sure, from the command line, activate my-environment works, but OP specifically asked about double-clicking.

In this case, the correct thing to do is use the Python launcher for Windows. Then, all you have to do is add #! path\to\interpreter\python.exe to the top of your script. Unfortunately, although the launcher comes standard with Python 3.3+, it is not included with Anaconda (see Python & Windows: Where is the python launcher?), and the simplest thing to do is to install it separately from here.

How to create a new instance from a class object in Python

If you have a module with a class you want to import, you can do it like this.

module = __import__(filename)
instance = module.MyClass()

If you do not know what the class is named, you can iterate through the classes available from a module.

import inspect
module = __import__(filename)
for c in module.__dict__.values():
    if inspect.isclass(c):
        # You may need do some additional checking to ensure 
        # it's the class you want
        instance = c()

How to extract an assembly from the GAC?

I am the author of PowerShell GAC. With PowerShell GAC you can extract assemblies from the GAC without depending on GAC internals like changing folder structures.

Get-GacAssembly SomeCompany* | Get-GacAssemblyFile | Copy-Item -Dest C:\Temp\SomeCompany

How can I get sin, cos, and tan to use degrees instead of radians?

Create your own conversion function that applies the needed math, and invoke those instead. http://en.wikipedia.org/wiki/Radian#Conversion_between_radians_and_degrees

Eclipse IDE: How to zoom in on text?

The googlecode fontsupdate does not work anymore unfortunately. You can however just download the code from github:

https://github.com/gkorland/Eclipse-Fonts

Just download it as .zip, and add it in eclipse:

Adding a local plugin

Then you have the familiar buttons again!

Parse a URI String into Name-Value Collection

If you are looking for a way to achieve it without using an external library, the following code will help you.

public static Map<String, String> splitQuery(URL url) throws UnsupportedEncodingException {
    Map<String, String> query_pairs = new LinkedHashMap<String, String>();
    String query = url.getQuery();
    String[] pairs = query.split("&");
    for (String pair : pairs) {
        int idx = pair.indexOf("=");
        query_pairs.put(URLDecoder.decode(pair.substring(0, idx), "UTF-8"), URLDecoder.decode(pair.substring(idx + 1), "UTF-8"));
    }
    return query_pairs;
}

You can access the returned Map using <map>.get("client_id"), with the URL given in your question this would return "SS".

UPDATE URL-Decoding added

UPDATE As this answer is still quite popular, I made an improved version of the method above, which handles multiple parameters with the same key and parameters with no value as well.

public static Map<String, List<String>> splitQuery(URL url) throws UnsupportedEncodingException {
  final Map<String, List<String>> query_pairs = new LinkedHashMap<String, List<String>>();
  final String[] pairs = url.getQuery().split("&");
  for (String pair : pairs) {
    final int idx = pair.indexOf("=");
    final String key = idx > 0 ? URLDecoder.decode(pair.substring(0, idx), "UTF-8") : pair;
    if (!query_pairs.containsKey(key)) {
      query_pairs.put(key, new LinkedList<String>());
    }
    final String value = idx > 0 && pair.length() > idx + 1 ? URLDecoder.decode(pair.substring(idx + 1), "UTF-8") : null;
    query_pairs.get(key).add(value);
  }
  return query_pairs;
}

UPDATE Java8 version

public Map<String, List<String>> splitQuery(URL url) {
    if (Strings.isNullOrEmpty(url.getQuery())) {
        return Collections.emptyMap();
    }
    return Arrays.stream(url.getQuery().split("&"))
            .map(this::splitQueryParameter)
            .collect(Collectors.groupingBy(SimpleImmutableEntry::getKey, LinkedHashMap::new, mapping(Map.Entry::getValue, toList())));
}

public SimpleImmutableEntry<String, String> splitQueryParameter(String it) {
    final int idx = it.indexOf("=");
    final String key = idx > 0 ? it.substring(0, idx) : it;
    final String value = idx > 0 && it.length() > idx + 1 ? it.substring(idx + 1) : null;
    return new SimpleImmutableEntry<>(
        URLDecoder.decode(key, "UTF-8"),
        URLDecoder.decode(value, "UTF-8")
    );
}

Running the above method with the URL

https://stackoverflow.com?param1=value1&param2=&param3=value3&param3

returns this Map:

{param1=["value1"], param2=[null], param3=["value3", null]}

How to iterate std::set?

You must dereference the iterator in order to retrieve the member of your set.

std::set<unsigned long>::iterator it;
for (it = SERVER_IPS.begin(); it != SERVER_IPS.end(); ++it) {
    u_long f = *it; // Note the "*" here
}

If you have C++11 features, you can use a range-based for loop:

for(auto f : SERVER_IPS) {
  // use f here
}    

How to use a RELATIVE path with AuthUserFile in htaccess?

1) Note that it is considered insecure to have the .htpasswd file below the server root.

2) The docs say this about relative paths, so it looks you're out of luck:

File-path is the path to the user file. If it is not absolute (i.e., if it doesn't begin with a slash), it is treated as relative to the ServerRoot.

3) While the answers recommending the use of environment variables work perfectly fine, I would prefer to put a placeholder in the .htaccess file, or have different versions in my codebase, and have the deployment process set it all up (i. e. replace placeholders or rename / move the appropriate file).

On Java projects, I use Maven to do this type of work, on, say, PHP projects, I like to have a build.sh and / or install.sh shell script that tunes the deployed files to their environment. This decouples your codebase from the specifics of its target environment (i. e. its environment variables and configuration parameters). In general, the application should adapt to the environment, if you do it the other way around, you might run into problems once the environment also has to cater for different applications, or for completely unrelated, system-specific requirements.

How to make lists contain only distinct element in Python?

The simplest way to remove duplicates whilst preserving order is to use collections.OrderedDict (Python 2.7+).

from collections import OrderedDict
d = OrderedDict()
for x in mylist:
    d[x] = True
print d.iterkeys()

How to find out if an item is present in a std::vector?

Bear in mind that, if you're going to be doing a lot of lookups, there are STL containers that are better for that. I don't know what your application is, but associative containers like std::map may be worth considering.

std::vector is the container of choice unless you have a reason for another, and lookups by value can be such a reason.

How do I perform an insert and return inserted identity with Dapper?

It does support input/output parameters (including RETURN value) if you use DynamicParameters, but in this case the simpler option is simply:

var id = connection.QuerySingle<int>( @"
INSERT INTO [MyTable] ([Stuff]) VALUES (@Stuff);
SELECT CAST(SCOPE_IDENTITY() as int)", new { Stuff = mystuff});

Note that on more recent versions of SQL Server you can use the OUTPUT clause:

var id = connection.QuerySingle<int>( @"
INSERT INTO [MyTable] ([Stuff])
OUTPUT INSERTED.Id
VALUES (@Stuff);", new { Stuff = mystuff});

How to write a full path in a batch file having a folder name with space?

CD E:\Documents and Settings\All Users\Application Data

E:\Documents and Settings\All Users\Application Data>REGSVR32 xyz.dll

How do I upgrade to Python 3.6 with conda?

In the past, I have found it quite difficult to try to upgrade in-place.

Note: my use-case for Anaconda is as an all-in-one Python environment. I don't bother with separate virtual environments. If you're using conda to create environments, this may be destructive because conda creates environments with hard-links inside your Anaconda/envs directory.

So if you use environments, you may first want to export your environments. After activating your environment, do something like:

conda env export > environment.yml

After backing up your environments (if necessary), you may remove your old Anaconda (it's very simple to uninstall Anaconda):

$ rm -rf ~/anaconda3/

and replace it by downloading the new Anaconda, e.g. Linux, 64 bit:

$ cd ~/Downloads
$ wget https://repo.continuum.io/archive/Anaconda3-4.3.0-Linux-x86_64.sh 

(see here for a more recent one),

and then executing it:

$ bash Anaconda3-4.3.0-Linux-x86_64.sh 

Best data type for storing currency values in a MySQL database

Something like Decimal(19,4) usually works pretty well in most cases. You can adjust the scale and precision to fit the needs of the numbers you need to store. Even in SQL Server, I tend not to use "money" as it's non-standard.

How do I calculate a point on a circle’s circumference?

Here is my implementation in C#:

    public static PointF PointOnCircle(float radius, float angleInDegrees, PointF origin)
    {
        // Convert from degrees to radians via multiplication by PI/180        
        float x = (float)(radius * Math.Cos(angleInDegrees * Math.PI / 180F)) + origin.X;
        float y = (float)(radius * Math.Sin(angleInDegrees * Math.PI / 180F)) + origin.Y;

        return new PointF(x, y);
    }

How to set border on jPanel?

Swing has no idea what the preferred, minimum and maximum sizes of the GoBoard should be as you have no components inside of it for it to calculate based on, so it picks a (probably wrong) default. Since you are doing custom drawing here, you should implement these methods

Dimension getPreferredSize()
Dimension getMinumumSize()
Dimension getMaximumSize()

or conversely, call the setters for these methods.

C Macro definition to determine big endian or little endian machine?

There is no standard, but on many systems including <endian.h> will give you some defines to look for.

How to layout multiple panels on a jFrame? (java)

The JPanel is actually only a container where you can put different elements in it (even other JPanels). So in your case I would suggest one big JPanel as some sort of main container for your window. That main panel you assign a Layout that suits your needs ( here is an introduction to the layouts).

After you set the layout to your main panel you can add the paint panel and the other JPanels you want (like those with the text in it..).

  JPanel mainPanel = new JPanel();
  mainPanel.setLayout(new BoxLayout(mainPanel, BoxLayout.Y_AXIS));

  JPanel paintPanel = new JPanel();
  JPanel textPanel = new JPanel();

  mainPanel.add(paintPanel);
  mainPanel.add(textPanel);

This is just an example that sorts all sub panels vertically (Y-Axis). So if you want some other stuff at the bottom of your mainPanel (maybe some icons or buttons) that should be organized with another layout (like a horizontal layout), just create again a new JPanel as a container for all the other stuff and set setLayout(new BoxLayout(mainPanel, BoxLayout.X_AXIS).

As you will find out, the layouts are quite rigid and it may be difficult to find the best layout for your panels. So don't give up, read the introduction (the link above) and look at the pictures – this is how I do it :)

Or you can just use NetBeans to write your program. There you have a pretty easy visual editor (drag and drop) to create all sorts of Windows and Frames. (only understanding the code afterwards is ... tricky sometimes.)

EDIT

Since there are some many people interested in this question, I wanted to provide a complete example of how to layout a JFrame to make it look like OP wants it to.

