Programs & Examples On #C99

This tag is for questions regarding the International Standard ISO 9899:1999, aka "C99", with technical corrigenda, and for questions about code written in C99 (as opposed to K&R C, C89 or later C Standard revisions like the 2011 revision C11).

bool to int conversion

You tagged your question [C] and [C++] at the same time. The results will be consistent between the languages, but the structure of the the answer is different for each of these languages.

In C language your examples has no relation to bool whatsoever (that applies to C99 as well). In C language relational operators do not produce bool results. Both 4 > 5 and 4 < 5 are expressions that produce results of type int with values 0 or 1. So, there's no "bool to int conversion" of any kind taking place in your examples in C.

In C++ relational operators do indeed produce bool results. bool values are convertible to int type, with true converting to 1 and false converting to 0. This is guaranteed by the language.

P.S. C language also has a dedicated boolean type _Bool (macro-aliased as bool), and its integral conversion rules are essentially the same as in C++. But nevertheless this is not relevant to your specific examples in C. Once again, relational operators in C always produce int (not bool) results regardless of the version of the language specification.

What is the behavior of integer division?

Will result always be the floor of the division? What is the defined behavior?

Not quite. It rounds toward 0, rather than flooring.

6.5.5 Multiplicative operators

6 When integers are divided, the result of the / operator is the algebraic quotient with any fractional part discarded.88) If the quotient a/b is representable, the expression (a/b)*b + a%b shall equal a.

and the corresponding footnote:

  1. This is often called ‘‘truncation toward zero’’.

Of course two points to note are:

3 The usual arithmetic conversions are performed on the operands.

and:

5 The result of the / operator is the quotient from the division of the first operand by the second; the result of the % operator is the remainder. In both operations, if the value of the second operand is zero, the behavior is undefined.

[Note: Emphasis mine]

state machines tutorials

State machines are not something that inherently needs a tutorial to be explained or even used. What I suggest is that you take a look at the data and how it needs to be parsed.

For example, I had to parse the data protocol for a Near Space balloon flight computer, it stored data on the SD card in a specific format (binary) which needed to be parsed out into a comma seperated file. Using a state machine for this makes the most sense because depending on what the next bit of information is we need to change what we are parsing.

The code is written using C++, and is available as ParseFCU. As you can see, it first detects what version we are parsing, and from there it enters two different state machines.

It enters the state machine in a known-good state, at that point we start parsing and depending on what characters we encounter we either move on to the next state, or go back to a previous state. This basically allows the code to self-adapt to the way the data is stored and whether or not certain data exists at all even.

In my example, the GPS string is not a requirement for the flight computer to log, so processing of the GPS string may be skipped over if the ending bytes for that single log write is found.

State machines are simple to write, and in general I follow the rule that it should flow. Input going through the system should flow with certain ease from state to state.

Setting std=c99 flag in GCC

Instead of calling /usr/bin/gcc, use /usr/bin/c99. This is the Single-Unix-approved way of invoking a C99 compiler. On an Ubuntu system, this points to a script which invokes gcc after having added the -std=c99 flag, which is precisely what you want.

C99 stdint.h header and MS Visual Studio

Microsoft do not support C99 and haven't announced any plans to. I believe they intend to track C++ standards but consider C as effectively obsolete except as a subset of C++.

New projects in Visual Studio 2003 and later have the "Compile as C++ Code (/TP)" option set by default, so any .c files will be compiled as C++.

Printf long long int in C with GCC?

Try to update your compiler, I'm using GCC 4.7 on Windows 7 Starter x86 with MinGW and it compiles fine with the same options both in C99 and C11.

Printf width specifier to maintain precision of floating-point value

In one of my comments to an answer I lamented that I've long wanted some way to print all the significant digits in a floating point value in decimal form, in much the same way the as the question asks. Well I finally sat down and wrote it. It's not quite perfect, and this is demo code that prints additional information, but it mostly works for my tests. Please let me know if you (i.e. anyone) would like a copy of the whole wrapper program which drives it for testing.

static unsigned int
ilog10(uintmax_t v);

/*
 * Note:  As presented this demo code prints a whole line including information
 * about how the form was arrived with, as well as in certain cases a couple of
 * interesting details about the number, such as the number of decimal places,
 * and possibley the magnitude of the value and the number of significant
 * digits.
 */
void
print_decimal(double d)
{
        size_t sigdig;
        int dplaces;
        double flintmax;

        /*
         * If we really want to see a plain decimal presentation with all of
         * the possible significant digits of precision for a floating point
         * number, then we must calculate the correct number of decimal places
         * to show with "%.*f" as follows.
         *
         * This is in lieu of always using either full on scientific notation
         * with "%e" (where the presentation is always in decimal format so we
         * can directly print the maximum number of significant digits
         * supported by the representation, taking into acount the one digit
         * represented by by the leading digit)
         *
         *        printf("%1.*e", DBL_DECIMAL_DIG - 1, d)
         *
         * or using the built-in human-friendly formatting with "%g" (where a
         * '*' parameter is used as the number of significant digits to print
         * and so we can just print exactly the maximum number supported by the
         * representation)
         *
         *         printf("%.*g", DBL_DECIMAL_DIG, d)
         *
         *
         * N.B.:  If we want the printed result to again survive a round-trip
         * conversion to binary and back, and to be rounded to a human-friendly
         * number, then we can only print DBL_DIG significant digits (instead
         * of the larger DBL_DECIMAL_DIG digits).
         *
         * Note:  "flintmax" here refers to the largest consecutive integer
         * that can be safely stored in a floating point variable without
         * losing precision.
         */
#ifdef PRINT_ROUND_TRIP_SAFE
# ifdef DBL_DIG
        sigdig = DBL_DIG;
# else
        sigdig = ilog10(uipow(FLT_RADIX, DBL_MANT_DIG - 1));
# endif
#else
# ifdef DBL_DECIMAL_DIG
        sigdig = DBL_DECIMAL_DIG;
# else
        sigdig = (size_t) lrint(ceil(DBL_MANT_DIG * log10((double) FLT_RADIX))) + 1;
# endif
#endif
        flintmax = pow((double) FLT_RADIX, (double) DBL_MANT_DIG); /* xxx use uipow() */
        if (d == 0.0) {
                printf("z = %.*s\n", (int) sigdig + 1, "0.000000000000000000000"); /* 21 */
        } else if (fabs(d) >= 0.1 &&
                   fabs(d) <= flintmax) {
                dplaces = (int) (sigdig - (size_t) lrint(ceil(log10(ceil(fabs(d))))));
                if (dplaces < 0) {
                        /* XXX this is likely never less than -1 */
                        /*
                         * XXX the last digit is not significant!!! XXX
                         *
                         * This should also be printed with sprintf() and edited...
                         */
                        printf("R = %.0f [%d too many significant digits!!!, zero decimal places]\n", d, abs(dplaces));
                } else if (dplaces == 0) {
                        /*
                         * The decimal fraction here is not significant and
                         * should always be zero  (XXX I've never seen this)
                         */
                        printf("R = %.0f [zero decimal places]\n", d);
                } else {
                        if (fabs(d) == 1.0) {
                                /*
                                 * This is a special case where the calculation
                                 * is off by one because log10(1.0) is 0, but
                                 * we still have the leading '1' whole digit to
                                 * count as a significant digit.
                                 */
#if 0
                                printf("ceil(1.0) = %f, log10(ceil(1.0)) = %f, ceil(log10(ceil(1.0))) = %f\n",
                                       ceil(fabs(d)), log10(ceil(fabs(d))), ceil(log10(ceil(fabs(d)))));
#endif
                                dplaces--;
                        }
                        /* this is really the "useful" range of %f */
                        printf("r = %.*f [%d decimal places]\n", dplaces, d, dplaces);
                }
        } else {
                if (fabs(d) < 1.0) {
                        int lz;

                        lz = abs((int) lrint(floor(log10(fabs(d)))));
                        /* i.e. add # of leading zeros to the precision */
                        dplaces = (int) sigdig - 1 + lz;
                        printf("f = %.*f [%d decimal places]\n", dplaces, d, dplaces);
                } else {                /* d > flintmax */
                        size_t n;
                        size_t i;
                        char *df;

                        /*
                         * hmmmm...  the easy way to suppress the "invalid",
                         * i.e. non-significant digits is to do a string
                         * replacement of all dgits after the first
                         * DBL_DECIMAL_DIG to convert them to zeros, and to
                         * round the least significant digit.
                         */
                        df = malloc((size_t) 1);
                        n = (size_t) snprintf(df, (size_t) 1, "%.1f", d);
                        n++;                /* for the NUL */
                        df = realloc(df, n);
                        (void) snprintf(df, n, "%.1f", d);
                        if ((n - 2) > sigdig) {
                                /*
                                 * XXX rounding the integer part here is "hard"
                                 * -- we would have to convert the digits up to
                                 * this point back into a binary format and
                                 * round that value appropriately in order to
                                 * do it correctly.
                                 */
                                if (df[sigdig] >= '5' && df[sigdig] <= '9') {
                                        if (df[sigdig - 1] == '9') {
                                                /*
                                                 * xxx fixing this is left as
                                                 * an exercise to the reader!
                                                 */
                                                printf("F = *** failed to round integer part at the least significant digit!!! ***\n");
                                                free(df);
                                                return;
                                        } else {
                                                df[sigdig - 1]++;
                                        }
                                }
                                for (i = sigdig; df[i] != '.'; i++) {
                                        df[i] = '0';
                                }
                        } else {
                                i = n - 1; /* less the NUL */
                                if (isnan(d) || isinf(d)) {
                                        sigdig = 0; /* "nan" or "inf" */
                                }
                        }
                        printf("F = %.*s. [0 decimal places, %lu digits, %lu digits significant]\n",
                               (int) i, df, (unsigned long int) i, (unsigned long int) sigdig);
                        free(df);
                }
        }

        return;
}


static unsigned int
msb(uintmax_t v)
{
        unsigned int mb = 0;

        while (v >>= 1) { /* unroll for more speed...  (see ilog2()) */
                mb++;
        }

        return mb;
}

static unsigned int
ilog10(uintmax_t v)
{
        unsigned int r;
        static unsigned long long int const PowersOf10[] =
                { 1LLU, 10LLU, 100LLU, 1000LLU, 10000LLU, 100000LLU, 1000000LLU,
                  10000000LLU, 100000000LLU, 1000000000LLU, 10000000000LLU,
                  100000000000LLU, 1000000000000LLU, 10000000000000LLU,
                  100000000000000LLU, 1000000000000000LLU, 10000000000000000LLU,
                  100000000000000000LLU, 1000000000000000000LLU,
                  10000000000000000000LLU };

        if (!v) {
                return ~0U;
        }
        /*
         * By the relationship "log10(v) = log2(v) / log2(10)", we need to
         * multiply "log2(v)" by "1 / log2(10)", which is approximately
         * 1233/4096, or (1233, followed by a right shift of 12).
         *
         * Finally, since the result is only an approximation that may be off
         * by one, the exact value is found by subtracting "v < PowersOf10[r]"
         * from the result.
         */
        r = ((msb(v) * 1233) >> 12) + 1;

        return r - (v < PowersOf10[r]);
}

How to create a private class method?

Instance methods are defined inside a class definition block. Class methods are defined as singleton methods on the singleton class of a class, also informally known as the "metaclass" or "eigenclass". private is not a keyword, but a method (Module#private).

This is a call to method self#private/A#private which "toggles" private access on for all forthcoming instance method definitions until toggled otherwise:

class A
  private
    def instance_method_1; end
    def instance_method_2; end
    # .. and so forth
end

As noted earlier, class methods are really singleton methods defined on the singleton class.

def A.class_method; end

Or using a special syntax to open the definition body of the anonymous, singleton class of A:

class << A
  def class_method; end
end

The receiver of the "message private" - self - inside class A is the class object A. self inside the class << A block is another object, the singleton class.

The following example is in reality calling two different methods called private, using two different recipients or targets for the call. In the first part, we define a private instance method ("on class A"), in the latter we define a private class method (is in fact a singleton method on the singleton class object of A).

class A
  # self is A and private call "A.private()"
  private def instance_method; end

  class << self
    # self is A's singleton class and private call "A.singleton_class.private()"
    private def class_method; end
  end
end

Now, rewrite this example a bit:

class A
  private
    def self.class_method; end
end

Can you see the mistake [that Ruby language designers] made? You toggle on private access for all forthcoming instance methods of A, but proceed to declare a singleton method on a different class, the singleton class.

Using Ansible set_fact to create a dictionary from register results

Thank you Phil for your solution; in case someone ever gets in the same situation as me, here is a (more complex) variant:

---
# this is just to avoid a call to |default on each iteration
- set_fact:
    postconf_d: {}

- name: 'get postfix default configuration'
  command: 'postconf -d'
  register: command

# the answer of the command give a list of lines such as:
# "key = value" or "key =" when the value is null
- name: 'set postfix default configuration as fact'
  set_fact:
    postconf_d: >
      {{
        postconf_d |
        combine(
          dict([ item.partition('=')[::2]|map('trim') ])
        )
  with_items: command.stdout_lines

This will give the following output (stripped for the example):

"postconf_d": {
    "alias_database": "hash:/etc/aliases", 
    "alias_maps": "hash:/etc/aliases, nis:mail.aliases",
    "allow_min_user": "no", 
    "allow_percent_hack": "yes"
}

Going even further, parse the lists in the 'value':

- name: 'set postfix default configuration as fact'
  set_fact:
    postconf_d: >-
      {% set key, val = item.partition('=')[::2]|map('trim') -%}
      {% if ',' in val -%}
        {% set val = val.split(',')|map('trim')|list -%}
      {% endif -%}
      {{ postfix_default_main_cf | combine({key: val}) }}
  with_items: command.stdout_lines
...
"postconf_d": {
    "alias_database": "hash:/etc/aliases", 
    "alias_maps": [
        "hash:/etc/aliases", 
        "nis:mail.aliases"
    ], 
    "allow_min_user": "no", 
    "allow_percent_hack": "yes"
}

A few things to notice:

  • in this case it's needed to "trim" everything (using the >- in YAML and -%} in Jinja), otherwise you'll get an error like:

    FAILED! => {"failed": true, "msg": "|combine expects dictionaries, got u\"  {u'...
    
  • obviously the {% if .. is far from bullet-proof

  • in the postfix case, val.split(',')|map('trim')|list could have been simplified to val.split(', '), but I wanted to point out the fact you will need to |list otherwise you'll get an error like:

    "|combine expects dictionaries, got u\"{u'...': <generator object do_map at ...
    

Hope this can help.

Uninstalling an MSI file from the command line without using msiexec

I would try the following syntax - it works for me.

msiexec /x filename.msi /q 

Running python script inside ipython

from within the directory of "my_script.py" you can simply do:

%run ./my_script.py

Delete duplicate records from a SQL table without a primary key

select t1.* from employee t1, employee t2 where t1.empid=t2.empid and t1.empname = t2.empname and t1.salary = t2.salary
group by t1.empid, t1.empname,t1.salary having count(*) > 1

Why do we have to override the equals() method in Java?

By default .equals() uses == identity function to compare which obviously doesn't work as the instances test1 and test2 are not the same. == only works with primitive data types like int or string. So you need to override it to make it work by comparing all the member variables of the Test class

How can I set multiple CSS styles in JavaScript?

You can write a function that will set declarations individually in order not to overwrite any existing declarations that you don't supply. Let's say you have this object parameter list of declarations:

const myStyles = {
  'background-color': 'magenta',
  'border': '10px dotted cyan',
  'border-radius': '5px',
  'box-sizing': 'border-box',
  'color': 'yellow',
  'display': 'inline-block',
  'font-family': 'monospace',
  'font-size': '20px',
  'margin': '1em',
  'padding': '1em'
};

You might write a function that looks like this:

function applyStyles (el, styles) {
  for (const prop in styles) {
    el.style.setProperty(prop, styles[prop]);
  }
};

which takes an element and an object property list of style declarations to apply to that object. Here's a usage example:

const p = document.createElement('p');
p.textContent = 'This is a paragraph.';
document.body.appendChild(p);

applyStyles(p, myStyles);
applyStyles(document.body, {'background-color': 'grey'});

_x000D_
_x000D_
// styles to apply_x000D_
const myStyles = {_x000D_
  'background-color': 'magenta',_x000D_
  'border': '10px dotted cyan',_x000D_
  'border-radius': '5px',_x000D_
  'box-sizing': 'border-box',_x000D_
  'color': 'yellow',_x000D_
  'display': 'inline-block',_x000D_
  'font-family': 'monospace',_x000D_
  'font-size': '20px',_x000D_
  'margin': '1em',_x000D_
  'padding': '1em'_x000D_
};_x000D_
_x000D_
function applyStyles (el, styles) {_x000D_
  for (const prop in styles) {_x000D_
    el.style.setProperty(prop, styles[prop]);_x000D_
  }_x000D_
};_x000D_
_x000D_
// create example paragraph and append it to the page body_x000D_
const p = document.createElement('p');_x000D_
p.textContent = 'This is a paragraph.';_x000D_
document.body.appendChild(p);_x000D_
_x000D_
// when the paragraph is clicked, call the function, providing the_x000D_
// paragraph and myStyles object as arguments_x000D_
p.onclick = (ev) => {_x000D_
  applyStyles(p, myStyles);_x000D_
}_x000D_
_x000D_
// this time, target the page body and supply an object literal_x000D_
applyStyles(document.body, {'background-color': 'grey'});
_x000D_
_x000D_
_x000D_

How to search if dictionary value contains certain string with Python

import re
for i in range(len(myDict.values())):
    for j in range(len(myDict.values()[i])):
         match=re.search(r'Mary', myDict.values()[i][j])
         if match:
                 print match.group() #Mary
                 print myDict.keys()[i] #firstName
                 print myDict.values()[i][j] #Mary-Ann

jQuery .slideRight effect

If you're willing to include the jQuery UI library, in addition to jQuery itself, then you can simply use hide(), with additional arguments, as follows:

$(document).ready(
    function(){
        $('#slider').click(
            function(){
                $(this).hide('slide',{direction:'right'},1000);

            });
    });

JS Fiddle demo.


