Programs & Examples On #Dhtml

Dynamic HTML, or DHTML, is an umbrella term for a collection of technologies used together to create interactive and animated web sites by using a combination of a static markup language (such as HTML), a client-side scripting language (such as JavaScript), a presentation definition language (such as CSS), and the Document Object Model.

Child element click event trigger the parent click event

The stopPropagation() method stops the bubbling of an event to parent elements, preventing any parent handlers from being notified of the event.

You can use the method event.isPropagationStopped() to know whether this method was ever called (on that event object).

Syntax:

Here is the simple syntax to use this method:

event.stopPropagation() 

Example:

$("div").click(function(event) {
    alert("This is : " + $(this).prop('id'));

    // Comment the following to see the difference
    event.stopPropagation();
});?

Set content of HTML <span> with Javascript

To do it without using a JavaScript library such as jQuery, you'd do it like this:

var span = document.getElementById("myspan"),
    text = document.createTextNode(''+intValue);
span.innerHTML = ''; // clear existing
span.appendChild(text);

If you do want to use jQuery, it's just this:

$("#myspan").text(''+intValue);

How do I programmatically click on an element in JavaScript?

Using jQuery you can do exactly the same thing, for example:

$("a").click();

Which will "click" all anchors on the page.

Getting all selected checkboxes in an array

ES6 version:

const values = Array
  .from(document.querySelectorAll('input[type="checkbox"]'))
  .filter((checkbox) => checkbox.checked)
  .map((checkbox) => checkbox.value);

_x000D_
_x000D_
function getCheckedValues() {_x000D_
  return Array.from(document.querySelectorAll('input[type="checkbox"]'))_x000D_
  .filter((checkbox) => checkbox.checked)_x000D_
  .map((checkbox) => checkbox.value);_x000D_
}_x000D_
_x000D_
const resultEl = document.getElementById('result');_x000D_
_x000D_
document.getElementById('showResult').addEventListener('click', () => {_x000D_
  resultEl.innerHTML = getCheckedValues();_x000D_
});
_x000D_
<input type="checkbox" name="type" value="1" />1_x000D_
<input type="checkbox" name="type" value="2" />2_x000D_
<input type="checkbox" name="type" value="3" />3_x000D_
<input type="checkbox" name="type" value="4" />4_x000D_
<input type="checkbox" name="type" value="5" />5_x000D_
_x000D_
<br><br>_x000D_
<button id="showResult">Show checked values</button>_x000D_
<br><br>_x000D_
<div id="result"></div>
_x000D_
_x000D_
_x000D_

How do I attach events to dynamic HTML elements with jQuery?

Binds a handler to an event (like click) for all current - and future - matched element. Can also bind custom events.

link text

$(function(){
    $(".myclass").live("click", function() {
        // do something
    });
});

What is the best JavaScript code to create an img element

var img = new Image(1,1); // width, height values are optional params 
img.src = 'http://www.testtrackinglink.com';

How to load up CSS files using Javascript?

Use this code:

var element = document.createElement("link");
element.setAttribute("rel", "stylesheet");
element.setAttribute("type", "text/css");
element.setAttribute("href", "external.css");
document.getElementsByTagName("head")[0].appendChild(element);

Redirect parent window from an iframe action

For current page - window.location.href = "Your url here";

For Parent page - window.top.location.href = "Your url here";

From HTML

<a href="http://someurl" target="_top">link</a>

How do I retrieve an HTML element's actual width and height?

Use width param as follows:

   style={{
      width: "80%",
      paddingLeft: 100,
      paddingRight: 200,
      paddingTop: 30,
      paddingBottom: 30,
      border: "3px solid lightGray",
    }}

jQuery document.createElement equivalent?

Here's your example in the "one" line.

this.$OuterDiv = $('<div></div>')
    .hide()
    .append($('<table></table>')
        .attr({ cellSpacing : 0 })
        .addClass("text")
    )
;

Update: I thought I'd update this post since it still gets quite a bit of traffic. In the comments below there's some discussion about $("<div>") vs $("<div></div>") vs $(document.createElement('div')) as a way of creating new elements, and which is "best".

I put together a small benchmark, and here are roughly the results of repeating the above options 100,000 times:

jQuery 1.4, 1.5, 1.6

               Chrome 11  Firefox 4   IE9
<div>            440ms      640ms    460ms
<div></div>      420ms      650ms    480ms
createElement    100ms      180ms    300ms

jQuery 1.3

                Chrome 11
<div>             770ms
<div></div>      3800ms
createElement     100ms

jQuery 1.2

                Chrome 11
<div>            3500ms
<div></div>      3500ms
createElement     100ms

I think it's no big surprise, but document.createElement is the fastest method. Of course, before you go off and start refactoring your entire codebase, remember that the differences we're talking about here (in all but the archaic versions of jQuery) equate to about an extra 3 milliseconds per thousand elements.


Update 2

Updated for jQuery 1.7.2 and put the benchmark on JSBen.ch which is probably a bit more scientific than my primitive benchmarks, plus it can be crowdsourced now!

http://jsben.ch/#/ARUtz

Modifying a query string without reloading the page

If you are looking for Hash modification, your solution works ok. However, if you want to change the query, you can use the pushState, as you said. Here it is an example that might help you to implement it properly. I tested and it worked fine:

if (history.pushState) {
    var newurl = window.location.protocol + "//" + window.location.host + window.location.pathname + '?myNewUrlQuery=1';
    window.history.pushState({path:newurl},'',newurl);
}

It does not reload the page, but it only allows you to change the URL query. You would not be able to change the protocol or the host values. And of course that it requires modern browsers that can process HTML5 History API.

For more information:

http://diveintohtml5.info/history.html

https://developer.mozilla.org/en-US/docs/Web/Guide/API/DOM/Manipulating_the_browser_history

Print <div id="printarea"></div> only?

This works well:

<style type="text/css">
@media print
{
body * { visibility: hidden; }
#printcontent * { visibility: visible; }
#printcontent { position: absolute; top: 40px; left: 30px; }
}
</style>

Note that this only works with "visibility". "display" won't do it. Tested in FF3.

How to resize html canvas element?

I just had the same problem as you, but found out about the toDataURL method, which proved useful.

The gist of it is to turn your current canvas into a dataURL, change your canvas size, and then draw what you had back into your canvas from the dataURL you saved.

So here's my code:

var oldCanvas = canvas.toDataURL("image/png");
var img = new Image();
img.src = oldCanvas;
img.onload = function (){
    canvas.height += 100;
    ctx.drawImage(img, 0, 0);
}

jQuery get the id/value of <li> element after click function

you can get the value of the respective li by using this method after click

HTML:-

<!DOCTYPE html>
<html>
<head>
    <title>show the value of li</title>
    <link rel="stylesheet"  href="pathnameofcss">
</head>
<body>

    <div id="user"></div>


    <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
    <ul id="pageno">
    <li value="1">1</li>
    <li value="2">2</li>
    <li value="3">3</li>
    <li value="4">4</li>
    <li value="5">5</li>
    <li value="6">6</li>
    <li value="7">7</li>
    <li value="8">8</li>
    <li value="9">9</li>
    <li value="10">10</li>

    </ul>

    <script src="pathnameofjs" type="text/javascript"></script>
</body>
</html>

JS:-

$("li").click(function ()
{       
var a = $(this).attr("value");

$("#user").html(a);//here the clicked value is showing in the div name user
console.log(a);//here the clicked value is showing in the console
});

CSS:-

ul{
display: flex;
list-style-type:none;
padding: 20px;
}

li{
padding: 20px;
}

Change :hover CSS properties with JavaScript

This is not actually adding the CSS to the cell, but gives the same effect. While providing the same result as others above, this version is a little more intuitive to me, but I'm a novice, so take it for what it's worth:

$(".hoverCell").bind('mouseover', function() {
    var old_color = $(this).css("background-color");
    $(this)[0].style.backgroundColor = '#ffff00';

    $(".hoverCell").bind('mouseout', function () {
        $(this)[0].style.backgroundColor = old_color;
    });
});

This requires setting the Class for each of the cells you want to highlight to "hoverCell".

Adding and removing style attribute from div with jquery

Remove style attribute from div using J query:

$("#TableDiv").removeAttr("style");

Add style to div using J query:

$("#TableDiv").attr("style", "display: none;");

Add style using html:

<div class="row" id="TableDiv" style="display: none;">
</div>

Hope it will helpful :)

Capture iframe load complete event

Neither of the above answers worked for me, however this did

UPDATE:

As @doppleganger pointed out below, load is gone as of jQuery 3.0, so here's an updated version that uses on. Please note this will actually work on jQuery 1.7+, so you can implement it this way even if you're not on jQuery 3.0 yet.

$('iframe').on('load', function() {
    // do stuff 
});

How to get the week day name from a date?

SQL> SELECT TO_CHAR(date '1982-03-09', 'DAY') day FROM dual;

DAY
---------
TUESDAY

SQL> SELECT TO_CHAR(date '1982-03-09', 'DY') day FROM dual;

DAY
---
TUE

SQL> SELECT TO_CHAR(date '1982-03-09', 'Dy') day FROM dual;

DAY
---
Tue

(Note that the queries use ANSI date literals, which follow the ISO-8601 date standard and avoid date format ambiguity.)

How do you disable browser Autocomplete on web form field / input tag?

Try this :

<input type='text' autocomplete='off' />

Inputting a default image in case the src attribute of an html <img> is not valid?

A modulable version with JQuery, add this at the end of your file:

<script>
    $(function() {
        $('img[data-src-error]').error(function() {
            var o = $(this);
            var errorSrc = o.attr('data-src-error');

            if (o.attr('src') != errorSrc) {
                o.attr('src', errorSrc);
            }
        });
    });
</script>

and on your img tag:

<img src="..." data-src-error="..." />

Cron and virtualenv

If you're on python and using a Conda Virtual Environment where your python script contains the shebang #!/usr/bin/env python the following works:

* * * * * cd /home/user/project && /home/user/anaconda3/envs/envname/bin/python script.py 2>&1

Additionally, if you want to capture any outputs in your script (e.g. print, errors, etc) you can use the following:

* * * * * cd /home/user/project && /home/user/anaconda3/envs/envname/bin/python script.py >> /home/user/folder/script_name.log 2>&1

Stop handler.postDelayed()

this may be old, but for those looking for answer you can use this...

public void stopHandler() {
   handler.removeMessages(0);
}

cheers

Installing mcrypt extension for PHP on OSX Mountain Lion

mycrypt.o and mcrypt_filter.o are in the ext/.libs of your php downloaded directory. Just copy the files to ext/mcrypt, then run make && make install again.