The class is called MyFrame and extends swings JFrame

public class MyFrame extends javax.swing.JFrame{

    // these are the components we need.
    private final JSplitPane splitPane;  // split the window in top and bottom
    private final JPanel topPanel;       // container panel for the top
    private final JPanel bottomPanel;    // container panel for the bottom
    private final JScrollPane scrollPane; // makes the text scrollable
    private final JTextArea textArea;     // the text
    private final JPanel inputPanel;      // under the text a container for all the input elements
    private final JTextField textField;   // a textField for the text the user inputs
    private final JButton button;         // and a "send" button

    public MyFrame(){

        // first, lets create the containers:
        // the splitPane devides the window in two components (here: top and bottom)
        // users can then move the devider and decide how much of the top component
        // and how much of the bottom component they want to see.
        splitPane = new JSplitPane();

        topPanel = new JPanel();         // our top component
        bottomPanel = new JPanel();      // our bottom component

        // in our bottom panel we want the text area and the input components
        scrollPane = new JScrollPane();  // this scrollPane is used to make the text area scrollable
        textArea = new JTextArea();      // this text area will be put inside the scrollPane

        // the input components will be put in a separate panel
        inputPanel = new JPanel();
        textField = new JTextField();    // first the input field where the user can type his text
        button = new JButton("send");    // and a button at the right, to send the text

        // now lets define the default size of our window and its layout:
        setPreferredSize(new Dimension(400, 400));     // let's open the window with a default size of 400x400 pixels
        // the contentPane is the container that holds all our components
        getContentPane().setLayout(new GridLayout());  // the default GridLayout is like a grid with 1 column and 1 row,
        // we only add one element to the window itself
        getContentPane().add(splitPane);               // due to the GridLayout, our splitPane will now fill the whole window

        // let's configure our splitPane:
        splitPane.setOrientation(JSplitPane.VERTICAL_SPLIT);  // we want it to split the window verticaly
        splitPane.setDividerLocation(200);                    // the initial position of the divider is 200 (our window is 400 pixels high)
        splitPane.setTopComponent(topPanel);                  // at the top we want our "topPanel"
        splitPane.setBottomComponent(bottomPanel);            // and at the bottom we want our "bottomPanel"

        // our topPanel doesn't need anymore for this example. Whatever you want it to contain, you can add it here
        bottomPanel.setLayout(new BoxLayout(bottomPanel, BoxLayout.Y_AXIS)); // BoxLayout.Y_AXIS will arrange the content vertically

        bottomPanel.add(scrollPane);                // first we add the scrollPane to the bottomPanel, so it is at the top
        scrollPane.setViewportView(textArea);       // the scrollPane should make the textArea scrollable, so we define the viewport
        bottomPanel.add(inputPanel);                // then we add the inputPanel to the bottomPanel, so it under the scrollPane / textArea

        // let's set the maximum size of the inputPanel, so it doesn't get too big when the user resizes the window
        inputPanel.setMaximumSize(new Dimension(Integer.MAX_VALUE, 75));     // we set the max height to 75 and the max width to (almost) unlimited
        inputPanel.setLayout(new BoxLayout(inputPanel, BoxLayout.X_AXIS));   // X_Axis will arrange the content horizontally

        inputPanel.add(textField);        // left will be the textField
        inputPanel.add(button);           // and right the "send" button

        pack();   // calling pack() at the end, will ensure that every layout and size we just defined gets applied before the stuff becomes visible
    }

    public static void main(String args[]){
        EventQueue.invokeLater(new Runnable(){
            @Override
            public void run(){
                new MyFrame().setVisible(true);
            }
        });
    }
}

Please be aware that this is only an example and there are multiple approaches to layout a window. It all depends on your needs and if you want the content to be resizable / responsive. Another really good approach would be the GridBagLayout which can handle quite complex layouting, but which is also quite complex to learn.

How to interactively (visually) resolve conflicts in SourceTree / git

When the Resolve Conflicts->Content Menu are disabled, one may be on the Pending files list. We need to select the Conflicted files option from the drop down (top)

hope it helps

onclick event function in JavaScript

<script>
//$(document).ready(function () {
function showcontent() {
        document.getElementById("demo22").innerHTML = "Hello World";
}
//});// end of ready function
</script>

I had the same problem where onclick function calls would not work. I had included the function inside the usual "$(document).ready(function(){});" block used to wrap jquery scripts. Commenting this block out solved the problem.

How to set margin with jquery?

Set it with a px value. Changing the code like below should work

el.css('marginLeft', mrg + 'px');

Flutter command not found

Just revert to chsh -s /bin/bash from chsh -s /bin/zsh,

Run one command

chsh -s /bin/bash

Your facing this problem just because of you have change shell from /bash to /zsh in macOs. If you run this command again it will change the path again. So just run one command and problem solve.

How to convert a multipart file to File?

The answer by Alex78191 has worked for me.

public File getTempFile(MultipartFile multipartFile)
{

CommonsMultipartFile commonsMultipartFile = (CommonsMultipartFile) multipartFile;
FileItem fileItem = commonsMultipartFile.getFileItem();
DiskFileItem diskFileItem = (DiskFileItem) fileItem;
String absPath = diskFileItem.getStoreLocation().getAbsolutePath();
File file = new File(absPath);

//trick to implicitly save on disk small files (<10240 bytes by default)

if (!file.exists()) {
    file.createNewFile();
    multipartFile.transferTo(file);
}

return file;
}

For uploading files having size greater than 10240 bytes please change the maxInMemorySize in multipartResolver to 1MB.

<bean id="multipartResolver"
    class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<!-- setting maximum upload size t 20MB -->
<property name="maxUploadSize" value="20971520" />
<!-- max size of file in memory (in bytes) -->
<property name="maxInMemorySize" value="1048576" />
<!-- 1MB --> </bean>

Remove Top Line of Text File with PowerShell

It is not the most efficient in the world, but this should work:

get-content $file |
    select -Skip 1 |
    set-content "$file-temp"
move "$file-temp" $file -Force

Convert to/from DateTime and Time in Ruby

You'll need two slightly different conversions.

To convert from Time to DateTime you can amend the Time class as follows:

require 'date'
class Time
  def to_datetime
    # Convert seconds + microseconds into a fractional number of seconds
    seconds = sec + Rational(usec, 10**6)

    # Convert a UTC offset measured in minutes to one measured in a
    # fraction of a day.
    offset = Rational(utc_offset, 60 * 60 * 24)
    DateTime.new(year, month, day, hour, min, seconds, offset)
  end
end

Similar adjustments to Date will let you convert DateTime to Time .

class Date
  def to_gm_time
    to_time(new_offset, :gm)
  end

  def to_local_time
    to_time(new_offset(DateTime.now.offset-offset), :local)
  end

  private
  def to_time(dest, method)
    #Convert a fraction of a day to a number of microseconds
    usec = (dest.sec_fraction * 60 * 60 * 24 * (10**6)).to_i
    Time.send(method, dest.year, dest.month, dest.day, dest.hour, dest.min,
              dest.sec, usec)
  end
end

Note that you have to choose between local time and GM/UTC time.

Both the above code snippets are taken from O'Reilly's Ruby Cookbook. Their code reuse policy permits this.

Display Adobe pdf inside a div

You can use the Javascript library PDF.JS to display a PDF inside a div. The size of the PDF can be adjusted according to the size of the div. You can also setup event handlers for moving to next / previous pages of the PDF.

You can checkout PDF.JS Tutorial - How to display a PDF with Javascript to see how PDF.JS can be integrated in your HTML code.

How do I find the number of arguments passed to a Bash script?

to add the original reference:

You can get the number of arguments from the special parameter $#. Value of 0 means "no arguments". $# is read-only.

When used in conjunction with shift for argument processing, the special parameter $# is decremented each time Bash Builtin shift is executed.

see Bash Reference Manual in section 3.4.2 Special Parameters:

  • "The shell treats several parameters specially. These parameters may only be referenced"

  • and in this section for keyword $# "Expands to the number of positional parameters in decimal."

Connect HTML page with SQL server using javascript

<script>
var name=document.getElementById("name").value;
var address= document.getElementById("address").value;
var age= document.getElementById("age").value;

$.ajax({
      type:"GET",
      url:"http://hostname/projectfolder/webservicename.php?callback=jsondata&web_name="+name+"&web_address="+address+"&web_age="+age,
      crossDomain:true,
      dataType:'jsonp',
      success: function jsondata(data)
           {

            var parsedata=JSON.parse(JSON.stringify(data));
            var logindata=parsedata["Status"];

            if("sucess"==logindata)
            {   
                alert("success");
            }
            else
            {
                alert("failed");
            }
          }  
    }); 
<script>

You need to use web services. In the above code I have php web service to be used which has a callback function which is optional. Assuming you know HTML5 I did not post the html code. In the url you can send the details to the web server.

Nested attributes unpermitted parameters

From the docs

To whitelist an entire hash of parameters, the permit! method can be used

params.require(:log_entry).permit!

Nested attributes are in the form of a hash. In my app, I have a Question.rb model accept nested attributes for an Answer.rb model (where the user creates answer choices for a question he creates). In the questions_controller, I do this

  def question_params

      params.require(:question).permit!

  end

Everything in the question hash is permitted, including the nested answer attributes. This also works if the nested attributes are in the form of an array.

Having said that, I wonder if there's a security concern with this approach because it basically permits anything that's inside the hash without specifying exactly what it is, which seems contrary to the purpose of strong parameters.

How to initialize a private static const map in C++?

#include <map>
using namespace std;

struct A{
    static map<int,int> create_map()
        {
          map<int,int> m;
          m[1] = 2;
          m[3] = 4;
          m[5] = 6;
          return m;
        }
    static const map<int,int> myMap;

};

const map<int,int> A:: myMap =  A::create_map();

int main() {
}

How to copy commits from one branch to another?

You should really have a workflow that lets you do this all by merging:

- x - x - x (v2) - x - x - x (v2.1)
           \
            x - x - x (wss)

So all you have to do is git checkout v2.1 and git merge wss. If for some reason you really can't do this, and you can't use git rebase to move your wss branch to the right place, the command to grab a single commit from somewhere and apply it elsewhere is git cherry-pick. Just check out the branch you want to apply it on, and run git cherry-pick <SHA of commit to cherry-pick>.

Some of the ways rebase might save you:

If your history looks like this:

- x - x - x (v2) - x - x - x (v2.1)
           \
            x - x - x (v2-only) - x - x - x (wss)

You could use git rebase --onto v2 v2-only wss to move wss directly onto v2:

- x - x - x (v2) - x - x - x (v2.1)
          |\
          |  x - x - x (v2-only)
           \
             x - x - x (wss)

Then you can merge! If you really, really, really can't get to the point where you can merge, you can still use rebase to effectively do several cherry-picks at once:

# wss-starting-point is the SHA1/branch immediately before the first commit to rebase
git branch wss-to-rebase wss
git rebase --onto v2.1 wss-starting-point wss-to-rebase
git checkout v2.1
git merge wss-to-rebase

Note: the reason that it takes some extra work in order to do this is that it's creating duplicate commits in your repository. This isn't really a good thing - the whole point of easy branching and merging is to be able to do everything by making commit(s) one place and merging them into wherever they're needed. Duplicate commits mean an intent never to merge those two branches (if you decide you want to later, you'll get conflicts).