Without using jQuery UI, you could achieve your aim just using animate():

$(document).ready(
    function(){
        $('#slider').click(
            function(){
                $(this)
                    .animate(
                        {
                            'margin-left':'1000px'
                            // to move it towards the right and, probably, off-screen.
                        },1000,
                        function(){
                            $(this).slideUp('fast');
                            // once it's finished moving to the right, just 
                            // removes the the element from the display, you could use
                            // `remove()` instead, or whatever.
                        }
                        );

            });
    });

JS Fiddle demo

If you do choose to use jQuery UI, then I'd recommend linking to the Google-hosted code, at: https://ajax.googleapis.com/ajax/libs/jqueryui/1.8.6/jquery-ui.min.js

How can I force input to uppercase in an ASP.NET textbox?

CSS could be of help here.

style="text-transform: uppercase";"

does this help?

Excel Calculate the date difference from today from a cell of "7/6/2012 10:26:42"

You can use the datedif function to find out difference in days.

=DATEDIF(A1,TODAY(),"d")

Quote from excel.datedif.com

The mysterious datedif function in Microsoft Excel

The Datedif function is used to calculate interval between two dates in days, months or years.

This function is available in all versions of Excel but is not documented. It is not even listed in the "Insert Function" dialog box. Hence it must be typed manually in the formula box. Syntax

DATEDIF( start_date, end_date, interval_unit )

start_date from date end_date to date (must be after start_date) interval_unit Unit to be used for output interval Values for interval_unit

interval_unit Description

D Number of days

M Number of complete months

Y Number of complete years

YD Number of days excluding years

MD Number of days excluding months and years

YM Number of months excluding years

Errors

Error Description

#NUM! The end_date is later than (greater than) the start_date or interval_unit has an invalid value. #VALUE! end_date or start_date is invalid.

File path issues in R using Windows ("Hex digits in character string" error)

Replacing backslash with forward slash worked for me on Windows.

How do I delete an entity from symfony2

DELETE FROM ... WHERE id=...;

protected function templateRemove($id){
            $em = $this->getDoctrine()->getManager();
            $entity = $em->getRepository('XXXBundle:Templates')->findOneBy(array('id' => $id));

            if ($entity != null){
                $em->remove($entity);
                $em->flush();
            }
        }

Node.js global proxy setting

You can try my package node-global-proxy which work with all node versions and most of http-client (axios, got, superagent, request etc.)

after install by

npm install node-global-proxy --save

a global proxy can start by

const proxy = require("node-global-proxy").default;

proxy.setConfig({
  http: "http://localhost:1080",
  https: "https://localhost:1080",
});
proxy.start();

/** Proxy working now! */

More information available here: https://github.com/wwwzbwcom/node-global-proxy

Differences between Microsoft .NET 4.0 full Framework and Client Profile

What's new in .NET Framework 4 Client Profile RTM explains many of the differences:

When to use NET4 Client Profile and when to use NET4 Full Framework?
NET4 Client Profile:
Always target NET4 Client Profile for all your client desktop applications (including Windows Forms and WPF apps).

NET4 Full framework:
Target NET4 Full only if the features or assemblies that your app need are not included in the Client Profile. This includes:

  • If you are building Server apps. Such as:
    o ASP.Net apps
    o Server-side ASMX based web services
  • If you use legacy client scenarios. Such as:
    o Use System.Data.OracleClient.dll which is deprecated in NET4 and not included in the Client Profile.
    o Use legacy Windows Workflow Foundation 3.0 or 3.5 (WF3.0 , WF3.5)
  • If you targeting developer scenarios and need tool such as MSBuild or need access to design assemblies such as System.Design.dll

However, as stated on MSDN, this is not relevant for >=4.5:

Starting with the .NET Framework 4.5, the Client Profile has been discontinued and only the full redistributable package is available. Optimizations provided by the .NET Framework 4.5, such as smaller download size and faster deployment, have eliminated the need for a separate deployment package. The single redistributable streamlines the installation process and simplifies your app's deployment options.

Android replace the current fragment with another fragment

it's very simple how to replace with Fragment.

DataFromDb changeActivity = new DataFromDb();
    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
    transaction.replace(R.id.changeFrg, changeActivity);
    transaction.commit();

Should I size a textarea with CSS width / height or HTML cols / rows attributes?

A major feature of textareas is that they are expandable. On a web page this can result in scroll bars appearing on the text area if the text length overfills the space you set (be that using rows, or be that using CSS. That can be a problem when a user decides to print, particularly with 'printing' to PDF - so set a comfortably large min-height for printed textareas with a conditional CSS rule:

@media print { 
textarea {
min-height: 900px;  
}
}

Defining a variable with or without export

As you might already know, UNIX allows processes to have a set of environment variables, which are key/value pairs, both key and value being strings. Operating system is responsible for keeping these pairs for each process separately.

Program can access its environment variables through this UNIX API:

  • char *getenv(const char *name);
  • int setenv(const char *name, const char *value, int override);
  • int unsetenv(const char *name);

Processes also inherit environment variables from parent processes. Operating system is responsible for creating a copy of all "envars" at the moment the child process is created.

Bash, among other shells, is capable of setting its environment variables on user request. This is what export exists for.

export is a Bash command to set environment variable for Bash. All variables set with this command would be inherited by all processes that this Bash would create.

More on Environment in Bash

Another kind of variable in Bash is internal variable. Since Bash is not just interactive shell, it is in fact a script interpreter, as any other interpreter (e.g. Python) it is capable of keeping its own set of variables. It should be mentioned that Bash (unlike Python) supports only string variables.

Notation for defining Bash variables is name=value. These variables stay inside Bash and have nothing to do with environment variables kept by operating system.

More on Shell Parameters (including variables)

Also worth noting that, according to Bash reference manual:

The environment for any simple command or function may be augmented temporarily by prefixing it with parameter assignments, as described in Shell Parameters. These assignment statements affect only the environment seen by that command.


To sum things up:

  • export is used to set environment variable in operating system. This variable will be available to all child processes created by current Bash process ever after.
  • Bash variable notation (name=value) is used to set local variables available only to current process of bash
  • Bash variable notation prefixing another command creates environment variable only for scope of that command.

Count distinct value pairs in multiple columns in SQL

Having to return the count of a unique Bill of Materials (BOM) where each BOM have multiple positions, I dd something like this:

select t_item, t_pono, count(distinct ltrim(rtrim(t_item)) + cast(t_pono as varchar(3))) as [BOM Pono Count]
from BOMMaster
where t_pono = 1
group by t_item, t_pono

Given t_pono is a smallint datatype and t_item is a varchar(16) datatype

Calling one method from another within same class in Python

To call the method, you need to qualify function with self.. In addition to that, if you want to pass a filename, add a filename parameter (or other name you want).

class MyHandler(FileSystemEventHandler):

    def on_any_event(self, event):
        srcpath = event.src_path
        print (srcpath, 'has been ',event.event_type)
        print (datetime.datetime.now())
        filename = srcpath[12:]
        self.dropbox_fn(filename) # <----

    def dropbox_fn(self, filename):  # <-----
        print('In dropbox_fn:', filename)

How to create a new file in unix?

Try > workdirectory/filename.txt

This would:

  • truncate the file if it exists
  • create if it doesn't exist

You can consider it equivalent to:

rm -f workdirectory/filename.txt; touch workdirectory/filename.txt

How should I validate an e-mail address?

The key here is that you want to fully validate the email address. You don’t just want to check it for syntactic correctness, you want to check whether the email address is real.

Two obvious reasons: real users often mis-type their email addresses, and some users may put in fake email addresses. Therefore, you want to do a syntactic check and an existence check.

The best way to do this that I have found on Android is to use the free Cloudmersive Validation API for this.

The code looks like this:

ApiClient defaultClient = Configuration.getDefaultApiClient();

// Configure API key authorization: Apikey
ApiKeyAuth Apikey = (ApiKeyAuth) defaultClient.getAuthentication("Apikey");
Apikey.setApiKey("YOUR API KEY");

EmailApi apiInstance = new EmailApi();
String email = "email_example"; // String | Email address to validate, e.g. \"[email protected]\". The input is a string so be sure to enclose it in double-quotes.
try {
    FullEmailValidationResponse result = apiInstance.emailFullValidation(email);
    System.out.println(result);
} catch (ApiException e) {
    System.err.println("Exception when calling EmailApi#emailFullValidation");
    e.printStackTrace();
}

I’m using this in all my apps and it is great because I can validate the email addresses in the UX at the point of entry.

How to ignore deprecation warnings in Python

Not to beat you up about it but you are being warned that what you are doing will likely stop working when you next upgrade python. Convert to int and be done with it.

BTW. You can also write your own warnings handler. Just assign a function that does nothing. How to redirect python warnings to a custom stream?

Best way to check for IE less than 9 in JavaScript without library

for what it's worth:

    if(  document.addEventListener  ){
        alert("you got IE9 or greater");
    }

This successfully targets IE 9+ because the addEventListener method was supported very early on for every major browser but IE. (Chrome, Firefox, Opera, and Safari) MDN Reference. It is supported currently in IE9 and we can expect it to continue to be supported here on out.

how to convert a string to date in mysql?

Here's another two examples.

To output the day, month, and year, you can use:

select STR_TO_DATE('14/02/2015', '%d/%m/%Y');

Which produces:

2015-02-14

To also output the time, you can use:

select STR_TO_DATE('14/02/2017 23:38:12', '%d/%m/%Y %T');

Which produces:

2017-02-14 23:38:12

ALTER DATABASE failed because a lock could not be placed on database

In my scenario, there was no process blocking the database under sp_who2. However, we discovered because the database is much larger than our other databases that pending processes were still running which is why the database under the availability group still displayed as red/offline after we tried to 'resume data'by right clicking the paused database.

To check if you still have processes running just execute this command: select percent complete from sys.dm_exec_requests where percent_complete > 0

When does SQLiteOpenHelper onCreate() / onUpgrade() run?

Points to remember when extending SQLiteOpenHelper

  1. super(context, DBName, null, DBversion); - This should be invoked first line of constructor
  2. override onCreate and onUpgrade (if needed)
  3. onCreate will be invoked only when getWritableDatabase() or getReadableDatabase() is executed. And this will only invoked once when a DBName specified in the first step is not available. You can add create table query on onCreate method
  4. Whenever you want to add new table just change DBversion and do the queries in onUpgrade table or simply uninstall then install the app.

PostgreSQL - fetch the row which has the Max value for a column

I like the style of Mike Woodhouse's answer on the other page you mentioned. It's especially concise when the thing being maximised over is just a single column, in which case the subquery can just use MAX(some_col) and GROUP BY the other columns, but in your case you have a 2-part quantity to be maximised, you can still do so by using ORDER BY plus LIMIT 1 instead (as done by Quassnoi):

SELECT * 
FROM lives outer
WHERE (usr_id, time_stamp, trans_id) IN (
    SELECT usr_id, time_stamp, trans_id
    FROM lives sq
    WHERE sq.usr_id = outer.usr_id
    ORDER BY trans_id, time_stamp
    LIMIT 1
)

I find using the row-constructor syntax WHERE (a, b, c) IN (subquery) nice because it cuts down on the amount of verbiage needed.

How to get started with Windows 7 gadgets

Here's an excellent article by Scott Allen: Developing Gadgets for the Windows Sidebar

This site, Windows 7/Vista Sidebar Gadgets, has links to many gadget resources.

Assert equals between 2 Lists in Junit

For junit4! This question deserves a new answer written for junit5.

I realise this answer is written a couple years after the question, probably this feature wasn't around then. But now, it's easy to just do this:

@Test
public void test_array_pass()
{
  List<String> actual = Arrays.asList("fee", "fi", "foe");
  List<String> expected = Arrays.asList("fee", "fi", "foe");

  assertThat(actual, is(expected));
  assertThat(actual, is(not(expected)));
}

If you have a recent version of Junit installed with hamcrest, just add these imports:

import static org.junit.Assert.*;
import static org.hamcrest.CoreMatchers.*;

http://junit.org/junit4/javadoc/latest/org/junit/Assert.html#assertThat(T, org.hamcrest.Matcher)

http://junit.org/junit4/javadoc/latest/org/hamcrest/CoreMatchers.html

http://junit.org/junit4/javadoc/latest/org/hamcrest/core/Is.html

Is true == 1 and false == 0 in JavaScript?

Use === to equate the variables instead of ==.

== checks if the value of the variables is similar

=== checks if the value of the variables and the type of the variables are similar

Notice how

if(0===false) {
    document.write("oh!!! that's true");
}?

and

if(0==false) {
    document.write("oh!!! that's true");
}?

give different results

jQuery check if Cookie exists, if not create it

You can set the cookie after having checked if it exists with a value.

 $(document).ready(function(){            
      if ($.cookie('cookie')) { //if cookie isset
         //do stuff here like hide a popup when cookie isset
         //document.getElementById("hideElement").style.display = "none";
      }else{
         var CookieSet = $.cookie('cookie', 'value'); //set cookie
      }       
 });

How to get the correct range to set the value to a cell?

Solution : SpreadsheetApp.getActiveSheet().getRange('F2').setValue('hello')

Explanation :

Setting value in a cell in spreadsheet to which script is attached

SpreadsheetApp.getActiveSpreadsheet().getSheetByName(SHEET_NAME).getRange(RANGE).setValue(VALUE);

Setting value in a cell in sheet which is open currently and to which script is attached

SpreadsheetApp.getActiveSpreadsheet().getActiveSheet().getRange(RANGE).setValue(VALUE);

Setting value in a cell in some spreadsheet to which script is NOT attached (Destination sheet name known)

SpreadsheetApp.openById(SHEET_ID).getSheetByName(SHEET_NAME).getRange(RANGE).setValue(VALUE);

Setting value in a cell in some spreadsheet to which script is NOT attached (Destination sheet position known)

SpreadsheetApp.openById(SHEET_ID).getSheets()[POSITION].getRange(RANGE).setValue(VALUE);

These are constants, you must define them yourself

SHEET_ID

SHEET_NAME

POSITION

VALUE

RANGE

By script attached to a sheet I mean that script is residing in the script editor of that sheet. Not attached means not residing in the script editor of that sheet. It can be in any other place.

Oracle date format picture ends before converting entire input string

What you're trying to insert is not a date, I think, but a string. You need to use to_date() function, like this:

insert into table t1 (id, date_field) values (1, to_date('20.06.2013', 'dd.mm.yyyy'));

Simulate delayed and dropped packets on Linux

An easy to use network fault injection tool is Saboteur. It can simulate:

  • Total network partition
  • Remote service dead (not listening on the expected port)
  • Delays
  • Packet loss -TCP connection timeout (as often happens when two systems are separated by a stateful firewall)

Not Able To Debug App In Android Studio

What worked for me in Android Studio 3.2.1

Was:

RUN -> Attach debugger to Android Process --> com.my app

How to solve munmap_chunk(): invalid pointer error in C++

This happens when the pointer passed to free() is not valid or has been modified somehow. I don't really know the details here. The bottom line is that the pointer passed to free() must be the same as returned by malloc(), realloc() and their friends. It's not always easy to spot what the problem is for a novice in their own code or even deeper in a library. In my case, it was a simple case of an undefined (uninitialized) pointer related to branching.

The free() function frees the memory space pointed to by ptr, which must have been returned by a previous call to malloc(), calloc() or realloc(). Otherwise, or if free(ptr) has already been called before, undefined behavior occurs. If ptr is NULL, no operation is performed. GNU 2012-05-10 MALLOC(3)

char *words; // setting this to NULL would have prevented the issue

if (condition) {
    words = malloc( 512 );

    /* calling free sometime later works here */

    free(words)
} else {

    /* do not allocate words in this branch */
}

/* free(words);  -- error here --
*** glibc detected *** ./bin: munmap_chunk(): invalid pointer: 0xb________ ***/

There are many similar questions here about the related free() and rellocate() functions. Some notable answers providing more details:

*** glibc detected *** free(): invalid next size (normal): 0x0a03c978 ***
*** glibc detected *** sendip: free(): invalid next size (normal): 0x09da25e8 ***
glibc detected, realloc(): invalid pointer


IMHO running everything in a debugger (Valgrind) is not the best option because errors like this are often caused by inept or novice programmers. It's more productive to figure out the issue manually and learn how to avoid it in the future.

python NameError: name 'file' is not defined

file is not defined in Python3, which you are using apparently. The package you're instaling is not suitable for Python 3, instead, you should install Python 2.7 and try again.

See: http://docs.python.org/release/3.0/whatsnew/3.0.html#builtins

test if event handler is bound to an element in jQuery

With reference to SJG's answer and from W3Schools.com

As of jQuery version 1.7, the off() method is the new replacement for the unbind(), die() and undelegate() methods. This method brings a lot of consistency to the API, and we recommend that you use this method, as it simplifies the jQuery code base.

This gives:

$("#someid").off("click").live("click",function(){...

or

$("#someid").off("click").bind("click",function(){...