Vertical Alignment of text in a table cell

If you are using Bootstrap, please add the following customised style setting for your table:

.table>tbody>tr>td, 
.table>tbody>tr>th, 
.table>tfoot>tr>td, 
.table>tfoot>tr>th, 
.table>thead>tr>td, 
.table>thead>tr>th {
      vertical-align: middle;
 }

What's better at freeing memory with PHP: unset() or $var = null

<?php
$start = microtime(true);
for ($i = 0; $i < 10000000; $i++) {
    $a = 'a';
    $a = NULL;
}
$elapsed = microtime(true) - $start;

echo "took $elapsed seconds\r\n";



$start = microtime(true);
for ($i = 0; $i < 10000000; $i++) {
    $a = 'a';
    unset($a);
}
$elapsed = microtime(true) - $start;

echo "took $elapsed seconds\r\n";
?>

Per that it seems like "= null" is faster.

PHP 5.4 results:

  • took 0.88389301300049 seconds
  • took 2.1757180690765 seconds

PHP 5.3 results:

  • took 1.7235369682312 seconds
  • took 2.9490959644318 seconds

PHP 5.2 results:

  • took 3.0069220066071 seconds
  • took 4.7002630233765 seconds

PHP 5.1 results:

  • took 2.6272349357605 seconds
  • took 5.0403649806976 seconds

Things start to look different with PHP 5.0 and 4.4.

5.0:

  • took 10.038941144943 seconds
  • took 7.0874409675598 seconds

4.4:

  • took 7.5352551937103 seconds
  • took 6.6245851516724 seconds

Keep in mind microtime(true) doesn't work in PHP 4.4 so I had to use the microtime_float example given in php.net/microtime / Example #1.

How do you do the "therefore" (?) symbol on a Mac or in Textmate?

From System Preferences, turn on the "Show Keyboard & Character Viewer in menu bar" setting.

Then, the "Character Viewer" menu will pop up a tool that will let you search for any unicode character (by name) and insert it ? you're all set.

Can dplyr package be used for conditional mutating?

The derivedFactor function from mosaic package seems to be designed to handle this. Using this example, it would look like:

library(dplyr)
library(mosaic)
df <- mutate(df, g = derivedFactor(
     "2" = (a == 2 | a == 5 | a == 7 | (a == 1 & b == 4)),
     "3" = (a == 0 | a == 1 | a == 4 | a == 3 |  c == 4),
     .method = "first",
     .default = NA
     ))

(If you want the result to be numeric instead of a factor, you can wrap derivedFactor in an as.numeric call.)

derivedFactor can be used for an arbitrary number of conditionals, too.

Count number of times value appears in particular column in MySQL

Take a look at the Group by function.

What the group by function does is pretuty much grouping the similar value for a given field. You can then show the number of number of time that this value was groupped using the COUNT function.

MySQL Documentation

You can also use the group by function with a good number of other function define by MySQL (see the above link).

mysql> SELECT student_name, AVG(test_score)
    ->        FROM student
    ->        GROUP BY student_name;

No input file specified

disabling PHP-FPM fixed my issue.

How to convert time milliseconds to hours, min, sec format in JavaScript?

Human-readable code for human-readable output and you can extend this to light years or nanoseconds or what have you very intuitively. Obviously you'd want to convert this to a function and re-use some of those intermediate modulo calls.

second = 1000 
minute = second * 60
hour = minute * 60 
day = hour * 24

test = 3 * day + 2 * hour + 11 * minute + 58 * second

console.log(Math.floor(test / day))
console.log(Math.floor(test % day / hour))
console.log(Math.floor(test % day % hour / minute))
console.log(Math.floor(test % day % hour % minute / second))

Android checkbox style

Note: Using Android Support Library v22.1.0 and targeting API level 11 and up? Scroll down to the last update.


My application style is set to Theme.Holo which is dark and I would like the check boxes on my list view to be of style Theme.Holo.Light. I am not trying to create a custom style. The code below doesn't seem to work, nothing happens at all.

At first it may not be apparent why the system exhibits this behaviour, but when you actually look into the mechanics you can easily deduce it. Let me take you through it step by step.

First, let's take a look what the Widget.Holo.Light.CompoundButton.CheckBox style defines. To make things more clear, I've also added the 'regular' (non-light) style definition.

<style name="Widget.Holo.Light.CompoundButton.CheckBox" parent="Widget.CompoundButton.CheckBox" />

<style name="Widget.Holo.CompoundButton.CheckBox" parent="Widget.CompoundButton.CheckBox" />

As you can see, both are empty declarations that simply wrap Widget.CompoundButton.CheckBox in a different name. So let's look at that parent style.

<style name="Widget.CompoundButton.CheckBox">
    <item name="android:background">@android:drawable/btn_check_label_background</item>
    <item name="android:button">?android:attr/listChoiceIndicatorMultiple</item>
</style>

This style references both a background and button drawable. btn_check_label_background is simply a 9-patch and hence not very interesting with respect to this matter. However, ?android:attr/listChoiceIndicatorMultiple indicates that some attribute based on the current theme (this is important to realise) will determine the actual look of the CheckBox.

As listChoiceIndicatorMultiple is a theme attribute, you will find multiple declarations for it - one for each theme (or none if it gets inherited from a parent theme). This will look as follows (with other attributes omitted for clarity):

<style name="Theme">
    <item name="listChoiceIndicatorMultiple">@android:drawable/btn_check</item>
    ...
</style>

<style name="Theme.Holo">
    <item name="listChoiceIndicatorMultiple">@android:drawable/btn_check_holo_dark</item>
    ...
</style>

<style name="Theme.Holo.Light" parent="Theme.Light">
    <item name="listChoiceIndicatorMultiple">@android:drawable/btn_check_holo_light</item>
    ...
</style>

So this where the real magic happens: based on the theme's listChoiceIndicatorMultiple attribute, the actual appearance of the CheckBox is determined. The phenomenon you're seeing is now easily explained: since the appearance is theme-based (and not style-based, because that is merely an empty definition) and you're inheriting from Theme.Holo, you will always get the CheckBox appearance matching the theme.

Now, if you want to change your CheckBox's appearance to the Holo.Light version, you will need to take a copy of those resources, add them to your local assets and use a custom style to apply them.

As for your second question:

Also can you set styles to individual widgets if you set a style to the application?

Absolutely, and they will override any activity- or application-set styles.

Is there any way to set a theme(style with images) to the checkbox widget. (...) Is there anyway to use this selector: link?


Update:

Let me start with saying again that you're not supposed to rely on Android's internal resources. There's a reason you can't just access the internal namespace as you please.

However, a way to access system resources after all is by doing an id lookup by name. Consider the following code snippet:

int id = Resources.getSystem().getIdentifier("btn_check_holo_light", "drawable", "android");
((CheckBox) findViewById(R.id.checkbox)).setButtonDrawable(id);

The first line will actually return the resource id of the btn_check_holo_light drawable resource. Since we established earlier that this is the button selector that determines the look of the CheckBox, we can set it as 'button drawable' on the widget. The result is a CheckBox with the appearance of the Holo.Light version, no matter what theme/style you set on the application, activity or widget in xml. Since this sets only the button drawable, you will need to manually change other styling; e.g. with respect to the text appearance.

Below a screenshot showing the result. The top checkbox uses the method described above (I manually set the text colour to black in xml), while the second uses the default theme-based Holo styling (non-light, that is).

Screenshot showing the result


Update2:

With the introduction of Support Library v22.1.0, things have just gotten a lot easier! A quote from the release notes (my emphasis):

Lollipop added the ability to overwrite the theme at a view by view level by using the android:theme XML attribute - incredibly useful for things such as dark action bars on light activities. Now, AppCompat allows you to use android:theme for Toolbars (deprecating the app:theme used previously) and, even better, brings android:theme support to all views on API 11+ devices.

In other words: you can now apply a theme on a per-view basis, which makes solving the original problem a lot easier: just specify the theme you'd like to apply for the relevant view. I.e. in the context of the original question, compare the results of below:

<CheckBox
    ...
    android:theme="@android:style/Theme.Holo" />

<CheckBox
    ...
    android:theme="@android:style/Theme.Holo.Light" />

The first CheckBox is styled as if used in a dark theme, the second as if in a light theme, regardless of the actual theme set to your activity or application.

Of course you should no longer be using the Holo theme, but instead use Material.

'readline/readline.h' file not found

This command helped me on linux mint when i had exact same problem

gcc filename.c -L/usr/include -lreadline -o filename

You could use alias if you compile it many times Forexample:

alias compilefilename='gcc filename.c -L/usr/include -lreadline -o filename'

Update .NET web service to use TLS 1.2

We actually just upgraded a .NET web service to 4.6 to allow TLS 1.2.

What Artem is saying were the first steps we've done. We recompiled the framework of the web service to 4.6 and we tried change the registry key to enable TLS 1.2, although this didn't work: the connection was still in TLS 1.0. Also, we didn't want to disallow SLL 3.0, TLS 1.0 or TLS 1.1 on the machine: other web services could be using this; we rolled-back our changes on the registry.

We actually changed the Web.Config files to tell IIS: "hey, run me in 4.6 please".

Here's the changes we added in the web.config + recompilation in .NET 4.6:

<system.web>
    <compilation targetFramework="4.6"/> <!-- Changed framework 4.0 to 4.6 -->

    <!--Added this httpRuntime -->
    <httpRuntime targetFramework="4.6" />

    <authentication mode="Windows"/>
    <pages controlRenderingCompatibilityVersion="4.0"/>
</system.web>

And the connection changed to TLS 1.2, because IIS is now running the web service in 4.6 (told explicitly) and 4.6 is using TLS 1.2 by default.

Finding last index of a string in Oracle

Use -1 as the start position:

INSTR('JD-EQ-0001', '-', -1)

Proper way to use **kwargs in Python

Here's another approach:

def my_func(arg1, arg2, arg3):
    ... so something ...

kwargs = {'arg1': 'Value One', 'arg2': 'Value Two', 'arg3': 'Value Three'}
# Now you can call the function with kwargs like this:

my_func(**kwargs)

What is the difference between a token and a lexeme?

Lexeme - A lexeme is a sequence of characters in the source program that matches the pattern for a token and is identified by the lexical analyzer as an instance of that token.