Comparing chars in Java

you can use this:

if ("ABCDEFGHIJKLMNOPQRSTUVWXYZ".contains(String.valueOf(yourChar)))

note that you do not need to create a separate String with the letters A-Z.

What is the dual table in Oracle?

It's the special table in Oracle. I often use it for calculations or checking system variables. For example:

  • Select 2*4 from dual prints out the result of the calculation
  • Select sysdate from dual prints the server current date.

How to create table using select query in SQL Server?

select <column list> into <table name> from <source> where <whereclause>

How to loop an object in React?

You can use it in a more compact way as:

var tifs = {1: 'Joe', 2: 'Jane'};
...

return (
   <select id="tif" name="tif" onChange={this.handleChange}>  
      { Object.entries(tifs).map((t,k) => <option key={k} value={t[0]}>{t[1]}</option>) }          
   </select>
)

And another slightly different flavour:

 Object.entries(tifs).map(([key,value],i) => <option key={i} value={key}>{value}</option>)  

dynamically set iframe src

Try this...

function urlChange(url) {
    var site = url+'?toolbar=0&amp;navpanes=0&amp;scrollbar=0';
    document.getElementById('iFrameName').src = site;
}

<a href="javascript:void(0);" onClick="urlChange('www.mypdf.com/test.pdf')">TEST </a>

How do I extract part of a string in t-sql

substring(field, 1,3) will work on your examples.

select substring(field, 1,3) from table

Also, if the alphabetic part is of variable length, you can do this to extract the alphabetic part:

select substring(field, 1, PATINDEX('%[1234567890]%', field) -1) 
from table
where PATINDEX('%[1234567890]%', field) > 0

Enabling SSL with XAMPP

You can also configure your SSL in xampp/apache/conf/extra/httpd-vhost.conf like this:

<VirtualHost *:443>
    DocumentRoot C:/xampp/htdocs/yourProject
    ServerName yourProject.whatever
    SSLEngine on
    SSLCertificateFile "conf/ssl.crt/server.crt"
    SSLCertificateKeyFile "conf/ssl.key/server.key"
</VirtualHost>

I guess, it's better not change it in the httpd-ssl.conf if you have more than one project and you need SSL on more than one of them

One DbContext per web request... why?

I'm pretty certain it is because the DbContext is not at all thread safe. So sharing the thing is never a good idea.

How to style CSS role

Sure you can do in this mode:

 #content[role="main"]{
       //style
    }

http://www.w3.org/TR/selectors/#attribute-selectors

Already defined in .obj - no double inclusions

I do recomend doing it in 2 filles (.h .cpp) But if u lazy just add inline before the function So it will look something like this

inline void functionX() 
{ }

more about inline functions:

The inline functions are a C++ enhancement feature to increase the execution time of a program. Functions can be instructed to compiler to make them inline so that compiler can replace those function definition wherever those are being called. Compiler replaces the definition of inline functions at compile time instead of referring function definition at runtime. NOTE- This is just a suggestion to compiler to make the function inline, if function is big (in term of executable instruction etc) then, compiler can ignore the “inline” request and treat the function as normal function.

more info here

Change the image source on rollover using jQuery

If the solution you are looking for is for an animated button, then the best you can do to improve in performance is the combination of sprites and CSS. A sprite is a huge image that contains all the images from your site (header, logo, buttons, and all decorations you have). Each image you have uses an HTTP request, and the more HTTP requests the more time it will take to load.

.buttonClass {
    width: 25px;
    height: 25px;
    background: url(Sprite.gif) -40px -500px;
}
.buttonClass:hover {
    width: 25px;
    height: 25px;
    background: url(Sprite.gif) -40px -525px;
}

The 0px 0px coordinates will be the left upper corner from your sprites.

But if you are developing some photo album with Ajax or something like that, then JavaScript (or any framework) is the best.

Have fun!

How to escape single quotes within single quoted strings

If you have GNU Parallel installed you can use its internal quoting:

$ parallel --shellquote
L's 12" record
<Ctrl-D>
'L'"'"'s 12" record'
$ echo 'L'"'"'s 12" record'
L's 12" record

From version 20190222 you can even --shellquote multiple times:

$ parallel --shellquote --shellquote --shellquote
L's 12" record
<Ctrl-D>
'"'"'"'"'"'"'L'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'s 12" record'"'"'"'"'"'"'
$ eval eval echo '"'"'"'"'"'"'L'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'s 12" record'"'"'"'"'"'"'
L's 12" record

It will quote the string in all supported shells (not only bash).

UPDATE multiple tables in MySQL using LEFT JOIN

UPDATE  t1
LEFT JOIN
        t2
ON      t2.id = t1.id
SET     t1.col1 = newvalue
WHERE   t2.id IS NULL

Note that for a SELECT it would be more efficient to use NOT IN / NOT EXISTS syntax:

SELECT  t1.*
FROM    t1
WHERE   t1.id NOT IN
        (
        SELECT  id
        FROM    t2
        )

See the article in my blog for performance details:

Unfortunately, MySQL does not allow using the target table in a subquery in an UPDATE statement, that's why you'll need to stick to less efficient LEFT JOIN syntax.

Parsing JSON object in PHP using json_decode

If you use the following instead:

$json = file_get_contents($url);
$data = json_decode($json, TRUE);

The TRUE returns an array instead of an object.

Create stacked barplot where each stack is scaled to sum to 100%

prop.table is a nice friendly way of obtaining proportions of tables.

m <- matrix(1:4,2)

 m
     [,1] [,2]
[1,]    1    3
[2,]    2    4

Leaving margin blank gives you proportions of the whole table

 prop.table(m, margin=NULL)
     [,1] [,2]
[1,]  0.1  0.3
[2,]  0.2  0.4

Giving it 1 gives you row proportions

 prop.table(m, 1)
      [,1]      [,2]
[1,] 0.2500000 0.7500000
[2,] 0.3333333 0.6666667

And 2 is column proportions

 prop.table(m, 2)
          [,1]      [,2]
[1,] 0.3333333 0.4285714
[2,] 0.6666667 0.5714286

PHP convert XML to JSON

Looks like the $state->name variable is holding an array. You can use

var_dump($state)

inside the foreach to test that.

If that's the case, you can change the line inside the foreach to

$states[]= array('state' => array_shift($state->name)); 

to correct it.

Eclipse HotKey: how to switch between tabs?

How can I switch between opened windows in Eclipse

CTRL+F7 works here - Eclipse Photon on Windows.

Avoiding NullPointerException in Java

This is a very common problem for every Java developer. So there is official support in Java 8 to address these issues without cluttered code.

Java 8 has introduced java.util.Optional<T>. It is a container that may or may not hold a non-null value. Java 8 has given a safer way to handle an object whose value may be null in some of the cases. It is inspired from the ideas of Haskell and Scala.

In a nutshell, the Optional class includes methods to explicitly deal with the cases where a value is present or absent. However, the advantage compared to null references is that the Optional<T> class forces you to think about the case when the value is not present. As a consequence, you can prevent unintended null pointer exceptions.

In above example we have a home service factory that returns a handle to multiple appliances available in the home. But these services may or may not be available/functional; it means it may result in a NullPointerException. Instead of adding a null if condition before using any service, let's wrap it in to Optional<Service>.

WRAPPING TO OPTION<T>

Let's consider a method to get a reference of a service from a factory. Instead of returning the service reference, wrap it with Optional. It lets the API user know that the returned service may or may not available/functional, use defensively

public Optional<Service> getRefrigertorControl() {
      Service s = new  RefrigeratorService();
       //...
      return Optional.ofNullable(s);
   }

As you see Optional.ofNullable() provides an easy way to get the reference wrapped. There are another ways to get the reference of Optional, either Optional.empty() & Optional.of(). One for returning an empty object instead of retuning null and the other to wrap a non-nullable object, respectively.

SO HOW EXACTLY IT HELPS TO AVOID A NULL CHECK?

Once you have wrapped a reference object, Optional provides many useful methods to invoke methods on a wrapped reference without NPE.

Optional ref = homeServices.getRefrigertorControl();
ref.ifPresent(HomeServices::switchItOn);

Optional.ifPresent invokes the given Consumer with a reference if it is a non-null value. Otherwise, it does nothing.

@FunctionalInterface
public interface Consumer<T>

Represents an operation that accepts a single input argument and returns no result. Unlike most other functional interfaces, Consumer is expected to operate via side-effects. It is so clean and easy to understand. In the above code example, HomeService.switchOn(Service) gets invoked if the Optional holding reference is non-null.

We use the ternary operator very often for checking null condition and return an alternative value or default value. Optional provides another way to handle the same condition without checking null. Optional.orElse(defaultObj) returns defaultObj if the Optional has a null value. Let's use this in our sample code:

public static Optional<HomeServices> get() {
    service = Optional.of(service.orElse(new HomeServices()));
    return service;
}

Now HomeServices.get() does same thing, but in a better way. It checks whether the service is already initialized of not. If it is then return the same or create a new New service. Optional<T>.orElse(T) helps to return a default value.

Finally, here is our NPE as well as null check-free code:

import java.util.Optional;
public class HomeServices {
    private static final int NOW = 0;
    private static Optional<HomeServices> service;

public static Optional<HomeServices> get() {
    service = Optional.of(service.orElse(new HomeServices()));
    return service;
}

public Optional<Service> getRefrigertorControl() {
    Service s = new  RefrigeratorService();
    //...
    return Optional.ofNullable(s);
}

public static void main(String[] args) {
    /* Get Home Services handle */
    Optional<HomeServices> homeServices = HomeServices.get();
    if(homeServices != null) {
        Optional<Service> refrigertorControl = homeServices.get().getRefrigertorControl();
        refrigertorControl.ifPresent(HomeServices::switchItOn);
    }
}

public static void switchItOn(Service s){
         //...
    }
}

The complete post is NPE as well as Null check-free code … Really?.

How do I comment out a block of tags in XML?