Manually adding a Userscript to Google Chrome

This parameter is is working for me:

--enable-easy-off-store-extension-install

Do the following:

  1. Right click on your "Chrome" icon.
  2. Choose properties
  3. At the end of your target line, place these parameters: --enable-easy-off-store-extension-install
  4. It should look like: chrome.exe --enable-easy-off-store-extension-install
  5. Start Chrome by double-clicking on the icon

Convert string to variable name in JavaScript

It can be done like this

_x000D_
_x000D_
(function(X, Y) {_x000D_
  _x000D_
  // X is the local name of the 'class'_x000D_
  // Doo is default value if param X is empty_x000D_
  var X = (typeof X == 'string') ? X: 'Doo';_x000D_
  var Y = (typeof Y == 'string') ? Y: 'doo';_x000D_
  _x000D_
  // this refers to the local X defined above_x000D_
  this[X] = function(doo) {_x000D_
    // object variable_x000D_
    this.doo = doo || 'doo it';_x000D_
  }_x000D_
  // prototypal inheritance for methods_x000D_
  // defined by another_x000D_
  this[X].prototype[Y] = function() {_x000D_
    return this.doo || 'doo';_x000D_
  };_x000D_
  _x000D_
  // make X global_x000D_
  window[X] = this[X];_x000D_
}('Dooa', 'dooa')); // give the names here_x000D_
_x000D_
// test_x000D_
doo = new Dooa('abc');_x000D_
doo2 = new Dooa('def');_x000D_
console.log(doo.dooa());_x000D_
console.log(doo2.dooa());
_x000D_
_x000D_
_x000D_

Way to read first few lines for pandas dataframe

I think you can use the nrows parameter. From the docs:

nrows : int, default None

    Number of rows of file to read. Useful for reading pieces of large files

which seems to work. Using one of the standard large test files (988504479 bytes, 5344499 lines):

In [1]: import pandas as pd

In [2]: time z = pd.read_csv("P00000001-ALL.csv", nrows=20)
CPU times: user 0.00 s, sys: 0.00 s, total: 0.00 s
Wall time: 0.00 s

In [3]: len(z)
Out[3]: 20

In [4]: time z = pd.read_csv("P00000001-ALL.csv")
CPU times: user 27.63 s, sys: 1.92 s, total: 29.55 s
Wall time: 30.23 s

Pandas index column title or name

You can just get/set the index via its name property

In [7]: df.index.name
Out[7]: 'Index Title'

In [8]: df.index.name = 'foo'

In [9]: df.index.name
Out[9]: 'foo'

In [10]: df
Out[10]: 
         Column 1
foo              
Apples          1
Oranges         2
Puppies         3
Ducks           4

Selenium IDE - Command to wait for 5 seconds

This will delay things for 5 seconds:

Command: pause
Target: 5000
Value:

This will delay things for 3 seconds:

Command: pause
Target: 3000
Value:

Documentation:

http://release.seleniumhq.org/selenium-core/1.0/reference.html#pause

enter image description here enter image description here

Visual studio code CSS indentation and formatting

I recommend using Prettier as it's very extensible but still works perfectly out of the box:

1. CMD + Shift + P -> Format Document

or

1. Select the text you want to Prettify
2. CMD + Shift + P -> Format Selection

Simple way to transpose columns and rows in SQL?

This normally requires you to know ALL the column AND row labels beforehand. As you can see in the query below, the labels are all listed in their entirely in both the UNPIVOT and the (re)PIVOT operations.

MS SQL Server 2012 Schema Setup:

create table tbl (
    color varchar(10), Paul int, John int, Tim int, Eric int);
insert tbl select 
    'Red' ,1 ,5 ,1 ,3 union all select
    'Green' ,8 ,4 ,3 ,5 union all select
    'Blue' ,2 ,2 ,9 ,1;

Query 1:

select *
from tbl
unpivot (value for name in ([Paul],[John],[Tim],[Eric])) up
pivot (max(value) for color in ([Red],[Green],[Blue])) p

Results:

| NAME | RED | GREEN | BLUE |
-----------------------------
| Eric |   3 |     5 |    1 |
| John |   5 |     4 |    2 |
| Paul |   1 |     8 |    2 |
|  Tim |   1 |     3 |    9 |

Additional Notes:

  1. Given a table name, you can determine all the column names from sys.columns or FOR XML trickery using local-name().
  2. You can also build up the list of distinct colors (or values for one column) using FOR XML.
  3. The above can be combined into a dynamic sql batch to handle any table.

How to get today's Date?

Is there are more correct way?

Yes, there is.

LocalDate.now( 
    ZoneId.of( "America/Montreal" ) 
).atStartOfDay(
    ZoneId.of( "America/Montreal" )
)

java.time

Java 8 and later now has the new java.time framework built-in. See Tutorial. Inspired by Joda-Time, defined by JSR 310, and extended by the ThreeTen-Extra project.

Examples

Some examples follow, using java.time. Note how they specify a time zone. If omitted, your JVM’s current default time zone. That default can vary, even changing at any moment during runtime, so I suggest you specify a time zone explicitly rather than rely implicitly on the default.

Here is an example of date-only, without time-of-day nor time zone.

ZoneId zonedId = ZoneId.of( "America/Montreal" );
LocalDate today = LocalDate.now( zonedId );
System.out.println( "today : " + today );

today : 2015-10-19

Here is an example of getting current date-time.

ZoneId zonedId = ZoneId.of( "America/Montreal" );
ZonedDateTime zdt = ZonedDateTime.now( zonedId );
System.out.println( "zdt : " + zdt );

When run:

zdt : 2015-10-19T18:07:02.910-04:00[America/Montreal]

First Moment Of The Day

The Question asks for the date-time where the time is set to zero. This assumes the first moment of the day is always the time 00:00:00.0 but that is not always the case. Daylight Saving Time (DST) and perhaps other anomalies mean the day may begin at a different time such as 01:00.0.

Fortunately, java.time has a facility to determine the first moment of a day appropriate to a particular time zone, LocalDate::atStartOfDay. Let's see some code using the LocalDate named today and the ZoneId named zoneId from code above.

ZonedDateTime todayStart = today.atStartOfDay( zoneId );

zdt : 2015-10-19T00:00:00-04:00[America/Montreal]

Interoperability

If you must have a java.util.Date for use with classes not yet updated to work with the java.time types, convert. Call the java.util.Date.from( Instant instant ) method.

java.util.Date date = java.util.Date.from( zdt.toInstant() );

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.

Where to obtain the java.time classes?

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

How do I prevent mails sent through PHP mail() from going to spam?

$fromMail = 'set your from mail';
$boundary = str_replace(" ", "", date('l jS \of F Y h i s A'));
$subjectMail = "New design submitted by " . $userDisplayName;


$contentHtml = '<div>Dear Admin<br /><br />The following design is submitted by '. $userName .'.<br /><br /><a href="'.$sdLink.'"><b>Click here</b></a> to check the design.</div>';
$contentHtml .= '<div><a href="'.$imageUrl.'"><img src="'.$imageUrl.'" width="250" height="95" border="0" alt="my picture"></a></div>';
$contentHtml .= '<div>Name : '.$name.'<br />Description : '. $description .'</div>';

$headersMail = '';
$headersMail .= 'From: ' . $fromMail . "\r\n" . 'Reply-To: ' . $fromMail . "\r\n";
$headersMail .= 'Return-Path: ' . $fromMail . "\r\n";
$headersMail .= 'MIME-Version: 1.0' . "\r\n";
$headersMail .= "Content-Type: multipart/alternative; boundary = \"" . $boundary . "\"\r\n\r\n";
$headersMail .= '--' . $boundary . "\r\n";
$headersMail .= 'Content-Type: text/html; charset=ISO-8859-1' . "\r\n";
$headersMail .= 'Content-Transfer-Encoding: base64' . "\r\n\r\n";
$headersMail .= rtrim(chunk_split(base64_encode($contentHtml)));

try {
    if (mail($toMail, $subjectMail, "", $headersMail)) {
        $status = 'success';
        $msg = 'Mail sent successfully.';
    } else {
        $status = 'failed';
        $msg = 'Unable to send mail.';
    }
} catch(Exception $e) {
    $msg = $e->getMessage();
}

This works fine for me.It includes mail with image and a link and works for all sorts of mail ids. The clue is to use all the header perfectly.

If you are testing it from localhost, then set the below before checking:

How to set mail send from localhost xampp:

  1. comment everything in D:/xampp/sendmail/sendmail.ini and mention the below under

    [sendmail]

    smtp_server=smtp.gmail.com smtp_port=587 error_logfile=error.log debug_logfile=debug.log [email protected] auth_password=your-mail-password [email protected]

  2. In D:/xampp/php/php.ini a. Under

    [mail function]

    SMTP = smtp.gmail.com smtp_port = 587

b. set sendmail_from = [email protected] c. uncomment sendmail_path = "\"D:\xamp\sendmail\sendmail.exe\" -t" Hence it should be look like below

sendmail_path = "\"D:\xamp\sendmail\sendmail.exe\" -t"

d. comment sendmail_path="D:\xamp\mailtodisk\mailtodisk.exe" Hence it should be look like below

;sendmail_path="D:\xamp\mailtodisk\mailtodisk.exe"

e. mail.add_x_header=Off

PHP file_get_contents() returns "failed to open stream: HTTP request failed!"

I'm not sure about the parameters(mpaction, format), if they are specified for the amazonaws page or ##.##.

Try to urlencode() the url.

What are type hints in Python 3.5?

Adding to Jim's elaborate answer:

Check the typing module -- this module supports type hints as specified by PEP 484.

For example, the function below takes and returns values of type str and is annotated as follows:

def greeting(name: str) -> str:
    return 'Hello ' + name

The typing module also supports:

  1. Type aliasing.
  2. Type hinting for callback functions.
  3. Generics - Abstract base classes have been extended to support subscription to denote expected types for container elements.
  4. User-defined generic types - A user-defined class can be defined as a generic class.
  5. Any type - Every type is a subtype of Any.

Copy table without copying data

Try

CREATE TABLE foo LIKE bar;

so the keys and indexes are copied over as, well.

Documentation

PowerShell Script to Find and Replace for all Files with a Specific Extension

This approach works well:

gci C:\Projects *.config -recurse | ForEach {
  (Get-Content $_ | ForEach {$_ -replace "old", "new"}) | Set-Content $_ 
}
  • Change "old" and "new" to their corresponding values (or use variables).
  • Don't forget the parenthesis -- without which you will receive an access error.

Why does overflow:hidden not work in a <td>?

I'm not familiar with the specific issue, but you could stick a div, etc inside the td and set overflow on that.

How to get Activity's content view?

You can get the view Back if you put an ID to your Layout.

<RelativeLayout
    android:id="@+id/my_relative_layout_id"

And call it from findViewById ...

Wait until all jQuery Ajax requests are done?

If you want to know when all ajax requests are finished in your document, no matter how many of them exists, just use $.ajaxStop event this way:

$(document).ajaxStop(function () {
  // 0 === $.active
});

In this case, neither you need to guess how many requests are happening in the application, that might finish in the future, nor dig into functions complex logic or find which functions are doing HTTP(S) requests.

$.ajaxStop here can also be bound to any HTML node that you think might be modified by requst.


Update:
If you want to stick with ES syntax, then you can use Promise.all for known ajax methods:

Promise.all([ajax1(), ajax2()]).then(() => {
  // all requests finished successfully
}).catch(() => {
  // all requests finished but one or more failed
})

An interesting point here is that it works both with Promises and $.ajax requests.

Here is the jsFiddle demonstration.


Update 2:
Yet more recent version using async/await syntax:

try {
  const results = await Promise.all([ajax1(), ajax2()])
  // do other actions
} catch(ex) { }

How to expand 'select' option width after the user wants to select an option

I fixed my problem with the following code:

_x000D_
_x000D_
<div style="width: 180px; overflow: hidden;">_x000D_
   <select style="width: auto;" name="abc" id="10">_x000D_
     <option value="-1">AAAAAAAAAAA</option>_x000D_
     <option value="123">123</option>_x000D_
   </select>_x000D_
</div>
_x000D_
_x000D_
_x000D_

Hope it helps!

Powershell Active Directory - Limiting my get-aduser search to a specific OU [and sub OUs]

If I understand you correctly, you need to use -SearchBase:

Get-ADUser -SearchBase "OU=Accounts,OU=RootOU,DC=ChildDomain,DC=RootDomain,DC=com" -Filter *

Note that Get-ADUser defaults to using

 -SearchScope Subtree

so you don't need to specify it. It's this that gives you all sub-OUs (and sub-sub-OUs, etc.).

What is the reason behind "non-static method cannot be referenced from a static context"?

A static method relates an action to a type of object, whereas the non static method relates an action to an instance of that type of object. Typically it is a method that does something with relation to the instance.

Ex:

class Car might have a wash method, which would indicate washing a particular car, whereas a static method would apply to the type car.

Webdriver and proxy server for firefox

For PAC based urls

 Proxy proxy = new Proxy();
 proxy.setProxyType(Proxy.ProxyType.PAC);
 proxy.setProxyAutoconfigUrl("http://some-server/staging.pac");
 DesiredCapabilities capabilities = new DesiredCapabilities();
 capabilities.setCapability(CapabilityType.PROXY, proxy);
 return new FirefoxDriver(capabilities);

I hope this could help.

How to set Apache Spark Executor memory

you mentioned that you are running yourcode interactivly on spark-shell so, while doing if no proper value is set for driver-memory or executor memory then spark defaultly assign some value to it, which is based on it's properties file(where default value is being mentioned).

I hope you are aware of the fact that there is one driver(master node) and worker-node(where executors are get created and processed), so basically two types of space is required by the spark program,so if you want to set driver memory then when start spark-shell .

spark-shell --driver-memory "your value" and to set executor memory : spark-shell --executor-memory "your value"

then I think you are good to go with the desired value of the memory that you want your spark-shell to use.

Produce a random number in a range using C#

Something like:

var rnd = new Random(DateTime.Now.Millisecond);
int ticks = rnd.Next(0, 3000);

How to execute an Oracle stored procedure via a database link

check http://www.tech-archive.net/Archive/VB/microsoft.public.vb.database.ado/2005-08/msg00056.html

one needs to use something like

cmd.CommandText = "BEGIN foo@v; END;" 

worked for me in vb.net, c#

Display encoded html with razor

You can also simply use the HtmlString class

    @(new HtmlString(Model.Content))

How to view the current heap size that an application is using?

Personal favourite for when jvisualvm is overkill or you need cli-only: jvmtop

JvmTop 0.8.0 alpha   amd64  8 cpus, Linux 2.6.32-27, load avg 0.12
https://github.com/patric-r/jvmtop

PID MAIN-CLASS      HPCUR HPMAX NHCUR NHMAX    CPU     GC    VM USERNAME   #T DL
3370 rapperSimpleApp  165m  455m  109m  176m  0.12%  0.00% S6U37 web        21
11272 ver.resin.Resin [ERROR: Could not attach to VM]
27338 WatchdogManager   11m   28m   23m  130m  0.00%  0.00% S6U37 web        31
19187 m.jvmtop.JvmTop   20m 3544m   13m  130m  0.93%  0.47% S6U37 web        20
16733 artup.Bootstrap  159m  455m  166m  304m  0.12%  0.00% S6U37 web        46

How to get folder directory from HTML input type "file" or any other way?

Stumbled on this page as well, and then found out this is possible with just javascript (no plugins like ActiveX or Flash), but just in chrome:

https://plus.google.com/+AddyOsmani/posts/Dk5UhZ6zfF3

Basically, they added support for a new attribute on the file input element "webkitdirectory". You can use it like this:

<input type="file" id="ctrl" webkitdirectory directory multiple/>

It allows you to select directories. The multiple attribute is a good fallback for browsers that support multiple file selection but not directory selection.

When you select a directory the files are available through the dom object for the control (document.getElementById('ctrl')), just like they are with the multiple attribute. The browsers adds all files in the selected directory to that list recursively.

You can already add the directory attribute as well in case this gets standardized at some point (couldn't find any info regarding that)

How can I get two form fields side-by-side, with each field’s label above the field, in CSS?

<form>
  <label for="company">
    <span>Company Name</span>
    <input type="text" id="company" />
  </label>
  <label for="contact">
    <span>Contact Name</span>
    <input type="text" id="contact" />
  </label>
</form>

label { width: 200px; float: left; margin: 0 20px 0 0; }
span { display: block; margin: 0 0 3px; font-size: 1.2em; font-weight: bold; }
input { width: 200px; border: 1px solid #000; padding: 5px; }

Illustrated at http://jsfiddle.net/H3y8j/

How do I resize an image using PIL and maintain its aspect ratio?

If you are trying to maintain the same aspect ratio, then wouldn't you resize by some percentage of the original size?

For example, half the original size

half = 0.5
out = im.resize( [int(half * s) for s in im.size] )

Difference between java.exe and javaw.exe

The difference is in the subsystem that each executable targets.

  • java.exe targets the CONSOLE subsystem.
  • javaw.exe targets the WINDOWS subsystem.

Javascript extends class

Douglas Crockford has some very good explanations of inheritance in JavaScript:

  1. prototypal inheritance: the 'natural' way to do things in JavaScript
  2. classical inheritance: closer to what you find in most OO languages, but kind of runs against the grain of JavaScript

Converting Dictionary to List?

Converting from dict to list is made easy in Python. Three examples:

>> d = {'a': 'Arthur', 'b': 'Belling'}

>> d.items()
[('a', 'Arthur'), ('b', 'Belling')]

>> d.keys()
['a', 'b']

>> d.values()
['Arthur', 'Belling']

Truncate all tables in a MySQL database in one command?