Token - Token is a pair consisting of a token name and an optional token value. The token name is a category of a lexical unit.Common token names are

  • identifiers: names the programmer chooses
  • keywords: names already in the programming language
  • separators (also known as punctuators): punctuation characters and paired-delimiters
  • operators: symbols that operate on arguments and produce results
  • literals: numeric, logical, textual, reference literals

Consider this expression in the programming language C:

sum = 3 + 2;

Tokenized and represented by the following table:

 Lexeme        Token category
------------------------------
sum      |    Identifier
 =       |    Assignment operator
 3       |    Integer literal
 +       |    Addition operator
 2       |    Integer literal
 ;       |    End of statement

Resolve Git merge conflicts in favor of their changes during a pull

If you're already in conflicted state, and you want to just accept all of theirs:

git checkout --theirs .
git add .

If you want to do the opposite:

git checkout --ours .
git add .

This is pretty drastic, so make sure you really want to wipe everything out like this before doing it.

How to add Active Directory user group as login in SQL Server

Here is my observation. I created a login (readonly) for a group windows(AD) user account but, its acting defiantly in different SQL servers. In the SQl servers that users can not see the databases I added view definition checked and also gave database execute permeation to the master database for avoiding error 229. I do not have this issue if I create a login for a user.

PHP exec() vs system() vs passthru()

As drawn from http://php.net/ && Chipmunkninja:

The system() Function

The system function in PHP takes a string argument with the command to execute as well as any arguments you wish passed to that command. This function executes the specified command, and dumps any resulting text to the output stream (either the HTTP output in a web server situation, or the console if you are running PHP as a command line tool). The return of this function is the last line of output from the program, if it emits text output.

The exec() Function

The system function is quite useful and powerful, but one of the biggest problems with it is that all resulting text from the program goes directly to the output stream. There will be situations where you might like to format the resulting text and display it in some different way, or not display it at all.

For this, the exec function in PHP is perfectly adapted. Instead of automatically dumping all text generated by the program being executed to the output stream, it gives you the opportunity to put this text in an array returned in the second parameter to the function:

The shell_exec() Function

Most of the programs we have been executing thus far have been, more or less, real programs1. However, the environment in which Windows and Unix users operate is actually much richer than this. Windows users have the option of using the Windows Command Prompt program, cmd.exe This program is known as a command shell.

The passthru() Function

One fascinating function that PHP provides similar to those we have seen so far is the passthru function. This function, like the others, executes the program you tell it to. However, it then proceeds to immediately send the raw output from this program to the output stream with which PHP is currently working (i.e. either HTTP in a web server scenario, or the shell in a command line version of PHP).

The proc_open() Function and popen() function

proc_open() is similar to popen() but provides a much greater degree of control over the program execution. cmd is the command to be executed by the shell. descriptorspec is an indexed array where the key represents the descriptor number and the value represents how PHP will pass that descriptor to the child process. pipes will be set to an indexed array of file pointers that correspond to PHP's end of any pipes that are created. The return value is a resource representing the process; you should free it using proc_close() when you are finished with it.

Where to place JavaScript in an HTML file?

I would say that it depends of fact what do you planed to achieve with Javascript code:

  • if you planned to insert external your JS script(s), then the best place is in head of the page
  • if you planed to use pages on smartphones, then bottom of page, just before tag.
  • but, if you planned to make combination HTML and JS (dynamically created and populated HTML table, for example) then you must put it where you need it there.

Django - what is the difference between render(), render_to_response() and direct_to_template()?

Render is

def render(request, *args, **kwargs):
    """ Simple wrapper for render_to_response. """
    kwargs['context_instance'] = RequestContext(request)
    return render_to_response(*args, **kwargs)

So there is really no difference between render_to_response except it wraps your context making the template pre-processors work.

Direct to template is a generic view.

There is really no sense in using it here because there is overhead over render_to_response in the form of view function.

Close a div by clicking outside

I'd suggest using the stopPropagation() method as shown in the modified fiddle:

Fiddle

$('body').click(function() {
    $(".popup").hide();
});

$('.popup').click(function(e) {
    e.stopPropagation();
});

That way you can hide the popup when you click on the body, without having to add an extra if, and when you click on the popup, the event doesn't bubble up to the body by going through the popup.

Change the spacing of tick marks on the axis of a plot?

And if you don't want R to add decimals or zeros, you can stop it from drawing the x axis or the y axis or both using ...axt. Then, you can add your own ticks and labels:

plot(x, y, xaxt="n")
plot(x, y, yaxt="n")
axis(1 or 2, at=c(1, 5, 10), labels=c("First", "Second", "Third"))

Sending emails through SMTP with PHPMailer

I had very similar problem for something like an hour, until I figured out what went wrong. My problem was, that I used SSL, instead of ssl. Check is case sensitive in the code. AlexV guided me to the source of the problem. That helo/ehlo -stuff seems irrelevant.

How to toggle boolean state of react component?

Since nobody posted this, I am posting the correct answer. If your new state update depends on the previous state, always use the functional form of setState which accepts as argument a function that returns a new state.

In your case:

this.setState(prevState => ({
  check: !prevState.check
}));

See docs


Since this answer is becoming popular, adding the approach that should be used for React Hooks (v16.8+):

If you are using the useState hook, then use the following code (in case your new state depends on the previous state):

const [check, setCheck] = useState(false);
// ...
setCheck(prevCheck => !prevCheck);

JQuery datepicker language

You need the following line:

<script src="../jquery/development-bundle/ui/i18n/jquery.ui.datepicker-sv.js"></script>

Adjust the path depending on where you put the jquery-files.

Difference between two lists

        List<int> list1 = new List<int>();
        List<int> list2 = new List<int>();
        List<int> listDifference = new List<int>();

        foreach (var item1 in list1)
        {
            foreach (var item2 in list2)
            {
                if (item1 != item2)
                    listDifference.Add(item1);
            }
        }

Equivalent of SQL ISNULL in LINQ?

Looks like the type is boolean and therefore can never be null and should be false by default.

How to get file name when user select a file via <input type="file" />?

I'll answer this question via Simple Javascript that is supported in all browsers that I have tested so far (IE8 to IE11, Chrome, FF etc).

Here is the code.

_x000D_
_x000D_
function GetFileSizeNameAndType()_x000D_
        {_x000D_
        var fi = document.getElementById('file'); // GET THE FILE INPUT AS VARIABLE._x000D_
_x000D_
        var totalFileSize = 0;_x000D_
_x000D_
        // VALIDATE OR CHECK IF ANY FILE IS SELECTED._x000D_
        if (fi.files.length > 0)_x000D_
        {_x000D_
            // RUN A LOOP TO CHECK EACH SELECTED FILE._x000D_
            for (var i = 0; i <= fi.files.length - 1; i++)_x000D_
            {_x000D_
                //ACCESS THE SIZE PROPERTY OF THE ITEM OBJECT IN FILES COLLECTION. IN THIS WAY ALSO GET OTHER PROPERTIES LIKE FILENAME AND FILETYPE_x000D_
                var fsize = fi.files.item(i).size;_x000D_
                totalFileSize = totalFileSize + fsize;_x000D_
                document.getElementById('fp').innerHTML =_x000D_
                document.getElementById('fp').innerHTML_x000D_
                +_x000D_
                '<br /> ' + 'File Name is <b>' + fi.files.item(i).name_x000D_
                +_x000D_
                '</b> and Size is <b>' + Math.round((fsize / 1024)) //DEFAULT SIZE IS IN BYTES SO WE DIVIDING BY 1024 TO CONVERT IT IN KB_x000D_
                +_x000D_
                '</b> KB and File Type is <b>' + fi.files.item(i).type + "</b>.";_x000D_
            }_x000D_
        }_x000D_
        document.getElementById('divTotalSize').innerHTML = "Total File(s) Size is <b>" + Math.round(totalFileSize / 1024) + "</b> KB";_x000D_
    }
_x000D_
    <p>_x000D_
        <input type="file" id="file" multiple onchange="GetFileSizeNameAndType()" />_x000D_
    </p>_x000D_
_x000D_
    <div id="fp"></div>_x000D_
    <p>_x000D_
        <div id="divTotalSize"></div>_x000D_
    </p>
_x000D_
_x000D_
_x000D_

*Please note that we are displaying filesize in KB (Kilobytes). To get in MB divide it by 1024 * 1024 and so on*.

It'll perform file outputs like these on selecting Snapshot of a sample output of this code

How to style a clicked button in CSS

There are three states of button

  • Normal : You can select like this button
  • Hover : You can select like this button:hover
  • Pressed/Clicked : You can select like this button:active

Normal:

.button
 {
     //your css
 }

Active

 .button:active
{
        //your css
}

Hover

 .button:hover
{
        //your css
}

SNIPPET:

Use :active to style the active state of button.

_x000D_
_x000D_
button:active{_x000D_
   background-color:red;_x000D_
}
_x000D_
<button>Click Me</button>
_x000D_
_x000D_
_x000D_

Java generics - ArrayList initialization

A lot of this has to do with polymorphism. When you assign

X = new Y();

X can be much less 'specific' than Y, but not the other way around. X is just the handle you are accessing Y with, Y is the real instantiated thing,

You get an error here because Integer is a Number, but Number is not an Integer.

ArrayList<Integer> a = new ArrayList<Number>(); // compile-time error

As such, any method of X that you call must be valid for Y. Since X is more generally it probably shares some, but not all of Y's methods. Still, any arguments given must be valid for Y.

In your examples with add, an int (small i) is not a valid Object or Integer.

ArrayList<?> a = new ArrayList<?>();

This is no good because you can't actually instantiate an array list containing ?'s. You can declare one as such, and then damn near anything can follow in new ArrayList<Whatever>();

How can you search Google Programmatically Java API

Just an alternative. Searching google and parsing the results can also be done in a generic way using any HTML Parser such as Jsoup in Java. Following is the link to the mentioned example.

Update: Link no longer works. Please look for any other example. https://www.codeforeach.com/java/example-how-to-search-google-using-java

How to play .mp4 video in videoview in android?

Check the format of the video you are rendering. Rendering of mp4 format started from API level 11 and the format must be mp4(H.264)

I encountered the same problem, I had to convert my video to many formats before I hit the format: Use total video converter to convert the video to mp4. It works like a charm.

Bash tool to get nth line from a file

head and pipe with tail will be slow for a huge file. I would suggest sed like this:

sed 'NUMq;d' file

Where NUM is the number of the line you want to print; so, for example, sed '10q;d' file to print the 10th line of file.