Here for commenting we have to write like below:

<!-- Your comment here -->

Shortcuts for IntelliJ Idea and Eclipse

For Windows & Linux:

Shortcut for Commenting a single line:

Ctrl + /

Shortcut for Commenting multiple lines:

Ctrl + Shift + /

For Mac:

Shortcut for Commenting a single line:

cmnd + /

Shortcut for Commenting multiple lines:

cmnd + Shift + /

One thing you have to keep in mind that, you can't comment an attribute of an XML tag. For Example:

<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    <!--android:text="Hello.."-->
    android:textStyle="bold" />

Here, TextView is a XML Tag and text is an attribute of that tag. You can't comment attributes of an XML Tag. You have to comment the full XML Tag. For Example:

<!--<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="Hello.."
    android:textStyle="bold" />-->

PHP: How to generate a random, unique, alphanumeric string for use in a secret link?

If you want to generate a unique string in PHP, try following.

md5(uniqid().mt_rand());

In this,

uniqid() - It will generate unique string. This function returns timestamp based unique identifier as a string.

mt_rand() - Generate random number.

md5() - It will generate the hash string.

Use Awk to extract substring

You do not need any external command at all, just use Parameter Expansion in bash:

hostname=aaa0.bbb.ccc
echo ${hostname%%.*}

Open file with associated application

This is an old thread but just in case anyone comes across it like I did. pi.FileName needs to be set to the file name (and possibly full path to file ) of the executable you want to use to open your file. The below code works for me to open a video file with VLC.

var path = files[currentIndex].fileName;
var pi = new ProcessStartInfo(path)
{
    Arguments = Path.GetFileName(path),
    UseShellExecute = true,
    WorkingDirectory = Path.GetDirectoryName(path),
    FileName = "C:\\Program Files (x86)\\VideoLAN\\VLC\\vlc.exe",
    Verb = "OPEN"
};
Process.Start(pi)

Tigran's answer works but will use windows' default application to open your file, so using ProcessStartInfo may be useful if you want to open the file with an application that is not the default.

Remove columns from dataframe where ALL values are NA

df[sapply(df, function(x) all(is.na(x)))] <- NULL

Facebook database design?

My best bet is that they created a graph structure. The nodes are users and "friendships" are edges.

Keep one table of users, keep another table of edges. Then you can keep data about the edges, like "day they became friends" and "approved status," etc.

Retrofit 2 - URL Query Parameter

If you specify @GET("foobar?a=5"), then any @Query("b") must be appended using &, producing something like foobar?a=5&b=7.

If you specify @GET("foobar"), then the first @Query must be appended using ?, producing something like foobar?b=7.

That's how Retrofit works.

When you specify @GET("foobar?"), Retrofit thinks you already gave some query parameter, and appends more query parameters using &.

Remove the ?, and you will get the desired result.

How to add an item to an ArrayList in Kotlin?

For people just migrating from java, In Kotlin List is by default immutable and mutable version of Lists is called MutableList.

Hence if you have something like :

val list: List<String> = ArrayList()

In this case you will not get an add() method as list is immutable. Hence you will have to declare a MutableList as shown below :

val list: MutableList<String> = ArrayList()

Now you will see an add() method and you can add elements to any list.

Why use $_SERVER['PHP_SELF'] instead of ""

In addition to above answers, another way of doing it is $_SERVER['PHP_SELF'] or simply using an empty string is to use __DIR__.
OR
If you're on a lower PHP version (<5.3), a more common alternative is to use dirname(__FILE__)
Both returns the folder name of the file in context.

EDIT
As Boann pointed out that this returns the on-disk location of the file. WHich you would not ideally expose as a url. In that case dirname($_SERVER['PHP_SELF']) can return the folder name of the file in context.

How to grep with a list of words

To find a very long list of words in big files, it can be more efficient to use egrep:

remove the last \n of A
$ tr '\n' '|' < A > A_regex
$ egrep -f A_regex B

Finding the index of elements based on a condition using python list comprehension

Even if it's a late answer: I think this is still a very good question and IMHO Python (without additional libraries or toolkits like numpy) is still lacking a convenient method to access the indices of list elements according to a manually defined filter.

You could manually define a function, which provides that functionality:

def indices(list, filtr=lambda x: bool(x)):
    return [i for i,x in enumerate(list) if filtr(x)]

print(indices([1,0,3,5,1], lambda x: x==1))

Yields: [0, 4]

In my imagination the perfect way would be making a child class of list and adding the indices function as class method. In this way only the filter method would be needed:

class MyList(list):
    def __init__(self, *args):
        list.__init__(self, *args)
    def indices(self, filtr=lambda x: bool(x)):
        return [i for i,x in enumerate(self) if filtr(x)]

my_list = MyList([1,0,3,5,1])
my_list.indices(lambda x: x==1)

I elaborated a bit more on that topic here: http://tinyurl.com/jajrr87

How to iterate over a column vector in Matlab?

for i=1:length(list)
  elm = list(i);
  //do something with elm.

Uncaught TypeError: (intermediate value)(...) is not a function

When I create a root class, whose methods I defined using the arrow functions. When inheriting and overwriting the original function I noticed the same issue.

class C {
  x = () => 1; 
 };
 
class CC extends C {
  x = (foo) =>  super.x() + foo;
};

let add = new CC;
console.log(add.x(4));

this is solved by defining the method of the parent class without arrow functions

class C {
  x() { 
    return 1; 
  }; 
 };
 
class CC extends C {
  x = foo =>  super.x() + foo;
};

let add = new CC;
console.log(add.x(4));

Set the absolute position of a view

My code for Xamarin, I am using FrameLayout for this purpose and following is my code:

               List<object> content = new List<object>();

        object aWebView = new {ContentType="web",Width="300", Height = "300",X="10",Y="30",ContentUrl="http://www.google.com" };
        content.Add(aWebView);
        object aWebView2 = new { ContentType = "image", Width = "300", Height = "300", X = "20", Y = "40", ContentUrl = "https://www.nasa.gov/sites/default/files/styles/image_card_4x3_ratio/public/thumbnails/image/leisa_christmas_false_color.png?itok=Jxf0IlS4" };
        content.Add(aWebView2);
        FrameLayout myLayout = (FrameLayout)FindViewById(Resource.Id.frameLayout1);
        foreach (object item in content)
        {

            string contentType = item.GetType().GetProperty("ContentType").GetValue(item, null).ToString();
            FrameLayout.LayoutParams param = new FrameLayout.LayoutParams(Convert.ToInt32(item.GetType().GetProperty("Width").GetValue(item, null).ToString()), Convert.ToInt32(item.GetType().GetProperty("Height").GetValue(item, null).ToString()));
            param.LeftMargin = Convert.ToInt32(item.GetType().GetProperty("X").GetValue(item, null).ToString());
            param.TopMargin = Convert.ToInt32(item.GetType().GetProperty("Y").GetValue(item, null).ToString());

            switch (contentType) {
                case "web":{
                        WebView webview = new WebView(this);

                        //webview.hei;
                        myLayout.AddView(webview, param);
                        webview.SetWebViewClient(new WebViewClient());
                        webview.LoadUrl(item.GetType().GetProperty("ContentUrl").GetValue(item, null).ToString());

                        break;
                    }
                case "image":
                    {
                        ImageView imageview = new ImageView(this);

                        //webview.hei;
                        myLayout.AddView(imageview, param);
                        var imageBitmap =  GetImageBitmapFromUrl("https://www.nasa.gov/sites/default/files/styles/image_card_4x3_ratio/public/thumbnails/image/leisa_christmas_false_color.png?itok=Jxf0IlS4");
                        imageview.SetImageBitmap(imageBitmap);


                        break;
                    }

            }

        }

It was useful for me because I needed the property of view to overlap each other on basis of their appearance, e.g the views get stacked one above other.

Now() function with time trim

You could also use Format$(Now(), "Short Date") or whatever date format you want. Be aware, this function will return the Date as a string, so using Date() is a better approach.

How to create a button programmatically?

For Swift 5 just the same as Swift 4

 let button = UIButton()
 button.frame = CGRect(x: self.view.frame.size.width - 60, y: 60, width: 50, height: 50)
 button.backgroundColor = UIColor.red
 button.setTitle("Name your Button ", for: .normal)
 button.addTarget(self, action: #selector(buttonAction), for: .touchUpInside)
 self.view.addSubview(button)

 @objc func buttonAction(sender: UIButton!) {
    print("Button tapped")
 }

EPPlus - Read Excel Table

Not sure why but none of the above solution work for me. So sharing what worked:

public void readXLS(string FilePath)
{
    FileInfo existingFile = new FileInfo(FilePath);
    using (ExcelPackage package = new ExcelPackage(existingFile))
    {
        //get the first worksheet in the workbook
        ExcelWorksheet worksheet = package.Workbook.Worksheets[1];
        int colCount = worksheet.Dimension.End.Column;  //get Column Count
        int rowCount = worksheet.Dimension.End.Row;     //get row count
        for (int row = 1; row <= rowCount; row++)
        {
            for (int col = 1; col <= colCount; col++)
            {
                Console.WriteLine(" Row:" + row + " column:" + col + " Value:" + worksheet.Cells[row, col].Value?.ToString().Trim());
            }
        }
    }
}

What is the garbage collector in Java?

The garbage collector allows your computer to simulate a computer with infinite memory. The rest is just mechanism.

It does this by detecting when chunks of memory are no longer accessible from your code, and returning those chunks to the free store.

EDIT: Yes, the link is for C#, but C# and Java are identical in this regard.

How to change progress bar's progress color in Android

It seems that an indeterminate linear progress indicator can be made multicolor in newer versions of material design library.

Making animation type of the progress bar contiguous achieves this.

  • In the layout with this attribute:
    app:indeterminateAnimationType
    
  • or programmatically with this method:
    setIndeterminateAnimationType()
    

Refer here for more info.

WCF Service Client: The content type text/html; charset=utf-8 of the response message does not match the content type of the binding

In my WCF serive project this issue is due to Reference of System.Web.Mvc.dll 's different version. So it may be compatibility issue of DLL's different version

When I use

System.Web.Mvc.dll version 5.2.2.0 -> it thorows the Error The content type text/html; charset=utf-8 of the response message

but when I use System.Web.Mvc.dll version 4.0.0.0 or lower -> it works fine.

I don't know the reason of different version DLL's issue but by changing the DLL's verison it works for me.

This Error even generate when you add reference of other Project in your WCF Project and this reference project has different version of System.Web.Mvc DLL or could be any other DLL.

Delete ActionLink with confirm dialog

I wanted the same thing; a delete button on my Details view. I eventually realised I needed to post from that view:

@using (Html.BeginForm())
        {
            @Html.AntiForgeryToken()
            @Html.HiddenFor(model => model.Id)
            @Html.ActionLink("Edit", "Edit", new { id = Model.Id }, new { @class = "btn btn-primary", @style="margin-right:30px" })

            <input type="submit" value="Delete" class="btn btn-danger" onclick="return confirm('Are you sure you want to delete this record?');" />
        }

And, in the Controller:

 // this action deletes record - called from the Delete button on Details view
    [HttpPost]
    public ActionResult Details(MainPlus mainPlus)
    {
        if (mainPlus != null)
        {
            try
            {
                using (IDbConnection db = new SqlConnection(PCALConn))
                {
                    var result = db.Execute("DELETE PCAL.Main WHERE Id = @Id", new { Id = mainPlus.Id });
                }
                return RedirectToAction("Calls");
            } etc

SQL Server 2008: how do I grant privileges to a username?