We can write a bash script like below

truncate_tables_in_mysql() {
    type mysql >/dev/null 2>&1 && echo "MySQL present." || sudo apt-get install -y mysql-client
    
    tables=$(mysql -h 127.0.0.1 -P $MYSQL_PORT -u $MYSQL_USER  -p$MYSQL_PASSWORD -e "USE $BACKEND_DATABASE;    
SHOW TABLES;")
    tables_list=($tables)
    
    query_string="USE $BACKEND_DATABASE; SET FOREIGN_KEY_CHECKS = 0;"
    for table in "${tables_list[@]:1}"
    do
        query_string="$query_string TRUNCATE TABLE \`$table\`; "
    done
    query_string="$query_string SET FOREIGN_KEY_CHECKS = 1;"
    
    mysql -h 127.0.0.1 -P $MYSQL_PORT -u $MYSQL_USER -p$MYSQL_PASSWORD -e "$query_string"
}

You can replace env variables with your MySQL details. Using one command you can truncate all the tables in a DB.

Convert array of indices to 1-hot encoded numpy array

Using a Neuraxle pipeline step:

  1. Set up your example
import numpy as np
a = np.array([1,0,3])
b = np.array([[0,1,0,0], [1,0,0,0], [0,0,0,1]])
  1. Do the actual conversion
from neuraxle.steps.numpy import OneHotEncoder
encoder = OneHotEncoder(nb_columns=4)
b_pred = encoder.transform(a)
  1. Assert it works
assert b_pred == b

Link to documentation: neuraxle.steps.numpy.OneHotEncoder

Java JTable setting Column Width

Reading the remark of Kleopatra (her 2nd time she suggested to have a look at javax.swing.JXTable, and now I Am sorry I didn't have a look the first time :) ) I suggest you follow the link

I had this solution for the same problem: (but I suggest you follow the link above) On resize the table, scale the table column widths to the current table total width. to do this I use a global array of ints for the (relative) column widths):

private int[] columnWidths=null;

I use this function to set the table column widths:

public void setColumnWidths(int[] widths){
    int nrCols=table.getModel().getColumnCount();
    if(nrCols==0||widths==null){
        return;
    }
    this.columnWidths=widths.clone();

    //current width of the table:
    int totalWidth=table.getWidth();
    
    int totalWidthRequested=0;
    int nrRequestedWidths=columnWidths.length;
    int defaultWidth=(int)Math.floor((double)totalWidth/(double)nrCols);

    for(int col=0;col<nrCols;col++){
        int width = 0;
        if(columnWidths.length>col){
            width=columnWidths[col];
        }
        totalWidthRequested+=width;
    }
    //Note: for the not defined columns: use the defaultWidth
    if(nrRequestedWidths<nrCols){
        log.fine("Setting column widths: nr of columns do not match column widths requested");
        totalWidthRequested+=((nrCols-nrRequestedWidths)*defaultWidth);
    }
    //calculate the scale for the column width
    double factor=(double)totalWidth/(double)totalWidthRequested;

    for(int col=0;col<nrCols;col++){
        int width = defaultWidth;
        if(columnWidths.length>col){
            //scale the requested width to the current table width
            width=(int)Math.floor(factor*(double)columnWidths[col]);
        }
        table.getColumnModel().getColumn(col).setPreferredWidth(width);
        table.getColumnModel().getColumn(col).setWidth(width);
    }
    
}

When setting the data I call:

    setColumnWidths(this.columnWidths);

and on changing I call the ComponentListener set to the parent of the table (in my case the JScrollPane that is the container of my table):

public void componentResized(ComponentEvent componentEvent) {
    this.setColumnWidths(this.columnWidths);
}

note that the JTable table is also global:

private JTable table;

And here I set the listener:

    scrollPane=new JScrollPane(table);
    scrollPane.addComponentListener(this);

Nginx 403 forbidden for all files

I was facing the same issue but above solutions did not help.

So, after lot of struggle I found out that sestatus was set to enforce which blocks all the ports and by setting it to permissive all the issues were resolved.

sudo setenforce 0

Hope this helps someone like me.

What's the name for hyphen-separated case?

There is no standardized name.

Libraries like jquery and lodash refer it as kebab-case. So does Vuejs javascript framework. However, I am not sure whether it's safe to declare that it's referred as kebab-case in javascript world.

How to get first item from a java.util.Set?

From the Oracle docs:

As implied by its name, this interface models the mathematical set abstraction.

In Set Theory, "a "set" is a collection of distinct objects, considered as an object in its own right." - [Wikipedia - Set].

Mathematically, elements in sets are not individualised. Their only identity is derived from their presence in the set. Therefore, there is no point in getting the "first" element in a set, as conceptually such a task is illogical.

There may be no point to getting the "first" element from a set, but if all you need is to get one single object from a set (with no guarantees as to which object that is) you can do the following:

for(String aSiteId: siteIdSet) {
    siteId = aSiteId;
    break;
}

This is a slightly shorter way (than the method you posted) to get the "first" object of a Set, however since an Iterator is still being created (under the hood) it does not grant any performance benefit.

Center a DIV horizontally and vertically

Here's a demo: http://www.w3.org/Style/Examples/007/center-example

A method (JSFiddle example)

CSS:

html, body {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
    display: table
}
#content {
    display: table-cell;
    text-align: center;
    vertical-align: middle;
}

HTML:

<div id="content">
    Content goes here
</div>

Another method (JSFiddle example)

CSS

body, html, #wrapper {
    width: 100%;
    height: 100%
}
#wrapper {
    display: table
}
#main {
    display: table-cell;
    vertical-align: middle;
    text-align:center
}

HTML

<div id="wrapper">
<div id="main">
    Content goes here
</div>
</div>

Emulator: ERROR: x86 emulation currently requires hardware acceleration

A more detailed answer for dummies like me:

  1. Open the SDK manager open sdk
  2. Select the SDK Tools tab. SDK tools tab
  3. Download – Make sure that intel x86 Emulator Accelerator (HAXM) is downloaded. haxm download
  4. Install – Now that HAXM is downloaded, make sure it is installed. In the SDK window it will show you where the SDK is located on your computer: get SDK location Click/tap 3 times quickly to highlight this text and copy the folder location. Open the file explorer and paste in the file location. From here you can search “hax” to find the folder location for HAXM stuff. Once a file comes up in the search results, right click and select “open file location”. For me the location was C:\Users\Datu1\AppData\Local\Android\Sdk\extras\intel\Hardware_Accelerated_Execution_Manager . Find the file intelhaxm-android.exe and open/run it. haxm-android.exe file Follow the instructions when it runs. You may wish to run haxm_check as an administrator (it’s in this same folder), but it may or may not work for you. The surefire way to tell if you can run hardware acceleration and if it’s enabled is to go to your computer’s bios settings from the startup menu.
  5. BIOS settings – Make sure hardware acceleration is enabled in your BIOS settings. The way to do this may vary a bit from system to system. You may need to press f10 or esc on startup. But with most (updated) Windows 10 computers you can access the BIOS settings by doing the following: type “advanced startup” in the Windows search bar; click on “change advanced startup uptions:” when it comes up. Click “Restart now”. After your computer restarts click on Troubleshoot. Troubleshoot Windows startup Click advanced options >firmware settings, then restart to change EUFI firmware settings. Wait for the restart then select the menu option for bios settings. With Intel processors the steps will be as follows or similar: Press the right arrow to go to the Configuration tab. Arrow down to Intel Virtual/Virtualizaion Technology and turn it on (should say Enabled). Enable virtualization in bios Exit and save changes.

  6. If Virtual Technology was previously disabled in your bios settings You will need to run the intelhaxm-android.exe file now to install haxm.

  7. Try restarting Android Studio and running your emulator again. If it’s still not working, restart your computer and try again, it should work.

NOTE: if you have Windows Hyper-V turned on this will cause you to not be able to run haxm. If you are having an issue with Hyper-V, make sure it is turned off in your settings: search in the Windows bar for “hyper”; the search result should take you to “Turn Windows features on or off”. Then make sure all the Hyper-V boxes are unchecked.
disable hyper-v

What is ToString("N0") format?

Checkout the following article on MSDN about examples of the N format. This is also covered in the Standard Numeric Format Strings article.

Relevant excerpts:

//       Formatting of 1054.32179:
//          N:                     1,054.32 
//          N0:                    1,054 
//          N1:                    1,054.3 
//          N2:                    1,054.32 
//          N3:                    1,054.322 

When precision specifier controls the number of fractional digits in the result string, the result string reflects a number that is rounded to a representable result nearest to the infinitely precise result. If there are two equally near representable results:

  • On the .NET Framework and .NET Core up to .NET Core 2.0, the runtime selects the result with the greater least significant digit (that is, using MidpointRounding.AwayFromZero).
  • On .NET Core 2.1 and later, the runtime selects the result with an even least significant digit (that is, using MidpointRounding.ToEven).

How to fix: "HAX is not working and emulator runs in emulation mode"

In my case, this error was fixed when I set HAXM memory equal to AVD memory. HAXM memory 1024 MB = AVD memory 1024 MB

Hax is enabled
Hax ram_size 0x40000000
HAX is working and emulator runs in fast virt mode.

Upto this point the error should be fixed.

Now I'm listing my specific environment in case it could be of some help for someone using OS X.

OS X El Capitan 10.11.4

MacBook (13-inch), 2 GHz Intel Core 2 Duo, 4 GB Ram.

Android Studio 2.1

Marshmallow (23) x86 didn't pass the flashing Android icon screen for even hours.

Lollipop (22) x86 passed the flashing android icon screen and then showed

  • Starting Android (Optimizing x out of y apps)
  • Starting Android (Starting apps)
  • Starting Android (Updating Contacts Database)
  • Starting Android (Finishing boot) and remained stuck here for hours.

KitKat (19) x86 worked successfully and I could install the hello world there.

How to delete a cookie?

would this work?

function eraseCookie(name) {
    document.cookie = name + '=; Max-Age=0'
}

I know Max-Age causes the cookie to be a session cookie in IE when creating the cookie. Not sure how it works when deleting cookies.

How do I open workbook programmatically as read-only?

Does this work?

Workbooks.Open Filename:=filepath, ReadOnly:=True

Or, as pointed out in a comment, to keep a reference to the opened workbook:

Dim book As Workbook
Set book = Workbooks.Open(Filename:=filepath, ReadOnly:=True)

Gradients on UIView and UILabels On iPhone

This is what I got working- set UIButton in xCode's IB to transparent/clear, and no bg image.

UIColor *pinkDarkOp = [UIColor colorWithRed:0.9f green:0.53f blue:0.69f alpha:1.0];
UIColor *pinkLightOp = [UIColor colorWithRed:0.79f green:0.45f blue:0.57f alpha:1.0];

CAGradientLayer *gradient = [CAGradientLayer layer];
gradient.frame = [[shareWordButton layer] bounds];
gradient.cornerRadius = 7;
gradient.colors = [NSArray arrayWithObjects:
                   (id)pinkDarkOp.CGColor,
                   (id)pinkLightOp.CGColor,
                   nil];
gradient.locations = [NSArray arrayWithObjects:
                      [NSNumber numberWithFloat:0.0f],
                      [NSNumber numberWithFloat:0.7],
                      nil];

[[recordButton layer] insertSublayer:gradient atIndex:0];

'Incomplete final line' warning when trying to read a .csv file into R

I got this problem once when I had a single quote as part of the header. When I removed it (i.e. renamed the respective column header from Jimmy's data to Jimmys data), the function returned no warnings.

How do I detect what .NET Framework versions and service packs are installed?

There is an official Microsoft answer to this question at the following knowledge base article:

Article ID: 318785 - Last Review: November 7, 2008 - Revision: 20.1 How to determine which versions of the .NET Framework are installed and whether service packs have been applied

Unfortunately, it doesn't appear to work, because the mscorlib.dll version in the 2.0 directory has a 2.0 version, and there is no mscorlib.dll version in either the 3.0 or 3.5 directories even though 3.5 SP1 is installed ... why would the official Microsoft answer be so misinformed?

how to compare two elements in jquery

The collection results you get back from a jQuery collection do not support set-based comparison. You can use compare the individual members one by one though, there are no utilities for this that I know of in jQuery.

RAW POST using cURL in PHP

Implementation with Guzzle library:

use GuzzleHttp\Client;
use GuzzleHttp\RequestOptions;

$httpClient = new Client();

$response = $httpClient->post(
    'https://postman-echo.com/post',
    [
        RequestOptions::BODY => 'POST raw request content',
        RequestOptions::HEADERS => [
            'Content-Type' => 'application/x-www-form-urlencoded',
        ],
    ]
);

echo(
    $response->getBody()->getContents()
);

PHP CURL extension:

$curlHandler = curl_init();

curl_setopt_array($curlHandler, [
    CURLOPT_URL => 'https://postman-echo.com/post',
    CURLOPT_RETURNTRANSFER => true,

    /**
     * Specify POST method
     */
    CURLOPT_POST => true,

    /**
     * Specify request content
     */
    CURLOPT_POSTFIELDS => 'POST raw request content',
]);

$response = curl_exec($curlHandler);

curl_close($curlHandler);

echo($response);

Source code

In mocha testing while calling asynchronous function how to avoid the timeout Error: timeout of 2000ms exceeded

I find that the "solution" of just increasing the timeouts obscures what's really going on here, which is either

  1. Your code and/or network calls are way too slow (should be sub 100 ms for a good user experience)
  2. The assertions (tests) are failing and something is swallowing the errors before Mocha is able to act on them.

You usually encounter #2 when Mocha doesn't receive assertion errors from a callback. This is caused by some other code swallowing the exception further up the stack. The right way of dealing with this is to fix the code and not swallow the error.

When external code swallows your errors

In case it's a library function that you are unable to modify, you need to catch the assertion error and pass it onto Mocha yourself. You do this by wrapping your assertion callback in a try/catch block and pass any exceptions to the done handler.

it('should not fail', function (done) { // Pass reference here!

  i_swallow_errors(function (err, result) {
    try { // boilerplate to be able to get the assert failures
      assert.ok(true);
      assert.equal(result, 'bar');
      done();
    } catch (error) {
      done(error);
    }
  });
});

This boilerplate can of course be extracted into some utility function to make the test a little more pleasing to the eye:

it('should not fail', function (done) { // Pass reference here!
    i_swallow_errors(handleError(done, function (err, result) {
        assert.equal(result, 'bar');
    }));
});

// reusable boilerplate to be able to get the assert failures
function handleError(done, fn) {
    try { 
        fn();
        done();
    } catch (error) {
        done(error);
    }
}

Speeding up network tests

Other than that I suggest you pick up the advice on starting to use test stubs for network calls to make tests pass without having to rely on a functioning network. Using Mocha, Chai and Sinon the tests might look something like this

describe('api tests normally involving network calls', function() {

    beforeEach: function () {
        this.xhr = sinon.useFakeXMLHttpRequest();
        var requests = this.requests = [];

        this.xhr.onCreate = function (xhr) {
            requests.push(xhr);
        };
    },

    afterEach: function () {
        this.xhr.restore();
    }


    it("should fetch comments from server", function () {
        var callback = sinon.spy();
        myLib.getCommentsFor("/some/article", callback);
        assertEquals(1, this.requests.length);

        this.requests[0].respond(200, { "Content-Type": "application/json" },
                                 '[{ "id": 12, "comment": "Hey there" }]');
        expect(callback.calledWith([{ id: 12, comment: "Hey there" }])).to.be.true;
    });

});

See Sinon's nise docs for more info.

When to use malloc for char pointers

malloc is for allocating memory on the free-store. If you have a string literal that you do not want to modify the following is ok:

char *literal = "foo";

However, if you want to be able to modify it, use it as a buffer to hold a line of input and so on, use malloc:

char *buf = (char*) malloc(BUFSIZE); /* define BUFSIZE before */
// ...
free(buf);

Comma separated results in SQL

this works in sql server 2016

USE AdventureWorks
GO
DECLARE @listStr VARCHAR(MAX)
SELECT @listStr = COALESCE(@listStr+',' ,'') + Name
FROM Production.Product
SELECT @listStr
GO

javascript node.js next()

It is naming convention used when passing callbacks in situations that require serial execution of actions, e.g. scan directory -> read file data -> do something with data. This is in preference to deeply nesting the callbacks. The first three sections of the following article on Tim Caswell's HowToNode blog give a good overview of this:

http://howtonode.org/control-flow

Also see the Sequential Actions section of the second part of that posting:

http://howtonode.org/control-flow-part-ii

How can I get a favicon to show up in my django app?

Came across this while looking for help. I was trying to implement the favicon in my Django project and it was not showing -- wanted to add to the conversation.

While trying to implement the favicon in my Django project I renamed the 'favicon.ico' file to 'my_filename.ico' –– the image would not show. After renaming to 'favicon.ico' resolved the issue and graphic displayed. below is the code that resolved my issue:

<link rel="shortcut icon" type="image/png" href="{% static 'img/favicon.ico' %}" />

SQL Query - Change date format in query to DD/MM/YYYY

If you have a Date (or Datetime) column, look at http://dev.mysql.com/doc/refman/5.5/en/date-and-time-functions.html#function_date-format

 SELECT DATE_FORMAT(datecolumn,'%d/%m/%Y') FROM ...

Should do the job for MySQL, for SqlServer I'm sure there is an analog function. If you have a VARCHAR column, you might have at first to convert it to a date, see STR_TO_DATE for MySQL.

oracle diff: how to compare two tables?

In addition to some of the other answers provided, if you wanted to look at the differences in table structure with a table that might have the similar but differing structure, you could do this in multiple ways:

First - If using Oracle SQL Developer, you could run a describe on both tables to compare them:

descr TABLE_NAME1
descr TABLE_NAME2

Second - The first solution may not be ideal for larger tables with a lot of columns. If you only want to see the differences in the data between the two tables, then as mentioned by several others, using the SQL Minus operator should do the job.