Explanation:

NUMq will quit immediately when the line number is NUM.

d will delete the line instead of printing it; this is inhibited on the last line because the q causes the rest of the script to be skipped when quitting.

If you have NUM in a variable, you will want to use double quotes instead of single:

sed "${NUM}q;d" file

C++ Boost: undefined reference to boost::system::generic_category()

Depending on the boost version libboost-system comes with the -mt suffix which should indicate the libraries multithreading capability.

So if -lboost_system cannot be found by the linker try -lboost_system-mt.

FlutterError: Unable to load asset

I put my images in a subdirectory of the assets folder. Whenever I add new images, I restart the application and it works fine.

 assets:
    - assets/sub_folder/

I do this so that I don't have to list each asset name.

How to change the color of an image on hover

An alternative solution would be to use the new CSS mask image functionality which works in everything apart from IE (still not supported in IE11). This would be more versatile and maintainable than some of the other solutions suggested here. You could also more generally use SVG. e.g.

item { mask: url('/mask-image.png'); }

There is an example of using a mask image here:

http://codepen.io/zerostyle/pen/tHimv

and lots of examples here:

http://codepen.io/yoksel/full/fsdbu/

Excel how to find values in 1 column exist in the range of values in another

This is what you need:

 =NOT(ISERROR(MATCH(<cell in col A>,<column B>, 0)))  ## pseudo code

For the first cell of A, this would be:

 =NOT(ISERROR(MATCH(A2,$B$2:$B$5, 0)))

Enter formula (and drag down) as follows:

enter image description here

You will get:

enter image description here

How to find difference between two Joda-Time DateTimes in minutes

Something like...

DateTime today = new DateTime();
DateTime yesterday = today.minusDays(1);

Duration duration = new Duration(yesterday, today);
System.out.println(duration.getStandardDays());
System.out.println(duration.getStandardHours());
System.out.println(duration.getStandardMinutes());

Which outputs

1
24
1440

or

System.out.println(Minutes.minutesBetween(yesterday, today).getMinutes());

Which is probably more what you're after

How to decode Unicode escape sequences like "\u00ed" to proper UTF-8 encoded characters?

Try this:

$str = preg_replace_callback('/\\\\u([0-9a-fA-F]{4})/', function ($match) {
    return mb_convert_encoding(pack('H*', $match[1]), 'UTF-8', 'UCS-2BE');
}, $str);

In case it's UTF-16 based C/C++/Java/Json-style:

$str = preg_replace_callback('/\\\\u([0-9a-fA-F]{4})/', function ($match) {
    return mb_convert_encoding(pack('H*', $match[1]), 'UTF-8', 'UTF-16BE');
}, $str);

What is the .idea folder?

As of year 2020, JetBrains suggests to commit the .idea folder.
The JetBrains IDEs (webstorm, intellij, android studio, pycharm, clion, etc.) automatically add that folder to your git repository (if there's one).
Inside the folder .idea, has been already created a .gitignore, updated by the IDE itself to avoid to commit user related settings that may contains privacy/password data.

It is safe (and usually useful) to commit the .idea folder.

How can I present a file for download from an MVC controller?

Although standard action results FileContentResult or FileStreamResult may be used for downloading files, for reusability, creating a custom action result might be the best solution.

As an example let's create a custom action result for exporting data to Excel files on the fly for download.

ExcelResult class inherits abstract ActionResult class and overrides the ExecuteResult method.

We are using FastMember package for creating DataTable from IEnumerable object and ClosedXML package for creating Excel file from the DataTable.

public class ExcelResult<T> : ActionResult
{
    private DataTable dataTable;
    private string fileName;

    public ExcelResult(IEnumerable<T> data, string filename, string[] columns)
    {
        this.dataTable = new DataTable();
        using (var reader = ObjectReader.Create(data, columns))
        {
            dataTable.Load(reader);
        }
        this.fileName = filename;
    }

    public override void ExecuteResult(ControllerContext context)
    {
        if (context != null)
        {
            var response = context.HttpContext.Response;
            response.Clear();
            response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
            response.AddHeader("content-disposition", string.Format(@"attachment;filename=""{0}""", fileName));
            using (XLWorkbook wb = new XLWorkbook())
            {
                wb.Worksheets.Add(dataTable, "Sheet1");
                using (MemoryStream stream = new MemoryStream())
                {
                    wb.SaveAs(stream);
                    response.BinaryWrite(stream.ToArray());
                }
            }
        }
    }
}

In the Controller use the custom ExcelResult action result as follows

[HttpGet]
public async Task<ExcelResult<MyViewModel>> ExportToExcel()
{
    var model = new Models.MyDataModel();
    var items = await model.GetItems();
    string[] columns = new string[] { "Column1", "Column2", "Column3" };
    string filename = "mydata.xlsx";
    return new ExcelResult<MyViewModel>(items, filename, columns);
}

Since we are downloading the file using HttpGet, create an empty View without model and empty layout.

Blog post about custom action result for downloading files that are created on the fly:

https://acanozturk.blogspot.com/2019/03/custom-actionresult-for-files-in-aspnet.html

Save bitmap to file function

implementation save bitmap and load bitmap directly. fast and ease on mfc class

void CMRSMATH1Dlg::Loadit(TCHAR *destination, CDC &memdc)
{
CImage img;
PBITMAPINFO bmi;
BITMAPINFOHEADER Info;
BITMAPFILEHEADER bFileHeader;
CBitmap bm;     
CFile file2;
file2.Open(destination, CFile::modeRead | CFile::typeBinary);
file2.Read(&bFileHeader, sizeof(BITMAPFILEHEADER));
file2.Read(&Info, sizeof(BITMAPINFOHEADER));    
BYTE ch;
int width = Info.biWidth;
int height = Info.biHeight;
if (height < 0)height = -height;
int size1 = width*height * 3;
int size2 = ((width * 24 + 31) / 32) * 4 * height;
int widthnew = (size2 - size1) / height;
BYTE * buffer = (BYTE *)GlobalAlloc(GPTR, size2);
//////////////////////////
HGDIOBJ old;
unsigned char alpha = 0;    
int z = 0;  
z = 0;
int gap = (size2 - size1) / height;
for (int y = 0;y < height;y++)
{
    for (int x = 0;x < width*3;x++)
    {
        file2.Read(&ch, 1);
        buffer[z] = ch;
        z++;
    }
    for (int z1 = 0;z1 <gap;z1++)
    {
        file2.Read(&ch,1);
    }
}
bm.CreateCompatibleBitmap(&memdc, width, height);
bm.SetBitmapBits(size1,buffer);
old = memdc.SelectObject(&bm);   
///////////////////////////  
 //bm.SetBitmapBits(size1, buffer);     
 GetDC()->BitBlt(1, 95, width, height, &memdc, 0, 0, SRCCOPY);
 memdc.SelectObject(&old);
 bm.DeleteObject();
 GlobalFree(buffer);     
 file2.Close();
 }
 void CMRSMATH1Dlg::saveit(CBitmap &bit1, CDC &memdc, TCHAR *destination)
  {     
BITMAP bm;
PBITMAPINFO bmi;
BITMAPINFOHEADER Info;
BITMAPFILEHEADER bFileHeader;
CFile file1;
            CSize size = bit1.GetBitmap(&bm);
 int z = 0;  
 BYTE ch = 0;
 size.cx = bm.bmWidth;
 size.cy = bm.bmHeight;
 int width = size.cx;    
 int size1 = (size.cx)*(size.cy);
 int size2 = size1 * 3;  
 size1 = ((size.cx * 24 + 31) / 32) *4* size.cy;     
 BYTE * buffer = (BYTE *)GlobalAlloc(GPTR, size2);               
 bFileHeader.bfType = 'B' + ('M' << 8); 
 bFileHeader.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);
 bFileHeader.bfSize = bFileHeader.bfOffBits + size1;
 bFileHeader.bfReserved1 = 0;
 bFileHeader.bfReserved2 = 0;   
 Info.biSize = sizeof(BITMAPINFOHEADER);
 Info.biPlanes = 1;
 Info.biBitCount = 24;//bm.bmBitsPixel;//bitsperpixel///////////////////32
 Info.biCompression = BI_RGB;
 Info.biWidth =bm.bmWidth;
 Info.biHeight =-bm.bmHeight;///reverse pic if negative height
 Info.biSizeImage =size1;
 Info.biClrImportant = 0;
 if (bm.bmBitsPixel <= 8)
 {
     Info.biClrUsed = 1 << bm.bmBitsPixel;
 }else
 Info.biClrUsed = 0;
 Info.biXPelsPerMeter = 0;
 Info.biYPelsPerMeter = 0;
 bit1.GetBitmapBits(size2, buffer);      
 file1.Open(destination, CFile::modeCreate | CFile::modeWrite |CFile::typeBinary,0);
 file1.Write(&bFileHeader, sizeof(BITMAPFILEHEADER));
 file1.Write(&Info, sizeof(BITMAPINFOHEADER));
 unsigned char alpha = 0;    
 for (int y = 0;y<size.cy;y++)
 {
     for (int x = 0;x<size.cx;x++)
     {
         //for reverse picture below
         //z = (((size.cy - 1 - y)*size.cx) + (x)) * 3;          
     z = (((y)*size.cx) + (x)) * 3;
     file1.Write(&buffer[z], 1);
     file1.Write(&buffer[z + 1], 1);
     file1.Write(&buffer[z + 2], 1);
     }               
     for (int z = 0;z < (size1 - size2) / size.cy;z++)
     {
         file1.Write(&alpha, 1);
     }
 }   
 GlobalFree(buffer);     
 file1.Close();  
 file1.m_hFile = NULL;
        }

error NG6002: Appears in the NgModule.imports of AppModule, but could not be resolved to an NgModule class

Fixed it by opting out of Ivy as per documentation.

https://angular.io/guide/ivy

Change tsconfig.app.json to opt out of Ivy.

"enableIvy": false

Multiple separate IF conditions in SQL Server

Maybe this is a bit redundant, but no one appeared to have mentioned this as a solution.

As a beginner in SQL I find that when using a BEGIN and END SSMS usually adds a squiggly line with incorrect syntax near 'END' to END, simply because there's no content in between yet. If you're just setting up BEGIN and END to get started and add the actual query later, then simply add a bogus PRINT statement so SSMS stops bothering you.