Like the following. It will make the user database owner.

EXEC sp_addrolemember N'db_owner', N'USerNAme'

How to remove an element from a list by index

pop is also useful to remove and keep an item from a list. Where del actually trashes the item.

>>> x = [1, 2, 3, 4]

>>> p = x.pop(1)
>>> p
    2

Seeding the random number generator in Javascript

No, it is not possible to seed Math.random(), but it's fairly easy to write your own generator, or better yet, use an existing one.

Check out: this related question.

Also, see David Bau's blog for more information on seeding.

Authentication failed to bitbucket

I had the same problem. You need to go and add an app password for sourcetree in your bitbucket settings. Click "Bitbucket settings" in menu, App passwords, create app password. Then go to SourceTree and edit your saved password

How to use multiple @RequestMapping annotations in spring?

Doesn't need to. RequestMapping annotation supports wildcards and ant-style paths. Also looks like you just want a default view, so you can put

<mvc:view-controller path="/" view-name="welcome"/>

in your config file. That will forward all requests to the Root to the welcome view.

How do I link to part of a page? (hash?)

Here is how:

<a href="#go_middle">Go Middle</a>

<div id="go_middle">Hello There</div>

jQuery .val change doesn't change input value

Use attr instead.
$('#link').attr('value', 'new value');

demo

MVC Calling a view from a different controller

To directly answer your question if you want to return a view that belongs to another controller you simply have to specify the name of the view and its folder name.

public class CommentsController : Controller
{
    public ActionResult Index()
    { 
        return View("../Articles/Index", model );
    }
}

and

public class ArticlesController : Controller
{
    public ActionResult Index()
    { 
        return View();
    }
}

Also, you're talking about using a read and write method from one controller in another. I think you should directly access those methods through a model rather than calling into another controller as the other controller probably returns html.

MVC : The parameters dictionary contains a null entry for parameter 'k' of non-nullable type 'System.Int32'

It appears that you are using the default route which is defined as this:

routes.MapRoute(
    name: "Default",
    url: "{controller}/{action}/{id}",
    defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);

The key part of that route is the {id} piece. If you look at your action method, your parameter is k instead of id. You need to change your action method to this so that it matches the route parameter:

// change int k to int id
public ActionResult DetailsData(int id)

If you wanted to leave your parameter as k, then you would change the URL to be:

http://localhost:7317/Employee/DetailsData?k=4

You also appear to have a problem with your connection string. In your web.config, you need to change your connection string to this (provided by haim770 in another answer that he deleted):

<connectionStrings>
  <add name="EmployeeContext"
       connectionString="Server=.;Database=mytry;integrated security=True;"
       providerName="System.Data.SqlClient" />
</connectionStrings>

Telling gcc directly to link a library statically

You can add .a file in the linking command:

  gcc yourfiles /path/to/library/libLIBRARY.a

But this is not talking with gcc driver, but with ld linker as options like -Wl,anything are.

When you tell gcc or ld -Ldir -lLIBRARY, linker will check both static and dynamic versions of library (you can see a process with -Wl,--verbose). To change order of library types checked you can use -Wl,-Bstatic and -Wl,-Bdynamic. Here is a man page of gnu LD: http://linux.die.net/man/1/ld

To link your program with lib1, lib3 dynamically and lib2 statically, use such gcc call:

gcc program.o -llib1 -Wl,-Bstatic -llib2 -Wl,-Bdynamic -llib3

Assuming that default setting of ld is to use dynamic libraries (it is on Linux).

Custom "confirm" dialog in JavaScript?

_x000D_
_x000D_
var confirmBox = '<div class="modal fade confirm-modal">' +_x000D_
    '<div class="modal-dialog modal-sm" role="document">' +_x000D_
    '<div class="modal-content">' +_x000D_
    '<button type="button" class="close m-4 c-pointer" data-dismiss="modal" aria-label="Close">' +_x000D_
    '<span aria-hidden="true">&times;</span>' +_x000D_
    '</button>' +_x000D_
    '<div class="modal-body pb-5"></div>' +_x000D_
    '<div class="modal-footer pt-3 pb-3">' +_x000D_
    '<a href="#" class="btn btn-primary yesBtn btn-sm">OK</a>' +_x000D_
    '<button type="button" class="btn btn-secondary abortBtn btn-sm" data-dismiss="modal">Abbrechen</button>' +_x000D_
    '</div>' +_x000D_
    '</div>' +_x000D_
    '</div>' +_x000D_
    '</div>';_x000D_
_x000D_
var dialog = function(el, text, trueCallback, abortCallback) {_x000D_
_x000D_
    el.click(function(e) {_x000D_
_x000D_
        var thisConfirm = $(confirmBox).clone();_x000D_
_x000D_
        thisConfirm.find('.modal-body').text(text);_x000D_
_x000D_
        e.preventDefault();_x000D_
        $('body').append(thisConfirm);_x000D_
        $(thisConfirm).modal('show');_x000D_
_x000D_
        if (abortCallback) {_x000D_
            $(thisConfirm).find('.abortBtn').click(function(e) {_x000D_
                e.preventDefault();_x000D_
                abortCallback();_x000D_
                $(thisConfirm).modal('hide');_x000D_
            });_x000D_
        }_x000D_
_x000D_
        if (trueCallback) {_x000D_
            $(thisConfirm).find('.yesBtn').click(function(e) {_x000D_
                e.preventDefault();_x000D_
                trueCallback();_x000D_
                $(thisConfirm).modal('hide');_x000D_
            });_x000D_
        } else {_x000D_
_x000D_
            if (el.prop('nodeName') == 'A') {_x000D_
                $(thisConfirm).find('.yesBtn').attr('href', el.attr('href'));_x000D_
            }_x000D_
_x000D_
            if (el.attr('type') == 'submit') {_x000D_
                $(thisConfirm).find('.yesBtn').click(function(e) {_x000D_
                    e.preventDefault();_x000D_
                    el.off().click();_x000D_
                });_x000D_
            }_x000D_
        }_x000D_
_x000D_
        $(thisConfirm).on('hidden.bs.modal', function(e) {_x000D_
            $(this).remove();_x000D_
        });_x000D_
_x000D_
    });_x000D_
}_x000D_
_x000D_
// custom confirm_x000D_
$(function() {_x000D_
    $('[data-confirm]').each(function() {_x000D_
        dialog($(this), $(this).attr('data-confirm'));_x000D_
    });_x000D_
_x000D_
    dialog($('#customCallback'), "dialog with custom callback", function() {_x000D_
_x000D_
        alert("hi there");_x000D_
_x000D_
    });_x000D_
_x000D_
});
_x000D_
.test {_x000D_
  display:block;_x000D_
  padding: 5p 10px;_x000D_
  background:orange;_x000D_
  color:white;_x000D_
  border-radius:4px;_x000D_
  margin:0;_x000D_
  border:0;_x000D_
  width:150px;_x000D_
  text-align:center;_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_
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet"/>_x000D_
_x000D_
_x000D_
example 1_x000D_
<a class="test" href="http://example" data-confirm="do you want really leave the website?">leave website</a><br><br>_x000D_
_x000D_
_x000D_
example 2_x000D_
<form action="">_x000D_
<button class="test" type="submit" data-confirm="send form to delete some files?">delete some files</button>_x000D_
</form><br><br>_x000D_
_x000D_
example 3_x000D_
<span class="test"  id="customCallback">with callback</span>
_x000D_
_x000D_
_x000D_

Force page scroll position to top at page refresh in HTML

I found that these CSS styles force the page to always scroll to top on reload/refresh:

html {
    height: 100%;
    overflow: hidden;
    width: 100%;
}

body {
    height: 100%;
    overflow-x: hidden;
    overflow-y: auto;
    width: 100%;
}

CakePHP select default value in SELECT input

In CakePHP 1.3, use 'default'=>value to select the default value in a select input:

$this->Form->input('Leaf.id', array('type'=>'select', 'label'=>'Leaf', 'options'=>$leafs, 'default'=>'3'));

Change all files and folders permissions of a directory to 644/755

The easiest way is to do:

chmod -R u+rwX,go+rX,go-w /path/to/dir

which basically means:

to change file modes -Recursively by giving:

  • user: read, write and eXecute permissions,
  • group and other users: read and eXecute permissions, but not -write permission.

Please note that X will make a directory executable, but not a file, unless it's already searchable/executable.

+X - make a directory or file searchable/executable by everyone if it is already searchable/executable by anyone.

Please check man chmod for more details.

See also: How to chmod all directories except files (recursively)? at SU

ASP.NET MVC3 Razor - Html.ActionLink style

VB sample:

 @Html.ActionLink("Home", "Index", Nothing, New With {.style = "font-weight:bold;", .class = "someClass"})

Sample Css:

.someClass
{
    color: Green !important;
}

In my case, I found that I need the !important attribute to over ride the site.css a:link css class

Convert string to JSON array

It's a very simple way to convert:

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import com.google.gson.Gson;
import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonParser;


class Usuario {
private String username;
private String email;
private Integer credits;
private String twitter_username;

public String getUsername() {
    return username;
}

public void setUsername(String username) {
    this.username = username;
}

public String getEmail() {
    return email;
}

public void setEmail(String email) {
    this.email = email;
}

public Integer getCredits() {
    return credits;
}

public void setCredits(Integer credits) {
    this.credits = credits;
}

public String getTwitter_username() {
    return twitter_username;
}

public void setTwitter_username(String twitter_username) {
    this.twitter_username = twitter_username;
}

@Override
public String toString() {
    return "UserName: " + this.getUsername() + " Email: " + this.getEmail();
}

}

/*
 * put string into file jsonFileArr.json
 * [{"username":"Hello","email":"[email protected]","credits"
 * :"100","twitter_username":""},
 * {"username":"Goodbye","email":"[email protected]"
 * ,"credits":"0","twitter_username":""},
 * {"username":"mlsilva","email":"[email protected]"
 * ,"credits":"524","twitter_username":""},
 * {"username":"fsouza","email":"[email protected]"
 * ,"credits":"1052","twitter_username":""}]
 */

public class TestaGsonLista {

public static void main(String[] args) {
    Gson gson = new Gson();
    try {
        BufferedReader br = new BufferedReader(new FileReader(
                "C:\\Temp\\jsonFileArr.json"));
        JsonArray jsonArray = new JsonParser().parse(br).getAsJsonArray();
        for (int i = 0; i < jsonArray.size(); i++) {
            JsonElement str = jsonArray.get(i);
            Usuario obj = gson.fromJson(str, Usuario.class);
            System.out.println(obj);
            System.out.println(str);
            System.out.println("-------");
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

}

Console.log not working at all

I just had a same issue of none of my console message showing. It was simply because I was using the new Edge (Chromium based) browser on Windows 10. It does not show my console messages whereas Chrome does. I guessed it was an issue with Edge because I had another odd issue with Edge because it treated strings with single quotes and double quotes differently.