Third - If you are using Oracle SQL Developer, and you want to compare the table structure of two tables using different schemas you can do the following:

  1. Select "Tools"
  2. Select "Database Diff"
  3. Select "Source Connection"
  4. Select "Destination Connection"
  5. Select the "Standard Object Types" you want to compare
  6. Enter the "Table Name"
  7. Click "Next" until you reach "Finish"
  8. Click "Finish"
  9. NOTE: In steps 3 & 4 is where you would select the differing schemas in which the objects exist that you want to compare.

Fourth - If the tables two tables you wish to compare have more columns, are in the same schema, have no need to compare more than two tables and are unappealing to compare visually using the DESCR command you can use the following to compare the differences in the table structure:

select 
     a.column_name    || ' | ' || b.column_name, 
     a.data_type      || ' | ' || b.data_type, 
     a.data_length    || ' | ' || b.data_length, 
     a.data_scale     || ' | ' || b.data_scale, 
     a.data_precision || ' | ' || b.data_precision
from 
     user_tab_columns a,
     user_tab_columns b
where 
     a.table_name = 'TABLE_NAME1' 
and  b.table_name = 'TABLE_NAME2'
and  ( 
       a.data_type      <> b.data_type     or 
       a.data_length    <> b.data_length   or 
       a.data_scale     <> b.data_scale    or 
       a.data_precision <> b.data_precision
     )
and a.column_name = b.column_name;

EditText, inputType values (xml)

You can use the properties tab in eclipse to set various values.

here are all the possible values

  • none
  • text
  • textCapCharacters
  • textCapWords
  • textCapSentences
  • textAutoCorrect
  • textAutoComplete
  • textMultiLine
  • textImeMultiLine
  • textNoSuggestions
  • textUri
  • textEmailAddress
  • textEmailSubject
  • textShortMessage
  • textLongMessage
  • textPersonName
  • textPostalAddress
  • textPassword
  • textVisiblePassword
  • textWebEditText
  • textFilter
  • textPhonetic
  • textWebEmailAddress
  • textWebPassword
  • number
  • numberSigned
  • numberDecimal
  • numberPassword
  • phone
  • datetime
  • date
  • time

Check here for explanations: http://developer.android.com/reference/android/widget/TextView.html#attr_android:inputType

How to run docker-compose up -d at system start up?

You should be able to add:

restart: always 

to every service you want to restart in the docker-compose.yml file.

See: https://github.com/compose-spec/compose-spec/blob/master/spec.md#restart

How to implement class constructor in Visual Basic?

If you mean VB 6, that would be Private Sub Class_Initialize().

http://msdn.microsoft.com/en-us/library/55yzhfb2(VS.80).aspx

If you mean VB.NET it is Public Sub New() or Shared Sub New().

How to set time delay in javascript

If you need refresh, this is another posibility:

setTimeout(function () { 
    $("#jsSegurosProductos").jsGrid("refresh"); 
}, 1000);

How to Convert a Text File into a List in Python

Maybe:

crimefile = open(fileName, 'r')
yourResult = [line.split(',') for line in crimefile.readlines()]

Javascript switch vs. if...else if...else

Sometimes it's better to use neither. For example, in a "dispatch" situation, Javascript lets you do things in a completely different way:

function dispatch(funCode) {
  var map = {
    'explode': function() {
      prepExplosive();
      if (flammable()) issueWarning();
      doExplode();
    },

    'hibernate': function() {
      if (status() == 'sleeping') return;
      // ... I can't keep making this stuff up
    },
    // ...
  };

  var thisFun = map[funCode];
  if (thisFun) thisFun();
}

Setting up multi-way branching by creating an object has a lot of advantages. You can add and remove functionality dynamically. You can create the dispatch table from data. You can examine it programmatically. You can build the handlers with other functions.

There's the added overhead of a function call to get to the equivalent of a "case", but the advantage (when there are lots of cases) of a hash lookup to find the function for a particular key.

How does the ARM architecture differ from x86?

The ARM architecture was originally designed for Acorn personal computers (See Acorn Archimedes, circa 1987, and RiscPC), which were just as much keyboard-based personal computers as were x86 based IBM PC models. Only later ARM implementations were primarily targeted at the mobile and embedded market segment.

Originally, simple RISC CPUs of roughly equivalent performance could be designed by much smaller engineering teams (see Berkeley RISC) than those working on the x86 development at Intel.

But, nowadays, the fastest ARM chips have very complex multi-issue out-of-order instruction dispatch units designed by large engineering teams, and x86 cores may have something like a RISC core fed by an instruction translation unit.

So, any current differences between the two architectures are more related to the specific market needs of the product niches that the development teams are targeting. (Random opinion: ARM probably makes more in license fees from embedded applications that tend to be far more power and cost constrained. And Intel needs to maintain a performance edge in PCs and servers for their profit margins. Thus you see differing implementation optimizations.)

Passing an array by reference in C?

The C language does not support pass by reference of any type. The closest equivalent is to pass a pointer to the type.

Here is a contrived example in both languages

C++ style API

void UpdateValue(int& i) {
  i = 42;
}

Closest C equivalent

void UpdateValue(int *i) {
  *i = 42;
}

Can you use if/else conditions in CSS?

(Yes, old thread. But it turned up on top of a Google-search so others might be interested as well)

I guess the if/else-logic could be done with javascript, which in turn can dynamically load/unload stylesheets. I haven't tested this across browsers etc. but it should work. This will get you started:

http://www.javascriptkit.com/javatutors/loadjavascriptcss.shtml

Get file size, image width and height before upload

Here is a pure JavaScript example of picking an image file, displaying it, looping through the image properties, and then re-sizing the image from the canvas into an IMG tag and explicitly setting the re-sized image type to jpeg.

If you right click the top image, in the canvas tag, and choose Save File As, it will default to a PNG format. If you right click, and Save File as the lower image, it will default to a JPEG format. Any file over 400px in width is reduced to 400px in width, and a height proportional to the original file.

HTML

<form class='frmUpload'>
  <input name="picOneUpload" type="file" accept="image/*" onchange="picUpload(this.files[0])" >
</form>

<canvas id="cnvsForFormat" width="400" height="266" style="border:1px solid #c3c3c3"></canvas>
<div id='allImgProperties' style="display:inline"></div>

<div id='imgTwoForJPG'></div>

SCRIPT

<script>

window.picUpload = function(frmData) {
  console.log("picUpload ran: " + frmData);

var allObjtProperties = '';
for (objProprty in frmData) {
    console.log(objProprty + " : " + frmData[objProprty]);
    allObjtProperties = allObjtProperties + "<span>" + objProprty + ": " + frmData[objProprty] + ", </span>";
};

document.getElementById('allImgProperties').innerHTML = allObjtProperties;

var cnvs=document.getElementById("cnvsForFormat");
console.log("cnvs: " + cnvs);
var ctx=cnvs.getContext("2d");

var img = new Image;
img.src = URL.createObjectURL(frmData);

console.log('img: ' + img);

img.onload = function() {
  var picWidth = this.width;
  var picHeight = this.height;

  var wdthHghtRatio = picHeight/picWidth;
  console.log('wdthHghtRatio: ' + wdthHghtRatio);

  if (Number(picWidth) > 400) {
    var newHeight = Math.round(Number(400) * wdthHghtRatio);
  } else {
    return false;
  };

    document.getElementById('cnvsForFormat').height = newHeight;
    console.log('width: 400  h: ' + newHeight);
    //You must change the width and height settings in order to decrease the image size, but
    //it needs to be proportional to the original dimensions.
    console.log('This is BEFORE the DRAW IMAGE');
    ctx.drawImage(img,0,0, 400, newHeight);

    console.log('THIS IS AFTER THE DRAW IMAGE!');

    //Even if original image is jpeg, getting data out of the canvas will default to png if not specified
    var canvasToDtaUrl = cnvs.toDataURL("image/jpeg");
    //The type and size of the image in this new IMG tag will be JPEG, and possibly much smaller in size
    document.getElementById('imgTwoForJPG').innerHTML = "<img src='" + canvasToDtaUrl + "'>";
};
};

</script>

Here is a jsFiddle:

jsFiddle Pick, display, get properties, and Re-size an image file

In jsFiddle, right clicking the top image, which is a canvas, won't give you the same save options as right clicking the bottom image in an IMG tag.

How can I suppress the newline after a print statement?

Because python 3 print() function allows end="" definition, that satisfies the majority of issues.

In my case, I wanted to PrettyPrint and was frustrated that this module wasn't similarly updated. So i made it do what i wanted:

from pprint import PrettyPrinter

class CommaEndingPrettyPrinter(PrettyPrinter):
    def pprint(self, object):
        self._format(object, self._stream, 0, 0, {}, 0)
        # this is where to tell it what you want instead of the default "\n"
        self._stream.write(",\n")

def comma_ending_prettyprint(object, stream=None, indent=1, width=80, depth=None):
    """Pretty-print a Python object to a stream [default is sys.stdout] with a comma at the end."""
    printer = CommaEndingPrettyPrinter(
        stream=stream, indent=indent, width=width, depth=depth)
    printer.pprint(object)

Now, when I do:

comma_ending_prettyprint(row, stream=outfile)

I get what I wanted (substitute what you want -- Your Mileage May Vary)

Using Javascript: How to create a 'Go Back' link that takes the user to a link if there's no history for the tab or window?

The following code did the trick for me.

html:

<div class="back" onclick="goBackOrGoHome()">
  Back
</div>

js:

home_url = [YOUR BASE URL];

pathArray = document.referrer.split( '/' );
protocol = pathArray[0];
host = pathArray[2];

url_before = protocol + '//' + host;

url_now = window.location.protocol + "//" + window.location.host;


function goBackOrGoHome(){
  if ( url_before == url_now) {
    window.history.back();    
  }else{
    window.location = home_url;
  };
}

So, you use document.referrer to set the domain of the page you come from. Then you compare that with your current url using window.location.

If they are from the same domain, it means you are coming from your own site and you send them window.history.back(). If they are not the same, you are coming from somewhere else and you should redirect home or do whatever you like.

Using GitLab token to clone without authentication

One possible way is using a deploy token (https://docs.gitlab.com/ee/user/project/deploy_tokens). After creating the token, use:

git clone https://<username>:<deploy_token>@gitlab.example.com/tanuki/awesome_project.git 

as mentioned in the link above.

jQuery posting valid json in request body

An actual JSON request would look like this:

data: '{"command":"on"}',

Where you're sending an actual JSON string. For a more general solution, use JSON.stringify() to serialize an object to JSON, like this:

data: JSON.stringify({ "command": "on" }),

To support older browsers that don't have the JSON object, use json2.js which will add it in.


What's currently happening is since you have processData: false, it's basically sending this: ({"command":"on"}).toString() which is [object Object]...what you see in your request.

Could not create SSL/TLS secure channel, despite setting ServerCertificateValidationCallback

You are doing it right with ServerCertificateValidationCallback. This is not the problem you are facing. The problem you are facing is most likely the version of SSL/TLS protocol.

For example, if your server offers only SSLv3 and TLSv10 and your client needs TLSv12 then you will receive this error message. What you need to do is to make sure that both client and server have a common protocol version supported.

When I need a client that is able to connect to as many servers as possible (rather than to be as secure as possible) I use this (together with setting the validation callback):

  ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3 | SecurityProtocolType.Tls | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls12;

parent & child with position fixed, parent overflow:hidden bug

If you want to hide overflow on fixed-position elements, the simplest approach I've found is to place the element inside a container element, and apply position:fixed and overflow:hidden to that element instead of the contained element (you must remove position:fixed from the contained element for this to work). The content of the fixed container should then be clipped as expected.

In my case I was having trouble with using object-fit:cover on a fixed-position element (it was spilling outside the bounds of the page body, regardless of overflow:hidden). Placing it inside a fixed container with overflow:hidden on the container fixed the issue.

Make Vim show ALL white spaces as a character

As of patch 7.4.710 you can now set a character to show in place of space using listchars!

:set listchars+=space:?

So, to show ALL white space characters as a character you can do the following:

:set listchars=eol:¬,tab:>·,trail:~,extends:>,precedes:<,space:?
:set list

Discussion on mailing list: https://groups.google.com/forum/?fromgroups#!topic/vim_dev/pjmW6wOZW_Q

Xcode "Build and Archive" from command line

try xctool, it is a replacement for Apple's xcodebuild that makes it easier to build and test iOS and Mac products. It's especially helpful for continuous integration. It has a few extra features:

  1. Runs the same tests as Xcode.app.
  2. Structured output of build and test results.
  3. Human-friendly, ANSI-colored output.

No.3 is extremely useful. I don't if anyone can read the console output of xcodebuild, I can't, usually it gave me one line with 5000+ characters. Even harder to read than a thesis paper.

xctool: https://github.com/facebook/xctool

How to change TextField's height and width?

Screenshot:

enter image description here


Widget _buildTextField() {
  final maxLines = 5;

  return Container(
    margin: EdgeInsets.all(12),
    height: maxLines * 24.0,
    child: TextField(
      maxLines: maxLines,
      decoration: InputDecoration(
        hintText: "Enter a message",
        fillColor: Colors.grey[300],
        filled: true,
      ),
    ),
  );
}

Byte Array to Hex String

If you have a numpy array, you can do the following:

>>> import numpy as np
>>> a = np.array([133, 53, 234, 241])
>>> a.astype(np.uint8).data.hex()
'8535eaf1'

Python Pandas Replacing Header with Top Row

Here's a simple trick that defines column indices "in place". Because set_index sets row indices in place, we can do the same thing for columns by transposing the data frame, setting the index, and transposing it back:

df = df.T.set_index(0).T

Note you may have to change the 0 in set_index(0) if your rows have a different index already.

Get list from pandas dataframe column or row?

Assuming the name of the dataframe after reading the excel sheet is df, take an empty list (e.g. dataList), iterate through the dataframe row by row and append to your empty list like-

dataList = [] #empty list
for index, row in df.iterrows(): 
    mylist = [row.cluster, row.load_date, row.budget, row.actual, row.fixed_price]
    dataList.append(mylist)

Or,

dataList = [] #empty list
for row in df.itertuples(): 
    mylist = [row.cluster, row.load_date, row.budget, row.actual, row.fixed_price]
    dataList.append(mylist)

No, if you print the dataList, you will get each rows as a list in the dataList.

Can I force a UITableView to hide the separator between empty cells?

For Swift:

override func viewDidLoad() {
    super.viewDidLoad()
    tableView.tableFooterView = UIView()  // it's just 1 line, awesome!
}

How to instantiate, initialize and populate an array in TypeScript?

If you would like to 'add' additional items to a page, you may want to create an array of maps. This is how I created an array of maps and then added results to it:

import { Product } from '../models/product';

products: Array<Product>;          // Initialize the array.

[...]

let i = 0;
this.service.products( i , (result) => {

    if ( i == 0 ) {
        // Create the first element of the array.
        this.products = Array(result);
    } else { 
        // Add to the array of maps.
        this.products.push(result);
    }

});

Where product.ts look like...

export class Product {
    id: number;
    [...]
}

How to trigger an event after using event.preventDefault()

The approach I use is this:

$('a').on('click', function(event){
    if (yourCondition === true) { //Put here the condition you want
        event.preventDefault(); // Here triggering stops
        // Here you can put code relevant when event stops;
        return;
    }
    // Here your event works as expected and continue triggering
    // Here you can put code you want before triggering
});

alternatives to REPLACE on a text or ntext datatype

IF your data won't overflow 4000 characters AND you're on SQL Server 2000 or compatibility level of 8 or SQL Server 2000:

UPDATE [CMS_DB_test].[dbo].[cms_HtmlText] 
SET Content = CAST(REPLACE(CAST(Content as NVarchar(4000)),'ABC','DEF') AS NText)
WHERE Content LIKE '%ABC%' 

For SQL Server 2005+:

UPDATE [CMS_DB_test].[dbo].[cms_HtmlText] 
SET Content = CAST(REPLACE(CAST(Content as NVarchar(MAX)),'ABC','DEF') AS NText)
WHERE Content LIKE '%ABC%' 

The provider is not compatible with the version of Oracle client

For anyone still having this problem: based on this article

http://oradim.blogspot.com/2009/09/odpnet-provider-is-not-compatible-with.html

I found out that my server was missing the Microsoft C++ Visual Runtime Library - I had it on my dev machine because of the Visual Studio installed. I downloaded and installed the (currently) most recent version of the library from here:

http://www.microsoft.com/en-us/download/details.aspx?id=13523

Ran the setup and the oracle call from C# made it!

How do you automatically set the focus to a textbox when a web page loads?

As a general advice, I would recommend not stealing the focus from the address bar. (Jeff already talked about that.)

Web page can take some time to load, which means that your focus change can occur some long time after the user typed the pae URL. Then he could have changed his mind and be back to url typing while you will be loading your page and stealing the focus to put it in your textbox.

That's the one and only reason that made me remove Google as my start page.