For example:

IF (1=1)
BEGIN
  PRINT 'BOGUS'
END

The following will indeed set you on the wrong track, thinking you made a syntax error which in this case just means you still need to add content in between BEGIN and END:

IF (1=1)
BEGIN
END

How do I add python3 kernel to jupyter (IPython)

  1. Got ipython notebook with Python2 (on Windows7)
  2. upgrade to Jupyter with pip install -U jupyter
  3. install Python3
  4. install Jupyter again using pip3 install jupyter
  5. install Python3 kernel using ipython3 kernelspec install-self
  6. I finally got 2 working kernels.

great results

Single line if statement with 2 actions

You can write that in single line, but it's not something that someone would be able to read. Keep it like you already wrote it, it's already beautiful by itself.

If you have too much if/else constructs, you may think about using of different datastructures, like Dictionaries (to look up keys) or Collection (to run conditional LINQ queries on it)

What's the yield keyword in JavaScript?

The MDN documentation is pretty good, IMO.

The function containing the yield keyword is a generator. When you call it, its formal parameters are bound to actual arguments, but its body isn't actually evaluated. Instead, a generator-iterator is returned. Each call to the generator-iterator's next() method performs another pass through the iterative algorithm. Each step's value is the value specified by the yield keyword. Think of yield as the generator-iterator version of return, indicating the boundary between each iteration of the algorithm. Each time you call next(), the generator code resumes from the statement following the yield.

Check if any type of files exist in a directory using BATCH script

For files in a directory, you can use things like:

if exist *.csv echo "csv file found"

or

if not exist *.csv goto nofile

Update MongoDB field using value of another field

Here's what we came up with for copying one field to another for ~150_000 records. It took about 6 minutes, but is still significantly less resource intensive than it would have been to instantiate and iterate over the same number of ruby objects.

js_query = %({
  $or : [
    {
      'settings.mobile_notifications' : { $exists : false },
      'settings.mobile_admin_notifications' : { $exists : false }
    }
  ]
})

js_for_each = %(function(user) {
  if (!user.settings.hasOwnProperty('mobile_notifications')) {
    user.settings.mobile_notifications = user.settings.email_notifications;
  }
  if (!user.settings.hasOwnProperty('mobile_admin_notifications')) {
    user.settings.mobile_admin_notifications = user.settings.email_admin_notifications;
  }
  db.users.save(user);
})

js = "db.users.find(#{js_query}).forEach(#{js_for_each});"
Mongoid::Sessions.default.command('$eval' => js)

Add a reference column migration in Rails 4

if you like another alternate approach with up and down method try this:

  def up
    change_table :uploads do |t|
      t.references :user, index: true
    end
  end

  def down
    change_table :uploads do |t|
      t.remove_references :user, index: true
    end
  end

EL access a map value by Integer key

You can use all functions from Long, if you put the number into "(" ")". That way you can cast the long to an int:

<c:out value="${map[(1).intValue()]}"/>

How to sort dates from Oldest to Newest in Excel?

Here's how to sort unsorted dates:

Drag down the column to select the dates you want to sort.

Click Home tab > arrow under Sort & Filter, and then click Sort Oldest to Newest, or Sort Newest to Oldest.

NOTE: If the results aren't what you expected, the column might have dates that are stored as text instead of dates. Convert dates stored as text to dates.

Shell script variable not empty (-z option)

Of course it does. After replacing the variable, it reads [ !-z ], which is not a valid [ command. Use double quotes, or [[.

if [ ! -z "$errorstatus" ]

if [[ ! -z $errorstatus ]]

Should a 502 HTTP status code be used if a proxy receives no response at all?

Yes. Empty or incomplete headers or response body typically caused by broken connections or server side crash can cause 502 errors if accessed via a gateway or proxy.

For more information about the network errors

https://en.wikipedia.org/wiki/List_of_HTTP_status_codes

Using Tempdata in ASP.NET MVC - Best practice

Please note that MVC 3 onwards the persistence behavior of TempData has changed, now the value in TempData is persisted until it is read, and not just for the next request.

The value of TempData persists until it is read or until the session times out. Persisting TempData in this way enables scenarios such as redirection, because the values in TempData are available beyond a single request. https://msdn.microsoft.com/en-in/library/dd394711%28v=vs.100%29.aspx

How to validate an email address in PHP

Answered this in 'top question' about emails verification https://stackoverflow.com/a/41129750/1848217

For me the right way for checking emails is:

  1. Check that symbol @ exists, and before and after it there are some non-@ symbols: /^[^@]+@[^@]+$/
  2. Try to send an email to this address with some "activation code".
  3. When the user "activated" his email address, we will see that all is right.

Of course, you can show some warning or tooltip in front-end when user typed "strange" email to help him to avoid common mistakes, like no dot in domain part or spaces in name without quoting and so on. But you must accept the address "hello@world" if user really want it.

Also, you must remember that email address standard was and can evolute, so you can't just type some "standard-valid" regexp once and for all times. And you must remember that some concrete internet servers can fail some details of common standard and in fact work with own "modified standard".

So, just check @, hint user on frontend and send verification emails on given address.

Python handling socket.error: [Errno 104] Connection reset by peer

You can try to add some time.sleep calls to your code.

It seems like the server side limits the amount of requests per timeunit (hour, day, second) as a security issue. You need to guess how many (maybe using another script with a counter?) and adjust your script to not surpass this limit.

In order to avoid your code from crashing, try to catch this error with try .. except around the urllib2 calls.

Does Java have an exponential operator?

There is the Math.pow(double a, double b) method. Note that it returns a double, you will have to cast it to an int like (int)Math.pow(double a, double b).

What's the difference between "end" and "exit sub" in VBA?

This is a bit outside the scope of your question, but to avoid any potential confusion for readers who are new to VBA: End and End Sub are not the same. They don't perform the same task.

End puts a stop to ALL code execution and you should almost always use Exit Sub (or Exit Function, respectively).

End halts ALL exectution. While this sounds tempting to do it also clears all global and static variables. (source)

See also the MSDN dox for the End Statement

When executed, the End statement resets allmodule-level variables and all static local variables in allmodules. To preserve the value of these variables, use the Stop statement instead. You can then resume execution while preserving the value of those variables.

Note The End statement stops code execution abruptly, without invoking the Unload, QueryUnload, or Terminate event, or any other Visual Basic code. Code you have placed in the Unload, QueryUnload, and Terminate events offorms andclass modules is not executed. Objects created from class modules are destroyed, files opened using the Open statement are closed, and memory used by your program is freed. Object references held by other programs are invalidated.

Nor is End Sub and Exit Sub the same. End Sub can't be called in the same way Exit Sub can be, because the compiler doesn't allow it.

enter image description here

This again means you have to Exit Sub, which is a perfectly legal operation:

Exit Sub
Immediately exits the Sub procedure in which it appears. Execution continues with the statement following the statement that called the Sub procedure. Exit Sub can be used only inside a Sub procedure.

Additionally, and once you get the feel for how procedures work, obviously, End Sub does not clear any global variables. But it does clear local (Dim'd) variables:

End Sub
Terminates the definition of this procedure.

@RequestParam vs @PathVariable

@RequestParam is use for query parameter(static values) like: http://localhost:8080/calculation/pow?base=2&ext=4

@PathVariable is use for dynamic values like : http://localhost:8080/calculation/sqrt/8

@RequestMapping(value="/pow", method=RequestMethod.GET)
public int pow(@RequestParam(value="base") int base1, @RequestParam(value="ext") int ext1){
    int pow = (int) Math.pow(base1, ext1);
    return pow;
}

@RequestMapping("/sqrt/{num}")
public double sqrt(@PathVariable(value="num") int num1){
    double sqrtnum=Math.sqrt(num1);
    return sqrtnum;
}

What is the difference between public, protected, package-private and private in Java?

Java access modifies which you can use

enter image description here

Access modifier can be applicable for class, field[About], method. Try to access, subclass or override this.

  • Access to field or method is through a class.
  • Inheritance and Open Closed Principle.
    • Successor class(subclass) access modifier can be any.
    • Successor method(override) access modifier should be the same or expand it

Top level class(first level scope) can be public and default. Nested class[About] can have any of them

package is not applying for package hierarchy

[Swift access modifiers]

Inheritance with base class constructor with parameters

I could be wrong, but I believe since you are inheriting from foo, you have to call a base constructor. Since you explicitly defined the foo constructor to require (int, int) now you need to pass that up the chain.

public bar(int a, int b) : base(a, b)
{
     c = a * b;
}

This will initialize foo's variables first and then you can use them in bar. Also, to avoid confusion I would recommend not naming parameters the exact same as the instance variables. Try p_a or something instead, so you won't accidentally be handling the wrong variable.

Git error when trying to push -- pre-receive hook declined

In my case I got this error because a branch with the same name already existed. Deleting this branch off of the git server will fix this.

How does String substring work in Swift

I had the same initial reaction. I too was frustrated at how syntax and objects change so drastically in every major release.

However, I realized from experience how I always eventually suffer the consequences of trying to fight "change" like dealing with multi-byte characters which is inevitable if you're looking at a global audience.

So I decided to recognize and respect the efforts exerted by Apple engineers and do my part by understanding their mindset when they came up with this "horrific" approach.

Instead of creating extensions which is just a workaround to make your life easier (I'm not saying they're wrong or expensive), why not figure out how Strings are now designed to work.

For instance, I had this code which was working on Swift 2.2:

let rString = cString.substringToIndex(2)
let gString = (cString.substringFromIndex(2) as NSString).substringToIndex(2)
let bString = (cString.substringFromIndex(4) as NSString).substringToIndex(2)

and after giving up trying to get the same approach working e.g. using Substrings, I finally understood the concept of treating Strings as a bidirectional collection for which I ended up with this version of the same code:

let rString = String(cString.characters.prefix(2))
cString = String(cString.characters.dropFirst(2))
let gString = String(cString.characters.prefix(2))
cString = String(cString.characters.dropFirst(2))
let bString = String(cString.characters.prefix(2))

I hope this contributes...

How to get everything after a certain character?

$string = "233718_This_is_a_string";
$withCharacter = strstr($string, '_'); // "_This_is_a_string"
echo substr($withCharacter, 1); // "This_is_a_string"

In a single statement it would be.

echo substr(strstr("233718_This_is_a_string", '_'), 1); // "This_is_a_string"

Python Pandas Error tokenizing data

The parser is getting confused by the header of the file. It reads the first row and infers the number of columns from that row. But the first two rows aren't representative of the actual data in the file.