Nginx: Permission denied for nginx on Ubuntu

This works for me,

sudo chmod -R 777 /var/log/nginx

How to convert a byte array to a hex string in Java?

I found three different ways here: http://www.rgagnon.com/javadetails/java-0596.html

The most elegant one, as he also notes, I think is this one:

static final String HEXES = "0123456789ABCDEF";
public static String getHex( byte [] raw ) {
    if ( raw == null ) {
        return null;
    }
    final StringBuilder hex = new StringBuilder( 2 * raw.length );
    for ( final byte b : raw ) {
        hex.append(HEXES.charAt((b & 0xF0) >> 4))
            .append(HEXES.charAt((b & 0x0F)));
    }
    return hex.toString();
}

What is the difference between ndarray and array in numpy?

numpy.array is a function that returns a numpy.ndarray. There is no object type numpy.array.

Are complex expressions possible in ng-hide / ng-show?

Some of these above answers didn't work for me but this did. Just in case someone else has the same issue.

ng-show="column != 'vendorid' && column !='billingMonth'"

What is the difference between a JavaBean and a POJO?

In summary: similarities and differences are:

   java beans:                          Pojo:
-must extends serializable              -no need to extends or implement.
 or externalizable.                     
-must have public class .               - must have public class
-must have private instance variables.      -can have any access specifier variables.
-must have public setter and getter method. - may or may not have setter or getter method.
-must have no-arg constructor.           - can have constructor with agruments.

All JAVA Beans are POJO but not all POJOs are JAVA Beans.

Django - filtering on foreign key properties

This has been possible since the queryset-refactor branch landed pre-1.0. Ticket 4088 exposed the problem. This should work:

Asset.objects.filter(
    desc__contains=filter,
    project__name__contains="Foo").order_by("desc")

The Django Many-to-one documentation has this and other examples of following Foreign Keys using the Model API.

Code coverage with Mocha

Blanket.js works perfect too.

npm install --save-dev blanket

in front of your test/tests.js

require('blanket')({
    pattern: function (filename) {
        return !/node_modules/.test(filename);
    }
});

run mocha -R html-cov > coverage.html

Error when testing on iOS simulator: Couldn't register with the bootstrap server

Mike Ash posted a solution (god bless him!) that doesn't require a reboot. Just run:

launchctl list|grep UIKitApplication|awk '{print $3}'|xargs launchctl remove

The above command lists out all launchd jobs, searches for one with UIKitApplication in the name (which will be the job corresponding to your app that's improperly sticking around), extracts the name, and tells launchd to get rid of that job.

Ajax using https on an http page

Add the Access-Control-Allow-Origin header from the server

Access-Control-Allow-Origin: https://www.mysite.com

http://en.wikipedia.org/wiki/Cross-Origin_Resource_Sharing

Why is volatile needed in C?

I'll mention another scenario where volatiles are important.

Suppose you memory-map a file for faster I/O and that file can change behind the scenes (e.g. the file is not on your local hard drive, but is instead served over the network by another computer).

If you access the memory-mapped file's data through pointers to non-volatile objects (at the source code level), then the code generated by the compiler can fetch the same data multiple times without you being aware of it.

If that data happens to change, your program may become using two or more different versions of the data and get into an inconsistent state. This can lead not only to logically incorrect behavior of the program but also to exploitable security holes in it if it processes untrusted files or files from untrusted locations.

If you care about security, and you should, this is an important scenario to consider.

How do you convert between 12 hour time and 24 hour time in PHP?

// 24-hour time to 12-hour time 
$time_in_12_hour_format  = date("g:i a", strtotime("13:30"));

// 12-hour time to 24-hour time 
$time_in_24_hour_format  = date("H:i", strtotime("1:30 PM"));

Exponentiation in Python - should I prefer ** operator instead of math.pow and math.sqrt?

math.sqrt is the C implementation of square root and is therefore different from using the ** operator which implements Python's built-in pow function. Thus, using math.sqrt actually gives a different answer than using the ** operator and there is indeed a computational reason to prefer numpy or math module implementation over the built-in. Specifically the sqrt functions are probably implemented in the most efficient way possible whereas ** operates over a large number of bases and exponents and is probably unoptimized for the specific case of square root. On the other hand, the built-in pow function handles a few extra cases like "complex numbers, unbounded integer powers, and modular exponentiation".

See this Stack Overflow question for more information on the difference between ** and math.sqrt.

In terms of which is more "Pythonic", I think we need to discuss the very definition of that word. From the official Python glossary, it states that a piece of code or idea is Pythonic if it "closely follows the most common idioms of the Python language, rather than implementing code using concepts common to other languages." In every single other language I can think of, there is some math module with basic square root functions. However there are languages that lack a power operator like ** e.g. C++. So ** is probably more Pythonic, but whether or not it's objectively better depends on the use case.

What is the total amount of public IPv4 addresses?

According to Reserved IP addresses there are 588,514,304 reserved addresses and since there are 4,294,967,296 (2^32) IPv4 addressess in total, there are 3,706,452,992 public addresses.

And too many addresses in this post.

Allow a div to cover the whole page instead of the area within the container

Try this

#dimScreen {
    width: 100%;
    height: 100%;
    background:rgba(255,255,255,0.5);
    position: fixed;
    top: 0;
    left: 0;
}

How to save .xlsx data to file as a blob

Solution for me.

Step: 1

<a onclick="exportAsExcel()">Export to excel</a>

Step: 2

I'm using file-saver lib.

Read more: https://www.npmjs.com/package/file-saver

npm i file-saver

Step: 3

let FileSaver = require('file-saver'); // path to file-saver

function exportAsExcel() {
    let dataBlob = '...kAAAAFAAIcmtzaGVldHMvc2hlZXQxLnhtbFBLBQYAAAAACQAJAD8CAADdGAAAAAA='; // If have ; You should be split get blob data only
    this.downloadFile(dataBlob);
}

function downloadFile(blobContent){
    let blob = new Blob([base64toBlob(blobContent, 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet')], {});
    FileSaver.saveAs(blob, 'report.xlsx');
}

function base64toBlob(base64Data, contentType) {
    contentType = contentType || '';
    let sliceSize = 1024;
    let byteCharacters = atob(base64Data);
    let bytesLength = byteCharacters.length;
    let slicesCount = Math.ceil(bytesLength / sliceSize);
    let byteArrays = new Array(slicesCount);
    for (let sliceIndex = 0; sliceIndex < slicesCount; ++sliceIndex) {
        let begin = sliceIndex * sliceSize;
        let end = Math.min(begin + sliceSize, bytesLength);

        let bytes = new Array(end - begin);
        for (var offset = begin, i = 0; offset < end; ++i, ++offset) {
            bytes[i] = byteCharacters[offset].charCodeAt(0);
        }
        byteArrays[sliceIndex] = new Uint8Array(bytes);
    }
    return new Blob(byteArrays, { type: contentType });
}

Work for me. ^^

Getting a list of all subdirectories in the current directory

This function, with a given parent directory iterates over all its directories recursively and prints all the filenames which it founds inside. Too useful.

import os

def printDirectoryFiles(directory):
   for filename in os.listdir(directory):  
        full_path=os.path.join(directory, filename)
        if not os.path.isdir(full_path): 
            print( full_path + "\n")


def checkFolders(directory):

    dir_list = next(os.walk(directory))[1]

    #print(dir_list)

    for dir in dir_list:           
        print(dir)
        checkFolders(directory +"/"+ dir) 

    printDirectoryFiles(directory)       

main_dir="C:/Users/S0082448/Desktop/carpeta1"

checkFolders(main_dir)


input("Press enter to exit ;")

Control the dashed border stroke length and distance between strokes

In addition to the border-image property, there are a few other ways to create a dashed border with control over the length of the stroke and the distance between them. They are described below:

Method 1: Using SVG

We can create the dashed border by using a path or a polygon element and setting the stroke-dasharray property. The property takes two parameters where one defines the size of the dash and the other determines the space between them.

Pros:

  1. SVGs by nature are scalable graphics and can adapt to any container dimensions.
  2. Can work very well even if there is a border-radius involved. We would just have replace the path with a circle like in this answer (or) convert the path into a circle.
  3. Browser support for SVG is pretty good and fallback can be provided using VML for IE8-.

Cons:

  1. When the dimensions of the container do not change proportionately, the paths tend to scale resulting in a change in size of the dash and the space between them (try hovering on the first box in the snippet). This can be controlled by adding vector-effect='non-scaling-stroke' (as in the second box) but the browser support for this property is nil in IE.

_x000D_
_x000D_
.dashed-vector {_x000D_
  position: relative;_x000D_
  height: 100px;_x000D_
  width: 300px;_x000D_
}_x000D_
svg {_x000D_
  position: absolute;_x000D_
  top: 0px;_x000D_
  left: 0px;_x000D_
  height: 100%;_x000D_
  width: 100%;_x000D_
}_x000D_
path{_x000D_
  fill: none;_x000D_
  stroke: blue;_x000D_
  stroke-width: 5;_x000D_
  stroke-dasharray: 10, 10;_x000D_
}_x000D_
span {_x000D_
  position: absolute;_x000D_
  top: 0px;_x000D_
  left: 0px;_x000D_
  padding: 10px;_x000D_
}_x000D_
_x000D_
_x000D_
/* just for demo */_x000D_
_x000D_
div{_x000D_
  margin-bottom: 10px;_x000D_
  transition: all 1s;_x000D_
}_x000D_
div:hover{_x000D_
  height: 100px;_x000D_
  width: 400px;_x000D_
}
_x000D_
<div class='dashed-vector'>_x000D_
  <svg viewBox='0 0 300 100' preserveAspectRatio='none'>_x000D_
    <path d='M0,0 300,0 300,100 0,100z' />_x000D_
  </svg>_x000D_
  <span>Some content</span>_x000D_
</div>_x000D_
_x000D_
<div class='dashed-vector'>_x000D_
  <svg viewBox='0 0 300 100' preserveAspectRatio='none'>_x000D_
    <path d='M0,0 300,0 300,100 0,100z' vector-effect='non-scaling-stroke'/>_x000D_
  </svg>_x000D_
  <span>Some content</span>_x000D_
</div>
_x000D_
_x000D_
_x000D_


Method 2: Using Gradients

We can use multiple linear-gradient background images and position them appropriately to create a dashed border effect. This can also be done with a repeating-linear-gradient but there is not much improvement because of using a repeating gradient as we need each gradient to repeat in only one direction.