Of course, if you control the network (local network) or if the focus change is to solve an important usability issue, forget all I just said :)

Java AES and using my own Key

import java.security.Key;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import sun.misc.*;
import java.io.BufferedReader;
import java.io.FileReader;

public class AESFile 
{
private static String algorithm = "AES";
private static byte[] keyValue=new byte[] {'0','2','3','4','5','6','7','8','9','1','2','3','4','5','6','7'};// your key

    // Performs Encryption
    public static String encrypt(String plainText) throws Exception 
    {
            Key key = generateKey();
            Cipher chiper = Cipher.getInstance(algorithm);
            chiper.init(Cipher.ENCRYPT_MODE, key);
            byte[] encVal = chiper.doFinal(plainText.getBytes());
            String encryptedValue = new BASE64Encoder().encode(encVal);
            return encryptedValue;
    }

    // Performs decryption
    public static String decrypt(String encryptedText) throws Exception 
    {
            // generate key 
            Key key = generateKey();
            Cipher chiper = Cipher.getInstance(algorithm);
            chiper.init(Cipher.DECRYPT_MODE, key);
            byte[] decordedValue = new BASE64Decoder().decodeBuffer(encryptedText);
            byte[] decValue = chiper.doFinal(decordedValue);
            String decryptedValue = new String(decValue);
            return decryptedValue;
    }

//generateKey() is used to generate a secret key for AES algorithm
    private static Key generateKey() throws Exception 
    {
            Key key = new SecretKeySpec(keyValue, algorithm);
            return key;
    }

    // performs encryption & decryption 
    public static void main(String[] args) throws Exception 
    {
        FileReader file = new FileReader("C://myprograms//plaintext.txt");
        BufferedReader reader = new BufferedReader(file);
        String text = "";
        String line = reader.readLine();
    while(line!= null)
        {
            text += line;
    line = reader.readLine();
        }
        reader.close();
    System.out.println(text);

            String plainText = text;
            String encryptedText = AESFile.encrypt(plainText);
            String decryptedText = AESFile.decrypt(encryptedText);

            System.out.println("Plain Text : " + plainText);
            System.out.println("Encrypted Text : " + encryptedText);
            System.out.println("Decrypted Text : " + decryptedText);
    }
}

How do I select an entire row which has the largest ID in the table?

One can always go for analytical functions as well which will give you more control

select tmp.row from ( select row, rank() over(partition by id order by id desc ) as rnk from table) tmp where tmp.rnk=1

If you face issue with rank() function depending on the type of data then one can choose from row_number() or dense_rank() too.

Changing three.js background to transparent or other color

A full answer: (Tested with r71)

To set a background color use:

renderer.setClearColor( 0xffffff ); // white background - replace ffffff with any hex color

If you want a transparent background you will have to enable alpha in your renderer first:

renderer = new THREE.WebGLRenderer( { alpha: true } ); // init like this
renderer.setClearColor( 0xffffff, 0 ); // second param is opacity, 0 => transparent

View the docs for more info.

Number format in excel: Showing % value without multiplying with 100

You just have to change to a Custom format - right click and select format and at the bottom of the list is custom.

 0.00##\%;[Red](0.00##\%)

The first part of custom format is your defined format you posted. Everything after the semicolon is for negative numbers. [RED] tells Excel to make the negative numbers red and the () make sure that negative number is in parentheses.

How to right-align form input boxes?

Use some tag, to aligning the input element. So

<form>
   <div>
     <input>
     <br />
     <input>
    </div>
</form>

    .mydiv
     {
        width: 500px;
        height: 250px;
        display: table;
        text-align: right;
     }

Useful example of a shutdown hook in Java?

You could do the following:

  • Let the shutdown hook set some AtomicBoolean (or volatile boolean) "keepRunning" to false
  • (Optionally, .interrupt the working threads if they wait for data in some blocking call)
  • Wait for the working threads (executing writeBatch in your case) to finish, by calling the Thread.join() method on the working threads.
  • Terminate the program

Some sketchy code:

  • Add a static volatile boolean keepRunning = true;
  • In run() you change to

    for (int i = 0; i < N && keepRunning; ++i)
        writeBatch(pw, i);
    
  • In main() you add:

    final Thread mainThread = Thread.currentThread();
    Runtime.getRuntime().addShutdownHook(new Thread() {
        public void run() {
            keepRunning = false;
            mainThread.join();
        }
    });
    

That's roughly how I do a graceful "reject all clients upon hitting Control-C" in terminal.


From the docs:

When the virtual machine begins its shutdown sequence it will start all registered shutdown hooks in some unspecified order and let them run concurrently. When all the hooks have finished it will then run all uninvoked finalizers if finalization-on-exit has been enabled. Finally, the virtual machine will halt.

That is, a shutdown hook keeps the JVM running until the hook has terminated (returned from the run()-method.

why windows 7 task scheduler task fails with error 2147942667

I had the same problem, on Windows7.

I was getting error 2147942667 and a report of being unable to run c:\windows\system32\CMD.EXE. I tried with and without double quotes in the Script and Start-in and it made no difference. Then I tried replacing all path references to mapped network drives and with UNC references (\Server1\Sharexx\my_scripts\run_this.cmd) and that fixed it for me. Pat.

Maven Run Project

1. Edit POM.xml

Add the following property in pom.xml. Make sure you use the fully qualified class name (i.e. with package name) which contains the main method:

<properties>
        <exec.mainClass>fully-qualified-class-name</exec.mainClass>
</properties>

2. Run Command

Now from the terminal, trigger the following command:

mvn clean compile exec:java

NOTE You can pass further arguments via -Dexec.args="xxx" flag.

Is there any 'out-of-the-box' 2D/3D plotting library for C++?

Hey! I'm the developer of wxMathPlot! The project is active: I just took a long time to get a new release, because the code needed a partial rewriting to introduce new features. Take a look to the new 0.1.0 release: it is a great improvement from old versions. Anyway, it doesn't provide 3D (even if I always thinking about it...).

Android - drawable with rounded corners at the top only

You may need read this https://developer.android.com/guide/topics/resources/drawable-resource.html#Shape

and below there is a Note.

Note Every corner must (initially) be provided a corner radius greater than 1, or else no corners are rounded. If you want specific corners to not be rounded, a work-around is to use android:radius to set a default corner radius greater than 1, but then override each and every corner with the values you really want, providing zero ("0dp") where you don't want rounded corners.

Check if checkbox is checked with jQuery

Actually, according to jsperf.com, The DOM operations are fastest, then $().prop() followed by $().is()!!

Here are the syntaxes :

var checkbox = $('#'+id);
/* OR var checkbox = $("input[name=checkbox1]"); whichever is best */

/* The DOM way - The fastest */
if(checkbox[0].checked == true)
   alert('Checkbox is checked!!');

/* Using jQuery .prop() - The second fastest */
if(checkbox.prop('checked') == true)
   alert('Checkbox is checked!!');

/* Using jQuery .is() - The slowest in the lot */
if(checkbox.is(':checked') == true)
   alert('Checkbox is checked!!');

I personally prefer .prop(). Unlike .is(), It can also be used to set the value.

Using StringWriter for XML Serialization

<TL;DR> The problem is rather simple, actually: you are not matching the declared encoding (in the XML declaration) with the datatype of the input parameter. If you manually added <?xml version="1.0" encoding="utf-8"?><test/> to the string, then declaring the SqlParameter to be of type SqlDbType.Xml or SqlDbType.NVarChar would give you the "unable to switch the encoding" error. Then, when inserting manually via T-SQL, since you switched the declared encoding to be utf-16, you were clearly inserting a VARCHAR string (not prefixed with an upper-case "N", hence an 8-bit encoding, such as UTF-8) and not an NVARCHAR string (prefixed with an upper-case "N", hence the 16-bit UTF-16 LE encoding).

The fix should have been as simple as:

  1. In the first case, when adding the declaration stating encoding="utf-8": simply don't add the XML declaration.
  2. In the second case, when adding the declaration stating encoding="utf-16": either
    1. simply don't add the XML declaration, OR
    2. simply add an "N" to the input parameter type: SqlDbType.NVarChar instead of SqlDbType.VarChar :-) (or possibly even switch to using SqlDbType.Xml)

(Detailed response is below)


All of the answers here are over-complicated and unnecessary (regardless of the 121 and 184 up-votes for Christian's and Jon's answers, respectively). They might provide working code, but none of them actually answer the question. The issue is that nobody truly understood the question, which ultimately is about how the XML datatype in SQL Server works. Nothing against those two clearly intelligent people, but this question has little to nothing to do with serializing to XML. Saving XML data into SQL Server is much easier than what is being implied here.

It doesn't really matter how the XML is produced as long as you follow the rules of how to create XML data in SQL Server. I have a more thorough explanation (including working example code to illustrate the points outlined below) in an answer on this question: How to solve “unable to switch the encoding” error when inserting XML into SQL Server, but the basics are:

  1. The XML declaration is optional
  2. The XML datatype stores strings always as UCS-2 / UTF-16 LE
  3. If your XML is UCS-2 / UTF-16 LE, then you:
    1. pass in the data as either NVARCHAR(MAX) or XML / SqlDbType.NVarChar (maxsize = -1) or SqlDbType.Xml, or if using a string literal then it must be prefixed with an upper-case "N".
    2. if specifying the XML declaration, it must be either "UCS-2" or "UTF-16" (no real difference here)
  4. If your XML is 8-bit encoded (e.g. "UTF-8" / "iso-8859-1" / "Windows-1252"), then you:
    1. need to specify the XML declaration IF the encoding is different than the code page specified by the default Collation of the database
    2. you must pass in the data as VARCHAR(MAX) / SqlDbType.VarChar (maxsize = -1), or if using a string literal then it must not be prefixed with an upper-case "N".
    3. Whatever 8-bit encoding is used, the "encoding" noted in the XML declaration must match the actual encoding of the bytes.
    4. The 8-bit encoding will be converted into UTF-16 LE by the XML datatype

With the points outlined above in mind, and given that strings in .NET are always UTF-16 LE / UCS-2 LE (there is no difference between those in terms of encoding), we can answer your questions:

Is there a reason why I shouldn't use StringWriter to serialize an Object when I need it as a string afterwards?

No, your StringWriter code appears to be just fine (at least I see no issues in my limited testing using the 2nd code block from the question).

Wouldn't setting the encoding to UTF-16 (in the xml tag) work then?

It isn't necessary to provide the XML declaration. When it is missing, the encoding is assumed to be UTF-16 LE if you pass the string into SQL Server as NVARCHAR (i.e. SqlDbType.NVarChar) or XML (i.e. SqlDbType.Xml). The encoding is assumed to be the default 8-bit Code Page if passing in as VARCHAR (i.e. SqlDbType.VarChar). If you have any non-standard-ASCII characters (i.e. values 128 and above) and are passing in as VARCHAR, then you will likely see "?" for BMP characters and "??" for Supplementary Characters as SQL Server will convert the UTF-16 string from .NET into an 8-bit string of the current Database's Code Page before converting it back into UTF-16 / UCS-2. But you shouldn't get any errors.

On the other hand, if you do specify the XML declaration, then you must pass into SQL Server using the matching 8-bit or 16-bit datatype. So if you have a declaration stating that the encoding is either UCS-2 or UTF-16, then you must pass in as SqlDbType.NVarChar or SqlDbType.Xml. Or, if you have a declaration stating that the encoding is one of the 8-bit options (i.e. UTF-8, Windows-1252, iso-8859-1, etc), then you must pass in as SqlDbType.VarChar. Failure to match the declared encoding with the proper 8 or 16 -bit SQL Server datatype will result in the "unable to switch the encoding" error that you were getting.

For example, using your StringWriter-based serialization code, I simply printed the resulting string of the XML and used it in SSMS. As you can see below, the XML declaration is included (because StringWriter does not have an option to OmitXmlDeclaration like XmlWriter does), which poses no problem so long as you pass the string in as the correct SQL Server datatype:

-- Upper-case "N" prefix == NVARCHAR, hence no error:
DECLARE @Xml XML = N'<?xml version="1.0" encoding="utf-16"?>
<string>Test ?</string>';
SELECT @Xml;
-- <string>Test ?</string>

As you can see, it even handles characters beyond standard ASCII, given that ? is BMP Code Point U+1234, and is Supplementary Character Code Point U+1F638. However, the following:

-- No upper-case "N" prefix on the string literal, hence VARCHAR:
DECLARE @Xml XML = '<?xml version="1.0" encoding="utf-16"?>
<string>Test ?</string>';

results in the following error:

Msg 9402, Level 16, State 1, Line XXXXX
XML parsing: line 1, character 39, unable to switch the encoding

Ergo, all of that explanation aside, the full solution to your original question is:

You were clearly passing the string in as SqlDbType.VarChar. Switch to SqlDbType.NVarChar and it will work without needing to go through the extra step of removing the XML declaration. This is preferred over keeping SqlDbType.VarChar and removing the XML declaration because this solution will prevent data loss when the XML includes non-standard-ASCII characters. For example:

-- No upper-case "N" prefix on the string literal == VARCHAR, and no XML declaration:
DECLARE @Xml2 XML = '<string>Test ?</string>';
SELECT @Xml2;
-- <string>Test ???</string>

As you can see, there is no error this time, but now there is data-loss 🙀.

curl_exec() always returns false

This happened to me yesterday and in my case was because I was following a PDF manual to develop some module to communicate with an API and while copying the link directly from the manual, for some odd reason, the hyphen from the copied link was in a different encoding and hence the curl_exec() was always returning false because it was unable to communicate with the server.

It took me a couple hours to finally understand the diference in the characters bellow:

https://www.e-example.com/api
https://www.e-example.com/api

Every time I tried to access the link directly from a browser it converted to something likehttps://www.xn--eexample-0m3d.com/api.

It may seem to you that they are equal but if you check the encoding of the hyphens here you'll see that the first hyphen is a unicode characters U+2010 and the other is a U+002D.

Hope this helps someone.

Inner join vs Where

No! The same execution plan, look at these two tables:

CREATE TABLE table1 (
  id INT,
  name VARCHAR(20)
);

CREATE TABLE table2 (
  id INT,
  name VARCHAR(20)
);

The execution plan for the query using the inner join:

-- with inner join

EXPLAIN PLAN FOR
SELECT * FROM table1 t1
INNER JOIN table2 t2 ON t1.id = t2.id;

SELECT *
FROM TABLE (DBMS_XPLAN.DISPLAY);

-- 0 select statement
-- 1 hash join (access("T1"."ID"="T2"."ID"))
-- 2 table access full table1
-- 3 table access full table2

And the execution plan for the query using a WHERE clause.

-- with where clause

EXPLAIN PLAN FOR
SELECT * FROM table1 t1, table2 t2
WHERE t1.id = t2.id;

SELECT *
FROM TABLE (DBMS_XPLAN.DISPLAY);

-- 0 select statement
-- 1 hash join (access("T1"."ID"="T2"."ID"))
-- 2 table access full table1
-- 3 table access full table2

How to check if an NSDictionary or NSMutableDictionary contains a key?

objectForKey will return nil if a key doesn't exist.

Subquery returned more than 1 value.This is not permitted when the subquery follows =,!=,<,<=,>,>= or when the subquery is used as an expression

You can use IN operator as below

select * from dbo.books where isbn IN
(select isbn from dbo.lending where lended_date between @fdate and @tdate)

Node: log in a file instead of the console

Straight from nodejs's API docs on Console

const output = fs.createWriteStream('./stdout.log');
const errorOutput = fs.createWriteStream('./stderr.log');
// custom simple logger
const logger = new Console(output, errorOutput);
// use it like console
const count = 5;
logger.log('count: %d', count);
// in stdout.log: count 5

Twitter Bootstrap 3, vertically center content

You can use display:inline-block instead of float and vertical-align:middle with this CSS:

.col-lg-4, .col-lg-8 {
    float:none;
    display:inline-block;
    vertical-align:middle;
    margin-right:-4px;
}

The demo http://bootply.com/94402

How to find a value in an array and remove it by using PHP array functions?

This solution is the combination of @Peter's solution for deleting multiple occurences and @chyno solution for removing first occurence. That's it what I'm using.

/**
 * @param array $haystack
 * @param mixed $value
 * @param bool $only_first
 * @return array
 */
function array_remove_values(array $haystack, $needle = null, $only_first = false)
{
    if (!is_bool($only_first)) { throw new Exception("The parameter 'only_first' must have type boolean."); }
    if (empty($haystack)) { return $haystack; }

    if ($only_first) { // remove the first found value
        if (($pos = array_search($needle, $haystack)) !== false) {
            unset($haystack[$pos]);
        }
    } else { // remove all occurences of 'needle'
        $haystack = array_diff($haystack, array($needle));
    }

    return $haystack;
}

Also have a look here: PHP array delete by value (not key)

Installing Git on Eclipse

Try with this link: http://download.eclipse.org/egit/github/updates

1)Go to Help-> Install new Software

2)Click on Add...

3)Name: eGit Location:http://download.eclipse.org/egit/github/updates

4)Click on OK

5)Accept the licence.

You are good to go

UIGestureRecognizer on UIImageView

I just done this with swift4 by adding 3 gestures together in single view

  1. UIPinchGestureRecognizer : Zoom in and zoom out view.
  2. UIRotationGestureRecognizer : Rotate the view.
  3. UIPanGestureRecognizer : Dragging the view.