Try it with data = pd.read_csv(path, skiprows=2)

How can you tell if a value is not numeric in Oracle?

REGEXP_LIKE(column, '^[[:digit:]]+$')

returns TRUE if column holds only numeric characters

How to set MouseOver event/trigger for border in XAML?

Yes, this is confusing...

According to this blog post, it looks like this is an omission from WPF.

To make it work you need to use a style:

    <Border Name="ClearButtonBorder" Grid.Column="1" CornerRadius="0,3,3,0">
        <Border.Style>
            <Style>
                <Setter Property="Border.Background" Value="Blue"/>
                <Style.Triggers>
                    <Trigger Property="Border.IsMouseOver" Value="True">
                        <Setter Property="Border.Background" Value="Green" />
                    </Trigger>
                </Style.Triggers>
            </Style>
        </Border.Style>
        <TextBlock HorizontalAlignment="Center" VerticalAlignment="Center" Text="X" />
    </Border>

I guess this problem isn't that common as most people tend to factor out this sort of thing into a style, so it can be used on multiple controls.

How to delete a folder with files using Java

As mentioned, Java isn't able to delete a folder that contains files, so first delete the files and then the folder.

Here's a simple example to do this:

import org.apache.commons.io.FileUtils;



// First, remove files from into the folder 
FileUtils.cleanDirectory(folder/path);

// Then, remove the folder
FileUtils.deleteDirectory(folder/path);

Or:

FileUtils.forceDelete(new File(destination));

Using Django time/date widgets in custom form

Updated solution and workaround for SplitDateTime with required=False:

forms.py

from django import forms

class SplitDateTimeJSField(forms.SplitDateTimeField):
    def __init__(self, *args, **kwargs):
        super(SplitDateTimeJSField, self).__init__(*args, **kwargs)
        self.widget.widgets[0].attrs = {'class': 'vDateField'}
        self.widget.widgets[1].attrs = {'class': 'vTimeField'}  


class AnyFormOrModelForm(forms.Form):
    date = forms.DateField(widget=forms.TextInput(attrs={'class':'vDateField'}))
    time = forms.TimeField(widget=forms.TextInput(attrs={'class':'vTimeField'}))
    timestamp = SplitDateTimeJSField(required=False,)

form.html

<script type="text/javascript" src="/admin/jsi18n/"></script>
<script type="text/javascript" src="/admin_media/js/core.js"></script>
<script type="text/javascript" src="/admin_media/js/calendar.js"></script>
<script type="text/javascript" src="/admin_media/js/admin/DateTimeShortcuts.js"></script>

urls.py

(r'^admin/jsi18n/', 'django.views.i18n.javascript_catalog'),

C: scanf to array

The %d conversion specifier will only convert one decimal integer. It doesn't know that you're passing an array, it can't modify its behavior based on that. The conversion specifier specifies the conversion.

There is no specifier for arrays, you have to do it explicitly. Here's an example with four conversions:

if(scanf("%d %d %d %d", &array[0], &array[1], &array[2], &array[3]) == 4)
  printf("got four numbers\n");

Note that this requires whitespace between the input numbers.

If the id is a single 11-digit number, it's best to treat as a string:

char id[12];

if(scanf("%11s", id) == 1)
{
  /* inspect the *character* in id[0], compare with '1' or '2' for instance. */
}

How to create custom exceptions in Java?

For a checked exception:

public class MyCustomException extends Exception { }

Technically, anything that extends Throwable can be an thrown, but exceptions are generally extensions of the Exception class so that they're checked exceptions (except RuntimeException or classes based on it, which are not checked), as opposed to the other common type of throwable, Errors which usually are not something designed to be gracefully handled beyond the JVM internals.

You can also make exceptions non-public, but then you can only use them in the package that defines them, as opposed to across packages.

As far as throwing/catching custom exceptions, it works just like the built-in ones - throw via

throw new MyCustomException()