_x000D_
_x000D_
.dashed-gradient{_x000D_
  height: 100px;_x000D_
  width: 200px;_x000D_
  padding: 10px;_x000D_
  background-image: linear-gradient(to right, blue 50%, transparent 50%), linear-gradient(to right, blue 50%, transparent 50%), linear-gradient(to bottom, blue 50%, transparent 50%), linear-gradient(to bottom, blue 50%, transparent 50%);_x000D_
  background-position: left top, left bottom, left top, right top;_x000D_
  background-repeat: repeat-x, repeat-x, repeat-y, repeat-y;_x000D_
  background-size: 20px 3px, 20px 3px, 3px 20px, 3px 20px;_x000D_
}_x000D_
_x000D_
.dashed-repeating-gradient {_x000D_
  height: 100px;_x000D_
  width: 200px;_x000D_
  padding: 10px;_x000D_
  background-image: repeating-linear-gradient(to right, blue 0%, blue 50%, transparent 50%, transparent 100%), repeating-linear-gradient(to right, blue 0%, blue 50%, transparent 50%, transparent 100%), repeating-linear-gradient(to bottom, blue 0%, blue 50%, transparent 50%, transparent 100%), repeating-linear-gradient(to bottom, blue 0%, blue 50%, transparent 50%, transparent 100%);_x000D_
  background-position: left top, left bottom, left top, right top;_x000D_
  background-repeat: repeat-x, repeat-x, repeat-y, repeat-y;_x000D_
  background-size: 20px 3px, 20px 3px, 3px 20px, 3px 20px;_x000D_
}_x000D_
_x000D_
/* just for demo */_x000D_
_x000D_
div {_x000D_
  margin: 10px;_x000D_
  transition: all 1s;_x000D_
}_x000D_
div:hover {_x000D_
  height: 150px;_x000D_
  width: 300px;_x000D_
}
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/prefixfree/1.0.7/prefixfree.min.js"></script>_x000D_
<div class='dashed-gradient'>Some content</div>_x000D_
<div class='dashed-repeating-gradient'>Some content</div>
_x000D_
_x000D_
_x000D_

Pros:

  1. Scalable and can adapt even if the container's dimensions are dynamic.
  2. Does not make use of any extra pseudo-elements which means they can be kept aside for any other potential usage.

Cons:

  1. Browser support for linear gradients is comparatively lower and this is a no-go if you want to support IE 9-. Even libraries like CSS3 PIE do not support creation of gradient patterns in IE8-.
  2. Cannot be used when border-radius is involved because backgrounds don't curve based on border-radius. They get clipped instead.

Method 3: Box Shadows

We can create a small bar (in the shape of the dash) using pseudo-elements and then create multiple box-shadow versions of it to create a border like in the below snippet.

If the dash is a square shape then a single pseudo-element would be enough but if it is a rectangle, we would need one pseudo-element for the top + bottom borders and another for left + right borders. This is because the height and width for the dash on the top border will be different from that on the left.

Pros:

  1. The dimensions of the dash is controllable by changing the dimensions of the pseudo-element. The spacing is controllable by modifying the space between each shadow.
  2. A very unique effect can be produced by adding a different color for each box shadow.

Cons:

  1. Since we have to manually set the dimensions of the dash and the spacing, this approach is no good when the dimensions of the parent box is dynamic.
  2. IE8 and lower do not support box shadow. However, this can be overcome by using libraries like CSS3 PIE.
  3. Can be used with border-radius but positioning them would be very tricky with having to find points on a circle (and possibly even transform).

_x000D_
_x000D_
.dashed-box-shadow{_x000D_
  position: relative;_x000D_
  height: 120px;_x000D_
  width: 120px;_x000D_
  padding: 10px;_x000D_
}_x000D_
.dashed-box-shadow:before{ /* for border top and bottom */_x000D_
  position: absolute;_x000D_
  content: '';_x000D_
  top: 0px;_x000D_
  left: 0px;_x000D_
  height: 3px; /* height of the border top and bottom */_x000D_
  width: 10px; /* width of the border top and bottom */_x000D_
  background: blue; /* border color */_x000D_
  box-shadow: 20px 0px 0px blue, 40px 0px 0px blue, 60px 0px 0px blue, 80px 0px 0px blue, 100px 0px 0px blue, /* top border */_x000D_
    0px 110px 0px blue, 20px 110px 0px blue, 40px 110px 0px blue, 60px 110px 0px blue, 80px 110px 0px blue, 100px 110px 0px blue; /* bottom border */_x000D_
}_x000D_
.dashed-box-shadow:after{ /* for border left and right */_x000D_
  position: absolute;_x000D_
  content: '';_x000D_
  top: 0px;_x000D_
  left: 0px;_x000D_
  height: 10px; /* height of the border left and right */_x000D_
  width: 3px; /* width of the border left and right */_x000D_
  background: blue; /* border color */_x000D_
  box-shadow: 0px 20px 0px blue, 0px 40px 0px blue, 0px 60px 0px blue, 0px 80px 0px blue, 0px 100px 0px blue, /* left border */_x000D_
    110px 0px 0px blue, 110px 20px 0px blue, 110px 40px 0px blue, 110px 60px 0px blue, 110px 80px 0px blue, 110px 100px 0px blue; /* right border */_x000D_
}
_x000D_
<div class='dashed-box-shadow'>Some content</div>
_x000D_
_x000D_
_x000D_

How to get terminal's Character Encoding

locale command with no arguments will print the values of all of the relevant environment variables except for LANGUAGE.

For current encoding:

locale charmap

For available locales:

locale -a

For available encodings:

locale -m

illegal use of break statement; javascript

You need to make sure requestAnimFrame stops being called once game == 1. A break statement only exits a traditional loop (e.g. while()).

function loop() {
    if (isPlaying) {
        jet1.draw();
        drawAllEnemies();
        if (game != 1) {
            requestAnimFrame(loop);
        }
    }
}

Or alternatively you could simply skip the second if condition and change the first condition to if (isPlaying && game !== 1). You would have to make a variable called game and give it a value of 0. Add 1 to it every game.

How to center the elements in ConstraintLayout

just add

android:gravity="center"

and done :)

SQL query to find third highest salary in company

The SQL-Server implementation of this will be:

SELECT SALARY FROM EMPLOYEES OFFSET 2 ROWS FETCH NEXT 1 ROWS ONLY

Model Binding to a List MVC 4

~Controller

namespace ListBindingTest.Controllers
{
    public class HomeController : Controller
    {
        //
        // GET: /Home/

        public ActionResult Index()
        {
            List<String> tmp = new List<String>();
            tmp.Add("one");
            tmp.Add("two");
            tmp.Add("Three");
            return View(tmp);
        }

        [HttpPost]
        public ActionResult Send(IList<String> input)
        {
            return View(input);
        }    
    }
}

~ Strongly Typed Index View

@model IList<String>

@{
    Layout = null;
}

<!DOCTYPE html>

<html>
<head>
<meta name="viewport" content="width=device-width" />
<title>Index</title>
</head>
<body>
    <div>
    @using(Html.BeginForm("Send", "Home", "POST"))
    {
        @Html.EditorFor(x => x)
        <br />
        <input type="submit" value="Send" />
    }
    </div>
</body>
</html>

~ Strongly Typed Send View

@model IList<String>

@{
    Layout = null;
}

<!DOCTYPE html>

<html>
<head>
<meta name="viewport" content="width=device-width" />
<title>Send</title>
</head>
<body>
    <div>
    @foreach(var element in @Model)
    {
        @element
        <br />
    }
    </div>
</body>
</html>

This is all that you had to do man, change his MyViewModel model to IList.

Check if all values of array are equal

You can use Array.every if supported:

var equals = array.every(function(value, index, array){
    return value === array[0];
});

Alternatives approach of a loop could be something like sort

var temp = array.slice(0).sort();
var equals = temp[0] === temp[temp.length - 1];

Or, if the items are like the question, something dirty like:

var equals = array.join('').split(array[0]).join('').length === 0;

Also works.

ValueError: unconverted data remains: 02:05

You have to parse all of the input string, you cannot just ignore parts.

from datetime import date, datetime

for item in j:
    st = datetime.strptime(item['start'], '%A %d %B %H:%M')

    if st.date() == date.today():
        item['start'] = st.time()

Here, we compare the date to today's date by using more datetime objects instead of trying to use strings.

The alternative is to only pass in part of the item['start'] string (splitting out just the time), but there really is no point here, not when you could just parse everything in one step first.

Xcode - Warning: Implicit declaration of function is invalid in C99

should call the function properly; like- Fibonacci:input

How do I compare 2 rows from the same table (SQL Server)?

OK, after 2 years it's finally time to correct the syntax:

SELECT  t1.value, t2.value
FROM    MyTable t1
JOIN    MyTable t2
ON      t1.id = t2.id
WHERE   t1.id = @id
        AND t1.status = @status1
        AND t2.status = @status2

How do I find the current machine's full hostname in C (hostname and domain information)?

I believe you are looking for:

gethostbyaddress

Just pass it the localhost IP.

There is also a gethostbyname function, that is also usefull.

Java foreach loop: for (Integer i : list) { ... }

One way to do that is to use a counter:

ArrayList<Integer> list = new ArrayList<Integer>();
...
int size = list.size();
for (Integer i : list) { 
    ...
    if (--size == 0) {
        // Last item.
        ...
    }
}

Edit

Anyway, as Tom Hawtin said, it is sometimes better to use the "old" syntax when you need to get the current index information, by using a for loop or the iterator, as everything you win when using the Java5 syntax will be lost in the loop itself...

for (int i = 0; i < list.size(); i++) {
    ...

    if (i == (list.size() - 1)) {
        // Last item...
    }
}

or

for (Iterator it = list.iterator(); it.hasNext(); ) {
    ...

    if (!it.hasNext()) {
        // Last item...
    }
}

How do I create an Excel chart that pulls data from multiple sheets?

Use the Chart Wizard.

On Step 2 of 4, there is a tab labeled "Series". There are 3 fields and a list box on this tab. The list box shows the different series you are already including on the chart. Each series has both a "Name" field and a "Values" field that is specific to that series. The final field is the "Category (X) axis labels" field, which is common to all series.

Click on the "Add" button below the list box. This will add a blank series to your list box. Notice that the values for "Name" and for "Values" change when you highlight a series in the list box.

Select your new series.

There is an icon in each field on the right side. This icon allows you to select cells in the workbook to pull the data from. When you click it, the Wizard temporarily hides itself (except for the field you are working in) allowing you to interact with the workbook.