Here my sample code

class ViewController: UIViewController: UIGestureRecognizerDelegate{
      //your image view that outlet from storyboard or xibs file.
     @IBOutlet weak var imgView: UIImageView!
     // declare gesture recognizer
     var panRecognizer: UIPanGestureRecognizer?
     var pinchRecognizer: UIPinchGestureRecognizer?
     var rotateRecognizer: UIRotationGestureRecognizer?

     override func viewDidLoad() {
          super.viewDidLoad()
          // Create gesture with target self(viewcontroller) and handler function.  
          self.panRecognizer = UIPanGestureRecognizer(target: self, action: #selector(self.handlePan(recognizer:)))
          self.pinchRecognizer = UIPinchGestureRecognizer(target: self, action: #selector(self.handlePinch(recognizer:)))
          self.rotateRecognizer = UIRotationGestureRecognizer(target: self, action: #selector(self.handleRotate(recognizer:)))
          //delegate gesture with UIGestureRecognizerDelegate
          pinchRecognizer?.delegate = self
          rotateRecognizer?.delegate = self
          panRecognizer?.delegate = self
          // than add gesture to imgView
          self.imgView.addGestureRecognizer(panRecognizer!)
          self.imgView.addGestureRecognizer(pinchRecognizer!)
          self.imgView.addGestureRecognizer(rotateRecognizer!)
     }

     // handle UIPanGestureRecognizer 
     @objc func handlePan(recognizer: UIPanGestureRecognizer) {    
          let gview = recognizer.view
          if recognizer.state == .began || recognizer.state == .changed {
               let translation = recognizer.translation(in: gview?.superview)
               gview?.center = CGPoint(x: (gview?.center.x)! + translation.x, y: (gview?.center.y)! + translation.y)
               recognizer.setTranslation(CGPoint.zero, in: gview?.superview)
          }
     }

     // handle UIPinchGestureRecognizer 
     @objc func handlePinch(recognizer: UIPinchGestureRecognizer) {
          if recognizer.state == .began || recognizer.state == .changed {
               recognizer.view?.transform = (recognizer.view?.transform.scaledBy(x: recognizer.scale, y: recognizer.scale))!
               recognizer.scale = 1.0
         }
     }   

     // handle UIRotationGestureRecognizer 
     @objc func handleRotate(recognizer: UIRotationGestureRecognizer) {
          if recognizer.state == .began || recognizer.state == .changed {
               recognizer.view?.transform = (recognizer.view?.transform.rotated(by: recognizer.rotation))!
               recognizer.rotation = 0.0
           }
     }

     // mark sure you override this function to make gestures work together 
     func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
         return true
     }

}

Any question, just type to comment. thank you

Fastest way to zero out a 2d array in C?

memset(array, 0, sizeof(int [n][n]));

ERROR: Sonar server 'http://localhost:9000' can not be reached

In sonar.properties file in conf folder I had hardcoaded ip of my machine where sobarqube was installed in property sonar.web.host=10.9 235.22 I commented this and it started working for me.

insert a NOT NULL column to an existing table

Other SQL implementations have similar restrictions. The reason is that adding a column requires adding values for that column (logically, even if not physically), which default to NULL. If you don't allow NULL, and don't have a default, what is the value going to be?

Since SQL Server supports ADD CONSTRAINT, I'd recommend Pavel's approach of creating a nullable column, and then adding a NOT NULL constraint after you've filled it with non-NULL values.

How change List<T> data to IQueryable<T> data

var list = new List<string>();
var queryable = list.AsQueryable();

Add a reference to: System.Linq

ClassCastException, casting Integer to Double

sum = Double.parseDouble(""+marks.get(i));

How to check if a character in a string is a digit or letter

You could use the existing methods from the Character class. Take a look at the docs:

http://download.java.net/jdk7/archive/b123/docs/api/java/lang/Character.html#isDigit(char)

So, you could do something like this...

String character = in.next();
char c = character.charAt(0);
...
if (Character.isDigit(c)) { 
    ... 
} else if (Character.isLetter(c)) {
    ...
}
...

If you ever want to know exactly how this is implemented, you could always look at the Java source code.

Debug assertion failed. C++ vector subscript out of range

this type of error usually occur when you try to access data through the index in which data data has not been assign. for example

//assign of data in to array
for(int i=0; i<10; i++){
   arr[i]=i;
}
//accessing of data through array index
for(int i=10; i>=0; i--){
cout << arr[i];
}

the code will give error (vector subscript out of range) because you are accessing the arr[10] which has not been assign yet.

Setting a system environment variable from a Windows batch file?

Simple example for how to set JAVA_HOME with setx.exe in command line:

setx JAVA_HOME "C:\Program Files (x86)\Java\jdk1.7.0_04"

This will set environment variable "JAVA_HOME" for current user. If you want to set a variable for all users, you have to use option "-m". Here is an example:

setx -m JAVA_HOME "C:\Program Files (x86)\Java\jdk1.7.0_04"

Note: you have to execute this command as Administrator.

Note: Make sure to run the command setx from an command-line Admin window

Get the client's IP address in socket.io

This seems to work:

var io = require('socket.io').listen(80);
io.sockets.on('connection', function (socket) {
  var endpoint = socket.manager.handshaken[socket.id].address;
  console.log('Client connected from: ' + endpoint.address + ":" + endpoint.port);
});

percentage of two int?

If you don't add .0f it will be treated like it is an integer, and an integer division is a lot different from a floating point division indeed :)

float percent = (n * 100.0f) / v;

If you need an integer out of this you can of course cast the float or the double again in integer.

int percent = (int)((n * 100.0f) / v);

If you know your n value is less than 21474836 (that is (2 ^ 31 / 100)), you can do all using integer operations.

int percent = (n * 100) / v;

If you get NaN is because wathever you do you cannot divide for zero of course... it doesn't make sense.

Convert double to BigDecimal and set BigDecimal Precision

You want to try String.format("%f", d), which will print your double in decimal notation. Don't use BigDecimal at all.

Regarding the precision issue: You are first storing 47.48 in the double c, then making a new BigDecimal from that double. The loss of precision is in assigning to c. You could do

BigDecimal b = new BigDecimal("47.48")

to avoid losing any precision.

python pandas extract year from datetime: df['year'] = df['date'].year is not working

What worked for me was upgrading pandas to latest version:

From Command Line do:

conda update pandas

How to wrap text of HTML button with fixed width?

white-space: normal;
word-wrap: break-word;

Mine works with both

Is there a standardized method to swap two variables in Python?

To get around the problems explained by eyquem, you could use the copy module to return a tuple containing (reversed) copies of the values, via a function:

from copy import copy

def swapper(x, y):
  return (copy(y), copy(x))

Same function as a lambda:

swapper = lambda x, y: (copy(y), copy(x))

Then, assign those to the desired names, like this:

x, y = swapper(y, x)

NOTE: if you wanted to you could import/use deepcopy instead of copy.

C Program to find day of week given date

Here is a simple code that I created in c that should fix your problem :

#include <conio.h>

int main()
{
  int y,n,oy,ly,td,a,month,mon_,d,days,down,up; // oy==ordinary year, td=total days, d=date

    printf("Enter the year,month,date: ");
    scanf("%d%d%d",&y,&month,&d);
    n= y-1; //here we subtracted one year because we have to find on a particular day of that year, so we will not count whole year.
    oy= n%4;

    if(oy==0) // for leap year
      {
         mon_= month-1;
         down= mon_/2;  //down means months containing 30 days.
           up= mon_-down; // up means months containing 31 days.
           if(mon_>=2)
             {
               days=(up*31)+((down-1)*30)+29+d; // here in down case one month will be of feb so we subtracted 1 and after that seperately
               td= (oy*365)+(ly*366)+days;      // added 29 days as it is the if block of leap year case.
             }
           if(mon_==1)
             {
               days=(up*31)+d;
               td= (oy*365)+(ly*366)+days;
             } 
           if(mon_==0)
             {
               days= d;
               td= (oy*365)+(ly*366)+days;
             }    
      }
    else
      {
         mon_= month-1;
         down= mon_/2;
           up= mon_-down;
           if(mon_>=2)
             {
               days=(up*31)+((down-1)*30)+28+d;
               td= (oy*365)+(ly*366)+days;
             }
           if(mon_==1)
             {
               days=(up*31)+d;
               td= (oy*365)+(ly*366)+days;
             } 
           if(mon_==0)
             {
               days= d;
               td= (oy*365)+(ly*366)+days;
             }    
      }  

    ly= n/4;
     a= td%7;

     if(a==0)
       printf("\nSunday");
     if(a==1)
       printf("\nMonday");
     if(a==2)
       printf("\nTuesday");
     if(a==3)
       printf("\nWednesday");
     if(a==4)
       printf("\nThursday");
     if(a==5)
       printf("\nFriday");
     if(a==6)
       printf("\nSaturday");
  return 0;   
}

Download multiple files with a single action

HTTP does not support more than one file download at once.

There are two solutions:

  • Open x amount of windows to initiate the file downloads (this would be done with JavaScript)
  • preferred solution create a script to zip the files

Where do I find some good examples for DDD?

Code Camp Server, Jeffrey Palermo's sample code for the book ASP.NET MVC in Action. While the book is focused on the presentation layer, the application is modeled using DDD.

What are WSDL, SOAP and REST?

A WSDL document describes a webservice. It specifies the location of the service and the methods of the service using these major elements: data types using in webservice data elements for each operation describe the operations that can be performed and the messages envolved

SOAP (Simple Object Access Protocol) is a messaging protocol that allows programs that run on disparate operating systems to communicate using http and xml.

ReDim Preserve to a Multi-Dimensional Array in Visual Basic 6

Easiest way to do this in VBA is to create a function that takes in an array, your new amount of rows, and new amount of columns.

Run the below function to copy in all of the old data back to the array after it has been resized.

 function dynamic_preserve(array1, num_rows, num_cols)

        dim array2 as variant

        array2 = array1

        reDim array1(1 to num_rows, 1 to num_cols)

        for i = lbound(array2, 1) to ubound(array2, 2)

               for j = lbound(array2,2) to ubound(array2,2)

                      array1(i,j) = array2(i,j)

               next j

        next i

        dynamic_preserve = array1

end function

After installation of Gulp: “no command 'gulp' found”

I solved the issue removing gulp and installing gulp-cli again:

rm /usr/local/bin/gulp
npm install -g gulp-cli

How to install PyQt5 on Windows?

First try this in your Windows cmd window:

pip3 install pyqt5

If that is successful, it will look something like this:

C:\Windows\System32>pip3 install pyqt5
Collecting pyqt5
  Downloading PyQt5-5.9-5.9.1-cp35.cp36.cp37-none-win_amd64.whl (77.2MB)
    100% |################################| 77.2MB 13kB/s
Collecting sip<4.20,>=4.19.3 (from pyqt5)
  Downloading sip-4.19.3-cp35-none-win_amd64.whl (49kB)
    100% |################################| 51kB 984kB/s
Installing collected packages: sip, pyqt5
Successfully installed pyqt5-5.9 sip-4.19.3

If that did not work, you might try this link from SourceForge.

PyQt5 .exe installers for Windows

How to find the installer that's right for you?

First, determine what version of Python you have and whether you have 32-bit or 64-bit Python. Next, open one of the directories. I'm on Python 3.5 64-bit so I'm looking for a .exe with those specs. When you open a directory on SourceForge, you will see some directories with ONLY .zip or .tar.gz. That's not what you're looking for. A good indication of which directory you should click is given by the "Downloads/Week" column. I'll open the PyQt-5.6 directory in my case.

Here we notice some .exe files:

PyQt-5.6
|_PyQt5-5.6-gpl-Py3.5-Qt5.6.0-x32-2.exe
|_PyQt5-5.6-gpl-Py3.5-Qt5.6.0-x64-2.exe
|_PyQt5_gpl-5.6.zip
|_PyQt5_gpl-5.6.tar.gz

I know these are Python 3.5 by Py3.5 in the file name. I am also looking for the 64-bit version so I'll download PyQt5-5.6-gpl-Py3.5-Qt5.6.0-x64-2.exe. Final answer!

Note: if you try to install a version that's not compatible with your system, a dialog box will appear immediately after running the .exe. That's an indication that you've chosen the wrong one. I'm not trying to sound like a dbag... I did that several times!

To test a successful install, in your Python interpreter, try to import:

from PyQt5 import QtCore, QtGui, QtWidgets

Convert UTC datetime string to local datetime

This answer should be helpful if you don't want to use any other modules besides datetime.

datetime.utcfromtimestamp(timestamp) returns a naive datetime object (not an aware one). Aware ones are timezone aware, and naive are not. You want an aware one if you want to convert between timezones (e.g. between UTC and local time).

If you aren't the one instantiating the date to start with, but you can still create a naive datetime object in UTC time, you might want to try this Python 3.x code to convert it:

import datetime

d=datetime.datetime.strptime("2011-01-21 02:37:21", "%Y-%m-%d %H:%M:%S") #Get your naive datetime object
d=d.replace(tzinfo=datetime.timezone.utc) #Convert it to an aware datetime object in UTC time.
d=d.astimezone() #Convert it to your local timezone (still aware)
print(d.strftime("%d %b %Y (%I:%M:%S:%f %p) %Z")) #Print it with a directive of choice

Be careful not to mistakenly assume that if your timezone is currently MDT that daylight savings doesn't work with the above code since it prints MST. You'll note that if you change the month to August, it'll print MDT.

Another easy way to get an aware datetime object (also in Python 3.x) is to create it with a timezone specified to start with. Here's an example, using UTC:

import datetime, sys

aware_utc_dt_obj=datetime.datetime.now(datetime.timezone.utc) #create an aware datetime object
dt_obj_local=aware_utc_dt_obj.astimezone() #convert it to local time

#The following section is just code for a directive I made that I liked.
if sys.platform=="win32":
    directive="%#d %b %Y (%#I:%M:%S:%f %p) %Z"
else:
    directive="%-d %b %Y (%-I:%M:%S:%f %p) %Z"

print(dt_obj_local.strftime(directive))

If you use Python 2.x, you'll probably have to subclass datetime.tzinfo and use that to help you create an aware datetime object, since datetime.timezone doesn't exist in Python 2.x.

JNZ & CMP Assembly Instructions

I will make a little bit wider answer here.

There are generally speaking two types of conditional jumps in x86:

  1. Arithmetic jumps - like JZ (jump if zero), JC (jump if carry), JNC (jump if not carry), etc.

  2. Comparison jumps - JE (jump if equal), JB (jump if below), JAE (jump if above or equal), etc.

So, use the first type only after arithmetic or logical instructions:

sub  eax, ebx
jnz  .result_is_not_zero 

and  ecx, edx
jz   .the_bit_is_not_set

Use the second group only after CMP instructions:

cmp  eax, ebx
jne  .eax_is_not_equal_to_ebx

cmp  ecx, edx
ja   .ecx_is_above_than_edx

This way, the program becomes more readable and you will never be confused.

Note, that sometimes these instructions are actually synonyms. JZ == JE; JC == JB; JNC == JAE and so on. The full table is following. As you can see, there are only 16 conditional jump instructions, but 30 mnemonics - they are provided to allow creation of more readable source code:

Mnemonic        Condition tested  Description  

jo              OF = 1            overflow 
jno             OF = 0            not overflow 
jc, jb, jnae    CF = 1            carry / below / not above nor equal
jnc, jae, jnb   CF = 0            not carry / above or equal / not below
je, jz          ZF = 1            equal / zero
jne, jnz        ZF = 0            not equal / not zero
jbe, jna        CF or ZF = 1      below or equal / not above
ja, jnbe        CF and ZF = 0      above / not below or equal
js              SF = 1            sign 
jns             SF = 0            not sign 
jp, jpe         PF = 1            parity / parity even 
jnp, jpo        PF = 0            not parity / parity odd 
jl, jnge        SF xor OF = 1     less / not greater nor equal
jge, jnl        SF xor OF = 0     greater or equal / not less
jle, jng    (SF xor OF) or ZF = 1 less or equal / not greater
jg, jnle    (SF xor OF) or ZF = 0 greater / not less nor equal 

getting only name of the class Class.getName()

Social.class.getSimpleName()

getSimpleName() : Returns the simple name of the underlying class as given in the source code. Returns an empty string if the underlying class is anonymous. The simple name of an array is the simple name of the component type with "[]" appended. In particular the simple name of an array whose component type is anonymous is "[]".

Is it possible to modify a registry entry via a .bat/.cmd script?

In addition to reg.exe, I highly recommend that you also check out powershell, its vastly more capable in its registry handling.

How to convert local time string to UTC?

In python3:

pip install python-dateutil

from dateutil.parser import tz

mydt.astimezone(tz.gettz('UTC')).replace(tzinfo=None) 

High Quality Image Scaling Library

There's an article on Code Project about using GDI+ for .NET to do photo resizing using, say, Bicubic interpolation.

There was also another article about this topic on another blog (MS employee, I think), but I can't find the link anywhere. :( Perhaps someone else can find it?

CSS Equivalent of the "if" statement

Changing your css file to a scss file would allow you to do the trick. An example in Angular would be to use an ngClass and your scss would look like:

 .sidebar {
    height: 100%;
    width: 60px;

    &.is-open {
        width: 150px
    }
} 

Checking whether the pip is installed?

If you are on a linux machine running Python 2 you can run this commands:

1st make sure python 2 is installed:

python2 --version

2nd check to see if pip is installed:

pip --version

If you are running Python 3 you can run this command:

1st make sure python 3 is installed:

python3 --version

2nd check to see if pip3 is installed:

pip3 --version

If you do not have pip installed you can run these commands to install pip (it is recommended you install pip for Python 2 and Python 3):

Install pip for Python 2:

sudo apt install python-pip

Then verify if it is installed correctly:

pip --version

Install pip for Python 3:

sudo apt install python3-pip

Then verify if it is installed correctly:

pip3 --version

For more info see: https://itsfoss.com/install-pip-ubuntu/

UPDATE I would like to mention a few things. When working with Django I learned that my Linux install requires me to use python 2.7, so switching my default python version for the python and pip command alias's to python 3 with alias python=python3 is not recommended. Therefore I use the python3 and pip3 commands when installing software like Django 3.0, which works better with Python 3. And I keep their alias's pointed towards whatever Python 3 version I want like so alias python3=python3.8.