and catch via

catch (MyCustomException e) { }

Changing the interval of SetInterval while it's running

You can use a variable and change the variable instead.

````setInterval([the function], [the variable])```

Python: Is there an equivalent of mid, right, and left from BASIC?

There are built-in functions in Python for "right" and "left", if you are looking for a boolean result.

str = "this_is_a_test"
left = str.startswith("this")
print(left)
> True

right = str.endswith("test")
print(right)
> True

Can I limit the length of an array in JavaScript?

You're not using splice correctly:

arr.splice(4, 1)

this will remove 1 item at index 4. see here

I think you want to use slice:

arr.slice(0,5)

this will return elements in position 0 through 4.

This assumes all the rest of your code (cookies etc) works correctly

Where can I read the Console output in Visual Studio 2015

You should use Console.ReadLine() if you want to read some input from the console.

To see your code running in Console:

In Solution Explorer (View - Solution Explorer from the menu), right click on your project, select Open Folder in File Explorer, to find where your project path is.

Supposedly the path is C:\code\myProj .

Open the Command Prompt app in Windows.

Change to your folder path. cd C:\code\myProj

Change to the debug folder, where you should find your program executable. cd bin\debug

Run your program executable, it should end in .exe extension.

Example:

myproj.exe

You should see what you output in Console.Out.WriteLine() .

Get all files that have been modified in git branch

git diff --name-only master...branch-name

to which we want to compare.

How to drop all tables from a database with one SQL query?

If you want to use only one SQL query to delete all tables you can use this:

EXEC sp_MSforeachtable @command1 = "DROP TABLE ?"

This is a hidden Stored Procedure in sql server, and will be executed for each table in the database you're connected.

Note: You may need to execute the query a few times to delete all tables due to dependencies.

Note2: To avoid the first note, before running the query, first check if there foreign keys relations to any table. If there are then just disable foreign key constraint by running the query bellow:

EXEC sp_msforeachtable "ALTER TABLE ? NOCHECK CONSTRAINT all"

cor shows only NA or 1 for correlations - Why?

The NA can actually be due to 2 reasons. One is that there is a NA in your data. Another one is due to there being one of the values being constant. This results in standard deviation being equal to zero and hence the cor function returns NA.

Call PHP function from Twig template

There is already a Twig extension that lets you call PHP functions form your Twig templates like:

Hi, I am unique: {{ uniqid() }}.

And {{ floor(7.7) }} is floor of 7.7.

See official extension repository.

Enterprise app deployment doesn't work on iOS 7.1

After reading this post I had still a problem with downloading my app. Problem was because of self signed SSL certificate.

I've found a solution for this problem. You need to upload your certificate file with extension '.crt' on the web and type address of it in your mobile safari. System ask you about adding your certificate to the list of trusted certificates. After this operation you will be able to install your ad-hoc app.

Increment counter with loop

The varStatus references to LoopTagStatus which has a getIndex() method.

So:

<c:forEach var="tableEntity" items='${requestScope.tables}' varStatus="outer">
   <c:forEach var="rowEntity" items='${tableEntity.rows}' varStatus="inner">            
        <c:out value="${(outer.index * fn:length(tableEntity.rows)) + inner.index}" />
    </c:forEach>
</c:forEach>

See also:

data type not understood

Try:

mmatrix = np.zeros((nrows, ncols))

Since the shape parameter has to be an int or sequence of ints

http://docs.scipy.org/doc/numpy/reference/generated/numpy.zeros.html

Otherwise you are passing ncols to np.zeros as the dtype.

Java URL encoding of query string parameters

In my case i just needed to pass the whole url and encode only the value of each parameters. I didn't find a common code to do that so (!!) so i created this small method to do the job :

public static String encodeUrl(String url) throws Exception {
    if (url == null || !url.contains("?")) {
        return url;
    }

    List<String> list = new ArrayList<>();
    String rootUrl = url.split("\\?")[0] + "?";
    String paramsUrl = url.replace(rootUrl, "");
    List<String> paramsUrlList = Arrays.asList(paramsUrl.split("&"));
    for (String param : paramsUrlList) {
        if (param.contains("=")) {
            String key = param.split("=")[0];
            String value = param.replace(key + "=", "");
            list.add(key + "=" +  URLEncoder.encode(value, "UTF-8"));
        }
        else {
            list.add(param);
        }
    }

    return rootUrl + StringUtils.join(list, "&");
}

public static String decodeUrl(String url) throws Exception {
    return URLDecoder.decode(url, "UTF-8");
}

It uses org.apache.commons.lang3.StringUtils

How can I get the Google cache age of any URL or web page?

you can Use CachedPages website

Cached pages are usually saved and stored by large companies with powerful web servers. Since such servers are usually very fast, a cached page can often be accessed faster than the live page itself:

  • Google usually keeps a recent copy of the page (1 to 15 days old).
  • Coral also keeps a recent copy, although it's usually not as recent as Google.
  • Through Archive.org, you can access several copies of a web page saved throughout the years.

In NetBeans how do I change the Default JDK?

If I remember correctly, you'll need to set the netbeans_jdkhome property in your netbeans config file. Should be in your etc/netbeans.conf file.

Check if process returns 0 with batch file

To check whether a process/command returned 0 or not, use the operators && == 0 or not == 0 ||:

Just add operator to your script:

execute_command && (

       echo\Return 0, with no execution error
) || (
        echo\Return non 0, something went wrong
     )

command && echo\Return 0 || echo\Return non 0

Java project in Eclipse: The type java.lang.Object cannot be resolved. It is indirectly referenced from required .class files

Here is how I solved it: In Java-ADT: Windows - Preference - Java - Installed JREs Just add another JRE, pointing to the 'jre' folder under your JDK folder. (jre is included in the jdk). Make sure you chose the new jre.

Disabling radio buttons with jQuery

I just built a sandbox environment with your code and it worked for me. Here is what I used:

<html>
  <head>
    <title>test</title>
    <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"></script>
  </head>
  <body>
    <form id="chatTickets" method="post" action="/admin/index.cfm/">
      <input id="ticketID1" type="radio" checked="checked" value="myvalue1" name="ticketID"/>
      <input id="ticketID2" type="radio" checked="checked" value="myvalue2" name="ticketID"/>
    </form>
    <a href="#" title="Load ActiveChat" id="loadActive">Load Active</a>

    <script>
      jQuery("#loadActive").click(function() {
        //I have other code in here that runs before this function call
        writeData();
      });
      function writeData() {
        jQuery("input[name='ticketID']").each(function(i) {
            jQuery(this).attr('disabled', 'disabled');
        });
      }
    </script>
  </body>
</html>

I tested in FF3.5, moving to IE8 now. And it works fine in IE8 too. What browser are you using?

How to delete a folder and all contents using a bat file in windows?

  1. del /s /q c:\where ever the file is\*
  2. rmdir /s /q c:\where ever the file is\
  3. mkdir c:\where ever the file is\

Case-insensitive search in Rails model

Assuming that you use mysql, you could use fields that are not case sensitive: http://dev.mysql.com/doc/refman/5.0/en/case-sensitivity.html

Python string prints as [u'String']

Use dir or type on the 'string' to find out what it is. I suspect that it's one of BeautifulSoup's tag objects, that prints like a string, but really isn't one. Otherwise, its inside a list and you need to convert each string separately.

In any case, why are you objecting to using Unicode? Any specific reason?

Error - replacement has [x] rows, data has [y]

The answer by @akrun certainly does the trick. For future googlers who want to understand why, here is an explanation...

The new variable needs to be created first.

The variable "valueBin" needs to be already in the df in order for the conditional assignment to work. Essentially, the syntax of the code is correct. Just add one line in front of the code chuck to create this name --

df$newVariableName <- NA

Then you continue with whatever conditional assignment rules you have, like

df$newVariableName[which(df$oldVariableName<=250)] <- "<=250"

I blame whoever wrote that package's error message... The debugging was made especially confusing by that error message. It is irrelevant information that you have two arrays in the df with different lengths. No. Simply create the new column first. For more details, consult this post https://www.r-bloggers.com/translating-weird-r-errors/

String Padding in C

The argument you passed "Hello" is on the constant data area. Unless you've allocated enough memory to char * string, it's overrunning to other variables.

char buffer[1024];
memset(buffer, 0, sizeof(buffer));
strncpy(buffer, "Hello", sizeof(buffer));
StringPadRight(buffer, 10, "0");

Edit: Corrected from stack to constant data area.

Get Time from Getdate()

You might want to check out this old thread.

If you can omit AM/PM portion and using SQL Server 2008, you should go with the approach suggested here

To get the rid from nenoseconds in time(SQL Server 2008), do as below :

SELECT CONVERT(TIME(0),GETDATE()) AS HourMinuteSecond

I hope it helps!!

Store a closure as a variable in Swift

For me following was working:

var completionHandler:((Float)->Void)!

Order a MySQL table by two columns

The following will order your data depending on both column in descending order.

ORDER BY article_rating DESC, article_time DESC

How can I display an RTSP video stream in a web page?

the Microsoft Mediaplayer can do all, you need. I use the MS Mediaservices of 2003 / 2008 Server to deliver Video as Broadcast and Unicast Stream. This Service could GET the Stream from the cam and Broadcast it. Than you have "only" the Problem to "Display" that Picture in ALL Browers at all OS-Systems

My Tip :check first the OS , than load your plugin . on Windows it is easy -take WMP , on other take MS Silverligt ...

Preferred method to store PHP arrays (json_encode vs serialize)

First, I changed the script to do some more benchmarking (and also do 1000 runs instead of just 1):

<?php

ini_set('display_errors', 1);
error_reporting(E_ALL);

// Make a big, honkin test array
// You may need to adjust this depth to avoid memory limit errors
$testArray = fillArray(0, 5);

$totalJsonTime = 0;
$totalSerializeTime = 0;
$totalJsonWins = 0;

for ($i = 0; $i < 1000; $i++) {
    // Time json encoding
    $start = microtime(true);
    $json = json_encode($testArray);
    $jsonTime = microtime(true) - $start;
    $totalJsonTime += $jsonTime;

    // Time serialization
    $start = microtime(true);
    $serial = serialize($testArray);
    $serializeTime = microtime(true) - $start;
    $totalSerializeTime += $serializeTime;

    if ($jsonTime < $serializeTime) {
        $totalJsonWins++;
    }
}

$totalSerializeWins = 1000 - $totalJsonWins;

// Compare them
if ($totalJsonTime < $totalSerializeTime) {
    printf("json_encode() (wins: $totalJsonWins) was roughly %01.2f%% faster than serialize()\n", ($totalSerializeTime / $totalJsonTime - 1) * 100);
} else {
    printf("serialize() (wins: $totalSerializeWins) was roughly %01.2f%% faster than json_encode()\n", ($totalJsonTime / $totalSerializeTime - 1) * 100);
}

$totalJsonTime = 0;
$totalJson2Time = 0;
$totalSerializeTime = 0;
$totalJsonWins = 0;

for ($i = 0; $i < 1000; $i++) {
    // Time json decoding
    $start = microtime(true);
    $orig = json_decode($json, true);
    $jsonTime = microtime(true) - $start;
    $totalJsonTime += $jsonTime;

    $start = microtime(true);
    $origObj = json_decode($json);
    $jsonTime2 = microtime(true) - $start;
    $totalJson2Time += $jsonTime2;

    // Time serialization
    $start = microtime(true);
    $unserial = unserialize($serial);
    $serializeTime = microtime(true) - $start;
    $totalSerializeTime += $serializeTime;

    if ($jsonTime < $serializeTime) {
        $totalJsonWins++;
    }
}

$totalSerializeWins = 1000 - $totalJsonWins;


// Compare them
if ($totalJsonTime < $totalSerializeTime) {
    printf("json_decode() was roughly %01.2f%% faster than unserialize()\n", ($totalSerializeTime / $totalJsonTime - 1) * 100);
} else {
    printf("unserialize() (wins: $totalSerializeWins) was roughly %01.2f%% faster than json_decode()\n", ($totalJsonTime / $totalSerializeTime - 1) * 100);
}

// Compare them
if ($totalJson2Time < $totalSerializeTime) {
    printf("json_decode() was roughly %01.2f%% faster than unserialize()\n", ($totalSerializeTime / $totalJson2Time - 1) * 100);
} else {
    printf("unserialize() (wins: $totalSerializeWins) was roughly %01.2f%% faster than array json_decode()\n", ($totalJson2Time / $totalSerializeTime - 1) * 100);
}

function fillArray( $depth, $max ) {
    static $seed;
    if (is_null($seed)) {
        $seed = array('a', 2, 'c', 4, 'e', 6, 'g', 8, 'i', 10);
    }
    if ($depth < $max) {
        $node = array();
        foreach ($seed as $key) {
            $node[$key] = fillArray($depth + 1, $max);
        }
        return $node;
    }
    return 'empty';
}

I used this build of PHP 7:

PHP 7.0.14 (cli) (built: Jan 18 2017 19:13:23) ( NTS ) Copyright (c) 1997-2016 The PHP Group Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies with Zend OPcache v7.0.14, Copyright (c) 1999-2016, by Zend Technologies

And my results were:

serialize() (wins: 999) was roughly 10.98% faster than json_encode() unserialize() (wins: 987) was roughly 33.26% faster than json_decode() unserialize() (wins: 987) was roughly 48.35% faster than array json_decode()

So clearly, serialize/unserialize is the fastest method, while json_encode/decode is the most portable.

If you consider a scenario where you read/write serialized data 10x or more often than you need to send to or receive from a non-PHP system, you are STILL better off to use serialize/unserialize and have it json_encode or json_decode prior to serialization in terms of time.

C/C++ macro string concatenation

You don't need that sort of solution for string literals, since they are concatenated at the language level, and it wouldn't work anyway because "s""1" isn't a valid preprocessor token.

[Edit: In response to the incorrect "Just for the record" comment below that unfortunately received several upvotes, I will reiterate the statement above and observe that the program fragment

#define PPCAT_NX(A, B) A ## B
PPCAT_NX("s", "1")

produces this error message from the preprocessing phase of gcc: error: pasting ""s"" and ""1"" does not give a valid preprocessing token