Select the appropriate sheet in the workbook and then select the fields with the data you want to show in the chart. The button on the right of the field can be clicked to unhide the wizard.

Hope that helps.

EDIT: The above applies to 2003 and before. For 2007, when the chart is selected, you should be able to do a similar action using the "Select Data" option on the "Design" tab of the ribbon. This opens up a dialog box listing the Series for the chart. You can select the series just as you could in Excel 2003, but you must use the "Add" and "Edit" buttons to define custom series.

batch file to copy files to another location?

@echo off
xcopy ...

Replace ... with the appropriate xcopy arguments to copy what you want copied.

Clear Cache in Android Application programmatically

The answer from dhams is correct (after having been edited several times), but as the many edits of the code shows, it is difficult to write correct and robust code for deleting a directory (with sub-dirs) yourself. So I strongly suggest using Apache Commons IO, or some other API that does this for you:

import org.apache.commons.io.FileUtils;

...

// Delete local cache dir (ignoring any errors):
FileUtils.deleteQuietly(context.getCacheDir());

PS: Also delete the directory returned by context.getExternalCacheDir() if you use that.

To be able to use Apache Commons IO, add this to your build.gradle file, in the dependencies part:

compile 'commons-io:commons-io:2.4'

Recursively find files with a specific extension

As an alternative to using -regex option on find, since the question is labeled , you can use the brace expansion mechanism:

eval find . -false "-o -name Robert".{jpg,pdf}

What is the difference between a static and a non-static initialization code block

This is directly from http://www.programcreek.com/2011/10/java-class-instance-initializers/

1. Execution Order

Look at the following class, do you know which one gets executed first?

public class Foo {
 
    //instance variable initializer
    String s = "abc";
 
    //constructor
    public Foo() {
        System.out.println("constructor called");
    }
 
    //static initializer
    static {
        System.out.println("static initializer called");
    }
 
    //instance initializer
    {
        System.out.println("instance initializer called");
    }
 
    public static void main(String[] args) {
        new Foo();
        new Foo();
    }
}

Output:

static initializer called

instance initializer called

constructor called

instance initializer called

constructor called

2. How do Java instance initializer work?

The instance initializer above contains a println statement. To understand how it works, we can treat it as a variable assignment statement, e.g., b = 0. This can make it more obvious to understand.

Instead of

int b = 0, you could write

int b;
b = 0;

Therefore, instance initializers and instance variable initializers are pretty much the same.

3. When are instance initializers useful?

The use of instance initializers are rare, but still it can be a useful alternative to instance variable initializers if:

  1. Initializer code must handle exceptions
  2. Perform calculations that can’t be expressed with an instance variable initializer.

Of course, such code could be written in constructors. But if a class had multiple constructors, you would have to repeat the code in each constructor.

With an instance initializer, you can just write the code once, and it will be executed no matter what constructor is used to create the object. (I guess this is just a concept, and it is not used often.)

Another case in which instance initializers are useful is anonymous inner classes, which can’t declare any constructors at all. (Will this be a good place to place a logging function?)

Thanks to Derhein.

Also note that Anonymous classes that implement interfaces [1] have no constructors. Therefore instance initializers are needed to execute any kinds of expressions at construction time.

How can I convert a PFX certificate file for use with Apache on a linux server?

SSLSHopper has some pretty thorough articles about moving between different servers.

http://www.sslshopper.com/how-to-move-or-copy-an-ssl-certificate-from-one-server-to-another.html

Just pick the relevant link at bottom of this page.

Note: they have an online converter which gives them access to your private key. They can probably be trusted but it would be better to use the OPENSSL command (also shown on this site) to keep the private key private on your own machine.

Clearing a text field on button click

If you want to reset it, then simple use:

<input type="reset" value="Reset" />

But beware, it will not clear out textboxes that have default value. For example, if we have the following textboxes and by default, they have the following values:

<input id="textfield1" type="text" value="sample value 1" />
<input id="textfield2" type="text" value="sample value 2" />

So, to clear it out, compliment it with javascript:

function clearText()  
{
    document.getElementById('textfield1').value = "";
    document.getElementById('textfield2').value = "";
}  

And attach it to onclick of the reset button:
<input type="reset" value="Reset" onclick="clearText()" />

Rails: call another controller action from a controller

To use one controller from another, do this:

def action_that_calls_one_from_another_controller
  controller_you_want = ControllerYouWant.new
  controller_you_want.request = request
  controller_you_want.response = response
  controller_you_want.action_you_want
end

Oracle - Insert New Row with Auto Incremental ID

This is a simple way to do it without any triggers or sequences:

insert into WORKQUEUE (ID, facilitycode, workaction, description) values ((select count(1)+1 from WORKQUEUE), 'J', 'II', 'TESTVALUES');

Note : here need to use count(1) in place of max(id) column

It perfectly works for an empty table also.

How can I find the location of origin/master in git, and how do I change it?

I was wondering the same thing about my repo. In my case I had an old remote that I wasn't pushing to anymore so I needed to remove it.

Get list of remotes:

git remote

Remove the one that you don't need

git remote rm {insert remote to remove}

CSS - Make divs align horizontally

you can use the clip property:

#container {
  position: absolute;
  clip: rect(0px,200px,100px,0px);
  overflow: hidden;
  background: red;
}

note the position: absolute and overflow: hidden needed in order to get clip to work.

How to update multiple columns in single update statement in DB2

If the values came from another table, you might want to use

 UPDATE table1 t1 
 SET (col1, col2) = (
      SELECT col3, col4 
      FROM  table2 t2 
      WHERE t1.col8=t2.col9
 )

Example:

UPDATE table1
SET (col1, col2, col3) =(
   (SELECT MIN (ship_charge), MAX (ship_charge) FROM orders), 
   '07/01/2007'
)
WHERE col4 = 1001;

What is the difference between json.dumps and json.load?

dumps takes an object and produces a string:

>>> a = {'foo': 3}
>>> json.dumps(a)
'{"foo": 3}'

load would take a file-like object, read the data from that object, and use that string to create an object:

with open('file.json') as fh:
    a = json.load(fh)

Note that dump and load convert between files and objects, while dumps and loads convert between strings and objects. You can think of the s-less functions as wrappers around the s functions:

def dump(obj, fh):
    fh.write(dumps(obj))

def load(fh):
    return loads(fh.read())

How to achieve function overloading in C?

As already stated, overloading in the sense that you mean isn't supported by C. A common idiom to solve the problem is making the function accept a tagged union. This is implemented by a struct parameter, where the struct itself consists of some sort of type indicator, such as an enum, and a union of the different types of values. Example:

#include <stdio.h>

typedef enum {
    T_INT,
    T_FLOAT,
    T_CHAR,
} my_type;

typedef struct {
    my_type type;
    union {
        int a; 
        float b; 
        char c;
    } my_union;
} my_struct;

void set_overload (my_struct *whatever) 
{
    switch (whatever->type) 
    {
        case T_INT:
            whatever->my_union.a = 1;
            break;
        case T_FLOAT:
            whatever->my_union.b = 2.0;
            break;
        case T_CHAR:
            whatever->my_union.c = '3';
    }
}

void printf_overload (my_struct *whatever) {
    switch (whatever->type) 
    {
        case T_INT:
            printf("%d\n", whatever->my_union.a);
            break;
        case T_FLOAT:
            printf("%f\n", whatever->my_union.b);
            break;
        case T_CHAR:
            printf("%c\n", whatever->my_union.c);
            break;
    }

}

int main (int argc, char* argv[])
{
    my_struct s;

    s.type=T_INT;
    set_overload(&s);
    printf_overload(&s);

    s.type=T_FLOAT;
    set_overload(&s);
    printf_overload(&s);

    s.type=T_CHAR;
    set_overload(&s);
    printf_overload(&s); 
}

PHP returning JSON to JQUERY AJAX CALL

You can return json in PHP this way:

header('Content-Type: application/json');
echo json_encode(array('foo' => 'bar'));
exit;

Can the "IN" operator use LIKE-wildcards (%) in Oracle?

It seems that you can use regexp too

WHERE NOT REGEXP_LIKE(field, '^Done|^Finished')

I'm not sure how well this will perform though ... see here

SQL Count for each date

Select count(created_date) total
     , created_dt
  from table
group by created_date
order by created_date desc

const to Non-const Conversion in C++

void SomeClass::changeASettingAndCallAFunction() const {
    someSetting = 0; //Can't do this
    someFunctionThatUsesTheSetting();
}

Another solution is to call said function in-between making edits to variables that the const function uses. This idea was what solved my problem being as I was not inclined to change the signature of the function and had to use the "changeASettingAndCallAFunction" method as a mediator:

When you call the function you can first make edits to the setting before the call, or (if you aren't inclined to mess with the invoking place) perhaps call the function where you need the change to the variable to be propagated (like in my case).

void SomeClass::someFunctionThatUsesTheSetting() const {
     //We really don't want to touch this functions implementation
     ClassUsesSetting* classUsesSetting = ClassUsesSetting::PropagateAcrossClass(someSetting);
     /*
         Do important stuff
     */
}

void SomeClass::changeASettingAndCallAFunction() const {
     someFunctionThatUsesTheSetting();
     /*
         Have to do this
     */
}

void SomeClass::nonConstInvoker(){
    someSetting = 0;
    changeASettingAndCallAFunction();
}

Now, when some reference to "someFunctionThatUsesTheSetting" is invoked, it will invoke with the change to someSetting.

Link entire table row?

I feel like the simplest solution is sans javascript and simply putting the link in each cell (provided you don't have massive gullies between your cells or really think border lines). Have your css:

.tableClass td a{
   display: block;
}

and then add a link per cell:

<table class="tableClass">
    <tr>
        <td><a href="#link">Link name</a></td>
        <td><a href="#link">Link description</a></td>
        <td><a href="#link">Link somthing else</a></td>
    </tr>
</table>

boring but clean.

How can I convert ArrayList<Object> to ArrayList<String>?

If you want to do it the dirty way, try this.

@SuppressWarnings("unchecked")
public ArrayList<String> convert(ArrayList<Object> a) {
   return (ArrayList) a;
}

Advantage: here you save time by not iterating over all objects.

Disadvantage: may produce a hole in your foot.

Node Sass couldn't find a binding for your current environment

If your terminal/command prompt says:

Node Sass could not find a binding 
for your current environment: 
OS X 64-bit with Node 0.10.x

and you have tried the following commands such as:

npm cache clean --force 
rm -rf node modules 
npm install 
npm rebuild node-sass 
npm rebuild node-sass

& still NOTHING works..

Just run this in the terminal manually:

node node_modules/node-sass/scripts/install.js

now run

npm start or yarn start