Keep In Mind When you are going to use your package in the future you will want to use the pip or pip3 command depending on which one you used to initially install the package. So for example if I wanted to change my change my Django package version I would use the pip3 command and not pip like so, pip3 install Django==3.0.11.

Notice When running checking the packages version for python: $ python -m django --version and python3: $ python3 -m django --version, two different versions of django will show because I installed django v3.0.11 with pip3 and django v1.11.29 with pip.

Image, saved to sdcard, doesn't appear in Android's Gallery app

this work with me

File file = ..... // Save file

context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.fromFile(file)));

How is Java platform-independent when it needs a JVM to run?

JVM will be platform dependent.
But whatever it will generate that will be platform independent. [which we called as bytecode or simply you can say...the class file]. for that why Java is called Platform independent.
you can run the same class file on Mac as well on Windows but it will require JRE.

Preserve line breaks in angularjs

Well it depends, if you want to bind datas, there shouldn't be any formatting in it, otherwise you can bind-html and do description.replace(/\\n/g, '<br>') not sure it's what you want though.

On npm install: Unhandled rejection Error: EACCES: permission denied

change ownership

sudo chown -R $USER:$GROUP ~/.npm
sudo chown -R $USER:$GROUP ~/.config 

worked for as i installed package using sudo

How to use paths in tsconfig.json?

It looks like there has been an update to React that doesn't allow you to set the "paths" in the tsconfig.json anylonger.

Nicely React just outputs a warning:

The following changes are being made to your tsconfig.json file:
  - compilerOptions.paths must not be set (aliased imports are not supported)

then updates your tsconfig.json and removes the entire "paths" section for you. There is a way to get around this run

npm run eject

This will eject all of the create-react-scripts settings by adding config and scripts directories and build/config files into your project. This also allows a lot more control over how everything is built, named etc. by updating the {project}/config/* files.

Then update your tsconfig.json

{
    "compilerOptions": {
        "baseUrl": "./src",
        {…}
        "paths": {
            "assets/*": [ "assets/*" ],
            "styles/*": [ "styles/*" ]
        }
    },
}

LINQ Inner-Join vs Left-Join

If you actually have a database, this is the most-simple way:

var lsPetOwners = ( from person in context.People
                    from pets in context.Pets
                        .Where(mypet => mypet.Owner == person.ID) 
                        .DefaultIfEmpty()
                     select new { OwnerName = person.Name, Pet = pets.Name }
                   ).ToList();

json_decode() expects parameter 1 to be string, array given

Set decoding to true

Your decoding is not set to true. If you don't have access to set the source to true. The code below will fix it for you.

$WorkingArray = json_decode(json_encode($data),true);

How to return dictionary keys as a list in Python?

A bit off on the "duck typing" definition -- dict.keys() returns an iterable object, not a list-like object. It will work anywhere an iterable will work -- not any place a list will. a list is also an iterable, but an iterable is NOT a list (or sequence...)

In real use-cases, the most common thing to do with the keys in a dict is to iterate through them, so this makes sense. And if you do need them as a list you can call list().

Very similarly for zip() -- in the vast majority of cases, it is iterated through -- why create an entire new list of tuples just to iterate through it and then throw it away again?

This is part of a large trend in python to use more iterators (and generators), rather than copies of lists all over the place.

dict.keys() should work with comprehensions, though -- check carefully for typos or something... it works fine for me:

>>> d = dict(zip(['Sounder V Depth, F', 'Vessel Latitude, Degrees-Minutes'], [None, None]))
>>> [key.split(", ") for key in d.keys()]
[['Sounder V Depth', 'F'], ['Vessel Latitude', 'Degrees-Minutes']]

Shell script current directory?

To print the current working Directory i.e. pwd just type command like:

echo "the PWD is : ${pwd}"

Assign width to half available screen width declaratively

<LinearLayout 
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView
    android:id="@+id/textD_Author"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="20dp"
    android:text="Author : "
    android:textColor="#0404B4"
    android:textSize="20sp" />
 <TextView
    android:id="@+id/textD_Tag"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="20dp"
    android:text="Edition : "
    android:textColor="#0404B4"
    android:textSize="20sp" />
<LinearLayout
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="horizontal"
    android:weightSum="1" >
    <Button
        android:id="@+id/btbEdit"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="0.5"
        android:text="Edit" />
    <Button
        android:id="@+id/btnDelete"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="0.5"
        android:text="Delete" />
</LinearLayout>
</LinearLayout>

Turn off warnings and errors on PHP and MySQL

When you are sure your script is perfectly working, you can get rid of warning and notices like this: Put this line at the beginning of your PHP script:

error_reporting(E_ERROR);

Before that, when working on your script, I would advise you to properly debug your script so that all notice or warning disappear one by one.

So you should first set it as verbose as possible with:

error_reporting(E_ERROR | E_WARNING | E_PARSE | E_NOTICE);

UPDATE: how to log errors instead of displaying them

As suggested in the comments, the better solution is to log errors into a file so only the PHP developer sees the error messages, not the users.

A possible implementation is via the .htaccess file, useful if you don't have access to the php.ini file (source).

# Suppress PHP errors
php_flag display_startup_errors off
php_flag display_errors off
php_flag html_errors off
php_value docref_root 0
php_value docref_ext 0

# Enable PHP error logging
php_flag  log_errors on
php_value error_log  /home/path/public_html/domain/PHP_errors.log

# Prevent access to PHP error log
<Files PHP_errors.log>
 Order allow,deny
 Deny from all
 Satisfy All
</Files>

How to redirect DNS to different ports

(It's been a while since I did this stuff. Please don't blindly assume that all the details below are correct. But I hope I'm not too embarrassingly wrong. :))


As the previous answer stated, the Minecraft client (as of 1.3.1) supports SRV record lookup using the service name _minecraft and the protocol name _tcp, which means that if your zone file looks like this...

arboristal.com.                 86400 IN A   <your IP address>
_minecraft._tcp.arboristal.com. 86400 IN SRV 10 20 25565 arboristal.com.
_minecraft._tcp.arboristal.com. 86400 IN SRV 10 40 25566 arboristal.com.
_minecraft._tcp.arboristal.com. 86400 IN SRV 10 40 25567 arboristal.com.

...then Minecraft clients who perform SRV record lookup as hinted in the changelog will use ports 25566 and 25567 with preference (40% of the time each) over port 25565 (20% of the time). We can assume that Minecraft clients who do not find and respect these SRV records will use port 25565 as usual.


However, I would argue that it would actually be more "clean and professional" to do it using a load balancer such as Nginx. (I pick Nginx just because I've used it before. I'm not claiming it's uniquely suited to this task. It might even be a bad choice for some reason.) Then you don't have to mess with your DNS, and you can use the same approach to load-balance any service, not just ones like Minecraft which happen to have done the hard client-side work to look up and respect SRV records. To do it the Nginx way, you'd run Nginx on the arboristal.com machine with something like the following in /etc/nginx/sites-enabled/arboristal.com:

upstream minecraft_servers {
    ip_hash;
    server 127.0.0.1:25566 weight=1;
    server 127.0.0.1:25567 weight=1;
    server 127.0.0.1:25568 weight=1;
}
server {
    listen 25565;
    proxy_pass minecraft_servers;
}

Here we are controlling the load-balancing ourselves on the server side (via Nginx), so we no longer need to worry that badly behaved clients might prefer port 25565 to the other two ports. In fact, now all clients will talk to arboristal.com:25565! But the listener on that port is no longer a Minecraft server; it's Nginx, secretly proxying all the traffic onto three other ports on the same machine.

We load-balance based on a hash of the client's IP address (ip_hash), so that if a client disconnects and then reconnects later, there's a good chance that it'll get reconnected to the same Minecraft server it had before. (I don't know how much this matters to Minecraft, or how SRV-enabled clients are programmed to deal with this aspect.)

Notice that we used to run a Minecraft server on port 25565; I've moved it to port 25568 so that we can use port 25565 for the load-balancer.

A possible disadvantage of the Nginx method is that it makes Nginx a bottleneck in your system. If Nginx goes down, then all three servers become unreachable. If some part of your system can't keep up with the volume of traffic on that single port, 25565, all three servers become flaky. And not to mention, Nginx is a big new dependency in your ecosystem. Maybe you don't want to introduce yet another massive piece of software with a complicated config language and a huge attack surface. I can respect that.

A possible advantage of the Nginx method is... that it makes Nginx a bottleneck in your system! You can apply global policies via Nginx, such as rejecting packets above a certain size, or responding with a static web page to HTTP connections on port 80. You can also firewall off ports 25566, 25567, and 25568 from the Internet, since now they should be talked to only by Nginx over the loopback interface. This reduces your attack surface somewhat.

Nginx also makes it easier to add new Minecraft servers to your backend; now you can just add a server line to your config and service nginx reload. Using the old port-based approach, you'd have to add a new SRV record with your DNS provider (and it could take up to 86400 seconds for clients to notice the change) and then also remember to edit your firewall (e.g. /etc/iptables.rules) to permit external traffic over that new port.

Nginx also frees you from having to think about DNS TTLs when making ops changes. Suppose you decide to split up your three Minecraft servers onto three different physical machines with different IP addresses. Using Nginx, you can do that completely via config changes to your server lines, and you can keep those new machines inside your firewall (connected only to Nginx over a private interface), and the changes will take effect immediately, by definition. Whereas, using SRV records, you'll have to rewrite your zone file to something like this...

arboristal.com.                 86400 IN CNAME mc1.arboristal.com.
mc1.arboristal.com.             86400 IN A   <a new machine's IP address>
mc2.arboristal.com.             86400 IN A   <a new machine's IP address>
mc3.arboristal.com.             86400 IN A   <a new machine's IP address>
_minecraft._tcp.arboristal.com. 86400 IN SRV 10 20 25565 mc1.arboristal.com.
_minecraft._tcp.arboristal.com. 86400 IN SRV 10 40 25565 mc2.arboristal.com.
_minecraft._tcp.arboristal.com. 86400 IN SRV 10 40 25565 mc3.arboristal.com.

...and you'll have to leave all three new machines poking outside your firewall so that they can receive connections from the Internet. And you'll have to wait up to 86400 seconds for your clients to notice the change, which could affect the complexity of your rollout plan. And if you were running any other services (such as an HTTP server) on arboristal.com, now you have to move them to the mc1.arboristal.com machine because of how I did that CNAME. I did that only for the benefit of those hypothetical Minecraft clients who don't respect SRV records and will still be trying to connect to arboristal.com:25565.


So, I think both ways (SRV records and Nginx load-balancing) are reasonable, and your choice will depend on your personal preferences. I caricature the options as:

  • SRV records: "I just need it to work. I don't want complexity. And I know and trust my DNS provider."
  • Nginx: "I foresee arboristal.com taking over the world, or at least moving to a bigger machine someday. I'm not scared of learning a new tool. What's a zone file?"

How to set JAVA_HOME for multiple Tomcat instances?

Also, note that there shouldn't be any space after =:

set JAVA_HOME=C:\Program Files\Java\jdk1.6.0_27

ActionController::InvalidAuthenticityToken

This happened to me when carrying out manual tests of the sign up process of my application (signing up/in with multiple users).

A very simple and pragmatic solution may be to do what I did, and use a different browser (or incognito if using chrome).

This was a much better solution in my case than disabling security features!!

SQL SERVER: Get total days between two dates

DECLARE @FDate DATETIME='05-05-2019' /*This is first date*/
 GETDATE()/*This is Current date*/
SELECT (DATEDIFF(DAY,(@LastDate),GETDATE())) As DifferenceDays/*this query will return no of days between firstdate & Current date*/

Repair all tables in one go

Use following query to print REPAIR SQL statments for all tables inside a database:

select concat('REPAIR TABLE ', table_name, ';') from information_schema.tables 
where table_schema='mydatabase'; 

After that copy all the queries and execute it on mydatabase.

Note: replace mydatabase with desired DB name

HTML5 Video autoplay on iPhone

Here is the little hack to overcome all the struggles you have for video autoplay in a website:

  1. Check video is playing or not.
  2. Trigger video play on event like body click or touch.

Note: Some browsers don't let videos to autoplay unless the user interacts with the device.

So scripts to check whether video is playing is:

Object.defineProperty(HTMLMediaElement.prototype, 'playing', {
get: function () {
    return !!(this.currentTime > 0 && !this.paused && !this.ended && this.readyState > 2);
}});

And then you can simply autoplay the video by attaching event listeners to the body:

$('body').on('click touchstart', function () {
        const videoElement = document.getElementById('home_video');
        if (videoElement.playing) {
            // video is already playing so do nothing
        }
        else {
            // video is not playing
            // so play video now
            videoElement.play();
        }
});

Note: autoplay attribute is very basic which needs to be added to the video tag already other than these scripts.

You can see the working example with code here at this link:

How to autoplay video when the device is in low power mode / data saving mode / safari browser issue

Simple PHP form: Attachment to email (code golf)

PEAR::Mail_Mime? Sure, PEAR dependency of (min) 2 files (just mail_mime itself if you edit it to remove the pear dependencies), but it works well. Additionally, most servers have PEAR installed to some extent, and in the best cases they have Pear/Mail and Pear/Mail_Mime. Something that cannot be said for most other libraries offering the same functionality.

You may also consider looking in to PHP's IMAP extension. It's a little more complicated, and requires more setup (not enabled or installed by default), but is must more efficient at compilng and sending messages to an IMAP capable server.

startActivityForResult() from a Fragment and finishing child Activity, doesn't call onActivityResult() in Fragment

We could call startActivityForResult() directly from Fragment So You should call this.startActivityForResult(i, 1); instead of getActivity().startActivityForResult(i, 1);

Intent i = new Intent(getActivity(), SecondActivity.class);
i.putExtra("helloString", helloString);
this.startActivityForResult(i, 1);

Activity will send the Activity Result to your Fragment.

Way to run Excel macros from command line or batch file?

The method shown below allows to run defined Excel macro from batch file, it uses environment variable to pass macro name from batch to Excel.

Put this code to the batch file (use your paths to EXCEL.EXE and to the workbook):

Set MacroName=MyMacro
"C:\Program Files\Microsoft Office\Office15\EXCEL.EXE" "C:\MyWorkbook.xlsm"

Put this code to Excel VBA ThisWorkBook Object:

Private Sub Workbook_Open()
    Dim strMacroName As String
    strMacroName = CreateObject("WScript.Shell").Environment("process").Item("MacroName")
    If strMacroName <> "" Then Run strMacroName
End Sub

And put your code to Excel VBA Module, like as follows:

Sub MyMacro()
    MsgBox "MyMacro is running..."
End Sub

Launch the batch file and get the result:

macro's dialog

For the case when you don't intend to run any macro just put empty value Set MacroName= to the batch.

Add custom buttons on Slick Carousel

That's because they use an icon font for the buttons. They use "Slick" font as you can see in this image:

enter image description here

Basically, the make the letter "A" the form of an icon, the letter "B" the form of another one and so on.

For example:

enter image description here

If you want to know more about icon fonts click here

If you want to change the icons, you need to replace the whole button code or you can go to www.fontastic.me and create your own icon font. After that, replace the font file for the current one and you'll have your own icon.

How do I change the background color of the ActionBar of an ActionBarActivity using XML?

Behavior of Actionbar can also be changed in APIs < 11

See the Android Official Documentation for reference

I am building an app with minSdkVersion = "9" and targetSdkVersion = "21" I changed the color of action bar and it works fine with API level 9

Here is an xml

res/values/themes.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <!-- the theme applied to the application or activity -->
    <style name="CustomActionBarTheme"
           parent="@style/Theme.AppCompat.Light.DarkActionBar">
        <item name="android:actionBarStyle">@style/MyActionBar</item>

        <!-- Support library compatibility -->
        <item name="actionBarStyle">@style/MyActionBar</item>
    </style>

    <!-- ActionBar styles -->
    <style name="MyActionBar"
           parent="@style/Widget.AppCompat.Light.ActionBar.Solid.Inverse">
        <item name="android:background">@color/actionbar_background</item>

        <!-- Support library compatibility -->
        <item name="background">@color/actionbar_background</item>
    </style>
</resources>

and set the color of actionbar you want

res/values/colors.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="actionbar_background">#fff</color> //write the color you want here
</resources>

Actionbar color can also be defined in .class file, the snippet is

ActionBar bar = getActionBar();
bar.setBackgroundDrawable(new ColorDrawable(Color.parseColor("#0000ff")));

but this will not work with the API < 11, so styling the actionbar in xml is only way for API < 11

How can I list ALL DNS records?

Many DNS servers refuse ‘ANY’ queries. So the only way is to query for every type individually. Luckily there are sites that make this simpler. For example, https://www.nslookup.io shows the most popular record types by default, and has support for all existing record types.

selectOneMenu ajax events

Be carefull that the page does not contain any empty component which has "required" attribute as "true" before your selectOneMenu component running.
If you use a component such as

<p:inputText label="Nm:" id="id_name" value="#{ myHelper.name}" required="true"/>

then,

<p:selectOneMenu .....></p:selectOneMenu>

and forget to fill the required component, ajax listener of selectoneMenu cannot be executed.

Where can I find my Facebook application id and secret key?

I had a hard time finding where it is so here the image depicting it in 2019.  the location of app secret and app id in 2019.

How to see an HTML page on Github as a normal rendered HTML page to see preview in browser, without downloading?

Also, if you use Tampermonkey, you can add a script that will add preview with http://htmlpreview.github.com/ button into actions menu beside 'raw', 'blame' and 'history' buttons.

Script like this one: https://gist.github.com/vanyakosmos/83ba165b288af32cf85e2cac8f02ce6d

Server unable to read htaccess file, denying access to be safe

Set group of your public directory to nobody.