]

However, for general token pasting, try this:

/*
 * Concatenate preprocessor tokens A and B without expanding macro definitions
 * (however, if invoked from a macro, macro arguments are expanded).
 */
#define PPCAT_NX(A, B) A ## B

/*
 * Concatenate preprocessor tokens A and B after macro-expanding them.
 */
#define PPCAT(A, B) PPCAT_NX(A, B)

Then, e.g., both PPCAT_NX(s, 1) and PPCAT(s, 1) produce the identifier s1, unless s is defined as a macro, in which case PPCAT(s, 1) produces <macro value of s>1.

Continuing on the theme are these macros:

/*
 * Turn A into a string literal without expanding macro definitions
 * (however, if invoked from a macro, macro arguments are expanded).
 */
#define STRINGIZE_NX(A) #A

/*
 * Turn A into a string literal after macro-expanding it.
 */
#define STRINGIZE(A) STRINGIZE_NX(A)

Then,

#define T1 s
#define T2 1
STRINGIZE(PPCAT(T1, T2)) // produces "s1"

By contrast,

STRINGIZE(PPCAT_NX(T1, T2)) // produces "T1T2"
STRINGIZE_NX(PPCAT_NX(T1, T2)) // produces "PPCAT_NX(T1, T2)"

#define T1T2 visit the zoo
STRINGIZE(PPCAT_NX(T1, T2)) // produces "visit the zoo"
STRINGIZE_NX(PPCAT(T1, T2)) // produces "PPCAT(T1, T2)"

How to import and use image in a Vue single file component?

These both work for me in JavaScript and TypeScript

<img src="@/assets/images/logo.png" alt=""> 

or

 <img src="./assets/images/logo.png" alt="">

Datatables: Cannot read property 'mData' of undefined

This one drove me crazy - how to render a DataTable successfully in a .NET MVC view. This worked:

 **@model List<Student>
 @{
    ViewData["Title"] = "Index";
}
 <h2>NEW VIEW Index</h2>
 <table id="example" class="display" style="width:100%">
   <thead>
   <tr>
   <th>ID</th>
    <th>Firstname</th>
    <th>Lastname</th> 
  </tr>
  </thead>
  <tbody>
@foreach (var element in Model)
{
    <tr>
    <td>@Html.DisplayFor(m => element.ID)</td>
    <td>@Html.DisplayFor(m => element.FirstName)</td>
    <td>@Html.DisplayFor(m => element.LastName)</td>
    </tr>

}
</tbody>
</table>**

Script in JS file:

**$(document).ready(function () {
    $('#example').DataTable();
});**

JavaFX and OpenJDK

JavaFX is part of OpenJDK

The JavaFX project itself is open source and is part of the OpenJDK project.

Update Dec 2019

For current information on how to use Open Source JavaFX, visit https://openjfx.io. This includes instructions on using JavaFX as a modular library accessed from an existing JDK (such as an Open JDK installation).

The open source code repository for JavaFX is at https://github.com/openjdk/jfx.

At the source location linked, you can find license files for open JavaFX (currently this license matches the license for OpenJDK: GPL+classpath exception).

The wiki for the project is located at: https://wiki.openjdk.java.net/display/OpenJFX/Main

If you want a quick start to using open JavaFX, the Belsoft Liberica JDK distributions provide pre-built binaries of OpenJDK that (currently) include open JavaFX for a variety of platforms.

For distribution as self-contained applications, Java 14, is scheduled to implement JEP 343: Packaging Tool, which "Supports native packaging formats to give end users a natural installation experience. These formats include msi and exe on Windows, pkg and dmg on macOS, and deb and rpm on Linux.", for deployment of OpenJFX based applications with native installers and no additional platform dependencies (such as a pre-installed JDK).


Older information which may become outdated over time

Building JavaFX from the OpenJDK repository

You can build an open version of OpenJDK (including JavaFX) completely from source which has no dependencies on the Oracle JDK or closed source code.

Update: Using a JavaFX distribution pre-built from OpenJDK sources

As noted in comments to this question and in another answer, the Debian Linux distributions offer a JavaFX binary distibution based upon OpenJDK:

(currently this only works for Java 8 as far as I know).

Differences between Open JDK and Oracle JDK with respect to JavaFX

The following information was provided for Java 8. As of Java 9, VP6 encoding is deprecated for JavaFX and the Oracle WebStart/Browser embedded application deployment technology is also deprecated. So future versions of JavaFX, even if they are distributed by Oracle, will likely not include any technology which is not open source.

Oracle JDK includes some software which is not usable from the OpenJDK. There are two main components which relate to JavaFX.

  1. The ON2 VP6 video codec, which is owned by Google and Google has not open sourced.
  2. The Oracle WebStart/Browser Embedded application deployment technology.

This means that an open version of JavaFX cannot play VP6 FLV files. This is not a big loss as it is difficult to find VP6 encoders or media encoded in VP6.

Other more common video formats, such as H.264 will playback fine with an open version of JavaFX (as long as you have the appropriate codecs pre-installed on the target machine).

The lack of WebStart/Browser Embedded deployment technology is really something to do with OpenJDK itself rather than JavaFX specifically. This technology can be used to deploy non-JavaFX applications.

It would be great if the OpenSource community developed a deployment technology for Java (and other software) which completely replaced WebStart and Browser Embedded deployment methods, allowing a nice light-weight, low impact user experience for application distribution. I believe there have been some projects started to serve such a goal, but they have not yet reached a high maturity and adoption level.

Personally, I feel that WebStart/Browser Embedded deployments are legacy technology and there are currently better ways to deploy many JavaFX applications (such as self-contained applications).

Update Dec, 2019:

An open source version of WebStart for JDK 11+ has been developed and is available at https://openwebstart.com.

Who needs to create Linux OpenJDK Distributions which include JavaFX

It is up to the people which create packages for Linux distributions based upon OpenJDK (e.g. Redhat, Ubuntu etc) to create RPMs for the JDK and JRE that include JavaFX. Those software distributors, then need to place the generated packages in their standard distribution code repositories (e.g. fedora/red hat network yum repositories). Currently this is not being done, but I would be quite surprised if Java 8 Linux packages did not include JavaFX when Java 8 is released in March 2014.

Update, Dec 2019:

Now that JavaFX has been separated from most binary JDK and JRE distributions (including Oracle's distribution) and is, instead, available as either a stand-alone SDK, set of jmods or as a library dependencies available from the central Maven repository (as outlined as https://openjfx.io), there is less of a need for standard Linux OpenJDK distributions to include JavaFX.

If you want a pre-built JDK which includes JavaFX, consider the Liberica JDK distributions, which are provided for a variety of platforms.

Advice on Deployment for Substantial Applications

I advise using Java's self-contained application deployment mode.

A description of this deployment mode is:

Application is installed on the local drive and runs as a standalone program using a private copy of Java and JavaFX runtimes. The application can be launched in the same way as other native applications for that operating system, for example using a desktop shortcut or menu entry.

You can build a self-contained application either from the Oracle JDK distribution or from an OpenJDK build which includes JavaFX. It currently easier to do so with an Oracle JDK.

As a version of Java is bundled with your application, you don't have to care about what version of Java may have been pre-installed on the machine, what capabilities it has and whether or not it is compatible with your program. Instead, you can test your application against an exact Java runtime version, and distribute that with your application. The user experience for deploying your application will be the same as installing a native application on their machine (e.g. a windows .exe or .msi installed, an OS X .dmg, a linux .rpm or .deb).

Note: The self-contained application feature was only available for Java 8 and 9, and not for Java 10-13. Java 14, via JEP 343: Packaging Tool, is scheduled to again provide support for this feature from OpenJDK distributions.

Update, April 2018: Information on Oracle's current policy towards future developments

How to initialize an array in one step using Ruby?

You can do

array = ['1', '2', '3']

As others have noted, you can also initialize an array with %w notation like so:

array = %w(1 2 3)

or

array = %w[1 2 3]

Please note that in both cases each element is a string, rather than an integer. So if you want an array whose elements are integers, you should not wrap each element with apostrophes:

array_of_integers = [1, 2, 3]

Also, you don't need to put comma in between the elements (which is necessary when creating an array without this %w notation). If you do this (which I often did by mistake), as in:

wrong_array = %w(1, 2, 3)

its elements will be three strings ---- "1,", "2,", "3". So if you do:

puts wrong_array

the output will be:

1,
2,
3
=>nil

which is not what we want here.

Hope this helps to clarify the point!

AngularJS $http-post - convert binary to excel file and download

There is no way (to my knowledge) to trigger the download window in your browser from Javascript. The only way to do it is to redirect the browser to a url that streams the file to the browser.

If you can modify your REST service, you might be able to solve it by changing so the POST request doesn't respond with the binary file, but with a url to that file. That'll get you the url in Javascript instead of the binary data, and you can redirect the browser to that url, which should prompt the download without leaving the original page.

Right way to write JSON deserializer in Spring or extend it

I was trying to @Autowire a Spring-managed service into my Deserializer. Somebody tipped me off to Jackson using the new operator when invoking the serializers/deserializers. This meant no auto-wiring of Jackson's instance of my Deserializer. Here's how I was able to @Autowire my service class into my Deserializer:

context.xml

<mvc:annotation-driven>
  <mvc:message-converters>
    <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
      <property name="objectMapper" ref="objectMapper" />
    </bean>
  </mvc:message-converters>
</mvc>
<bean id="objectMapper" class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
    <!-- Add deserializers that require autowiring -->
    <property name="deserializersByType">
        <map key-type="java.lang.Class">
            <entry key="com.acme.Anchor">
                <bean class="com.acme.AnchorDeserializer" />
            </entry>
        </map>
    </property>
</bean>

Now that my Deserializer is a Spring-managed bean, auto-wiring works!

AnchorDeserializer.java

public class AnchorDeserializer extends JsonDeserializer<Anchor> {
    @Autowired
    private AnchorService anchorService;
    public Anchor deserialize(JsonParser parser, DeserializationContext context)
             throws IOException, JsonProcessingException {
        // Do stuff
    }
}

AnchorService.java

@Service
public class AnchorService {}

Update: While my original answer worked for me back when I wrote this, @xi.lin's response is exactly what is needed. Nice find!

ORA-12154: TNS:could not resolve the connect identifier specified (PLSQL Developer)

copy paste pl sql developer in program files x86 and program files both. if client is installed in other partition/drive then copy pl sql developer to that drive also. and run from pl sql developer folder instead of desktop shortcut.

ultimate solution ! chill

How do I find the parent directory in C#?

Directory.GetParent is probably a better answer, but for completeness there's a different method that takes string and returns string: Path.GetDirectoryName.

string parent = System.IO.Path.GetDirectoryName(str_directory);

onchange event for html.dropdownlist

You can do this

@Html.DropDownList("Sortby", new SelectListItem[] { new SelectListItem() 
  { 

       Text = "Newest to Oldest", Value = "0" }, new SelectListItem() { Text = "Oldest to Newest", Value = "1" } , new
       {
           onchange = @"form.submit();"
       }
})

How does the 'binding' attribute work in JSF? When and how should it be used?

each JSF component renders itself out to HTML and has complete control over what HTML it produces. There are many tricks that can be used by JSF, and exactly which of those tricks will be used depends on the JSF implementation you are using.

  • Ensure that every from input has a totaly unique name, so that when the form gets submitted back to to component tree that rendered it, it is easy to tell where each component can read its value form.
  • The JSF component can generate javascript that submitts back to the serer, the generated javascript knows where each component is bound too, because it was generated by the component.
  • For things like hlink you can include binding information in the url as query params or as part of the url itself or as matrx parameters. for examples.

    http:..../somelink?componentId=123 would allow jsf to look in the component tree to see that link 123 was clicked. or it could e htp:..../jsf;LinkId=123

The easiest way to answer this question is to create a JSF page with only one link, then examine the html output it produces. That way you will know exactly how this happens using the version of JSF that you are using.

"ORA-01438: value larger than specified precision allowed for this column" when inserting 3

You can't update with a number greater than 1 for datatype number(2,2) is because, the first parameter is the total number of digits in the number and the second one (.i.e 2 here) is the number of digits in decimal part. I guess you can insert or update data < 1. i.e. 0.12, 0.95 etc.

Please check NUMBER DATATYPE in NUMBER Datatype.

Is there any way I can define a variable in LaTeX?

I think you probably want to use a token list for this purpose: to set up the token list \newtoks\packagename to assign the name: \packagename={New Name for the package} to put the name into your output: \the\packagename.

Difference in System. exit(0) , System.exit(-1), System.exit(1 ) in Java

Zero => Everything Okay

Positive => Something I expected could potentially go wrong went wrong (bad command-line, can't find file, could not connect to server)

Negative => Something I didn't expect at all went wrong (system error - unanticipated exception - externally forced termination e.g. kill -9)

(values greater than 128 are actually negative, if you regard them as 8-bit signed binary, or twos complement)

There's a load of good standard exit-codes here

CSS vertical alignment of inline/inline-block elements

vertical-align applies to the elements being aligned, not their parent element. To vertically align the div's children, do this instead:

div > * {
    vertical-align:middle;  // Align children to middle of line
}

See: http://jsfiddle.net/dfmx123/TFPx8/1186/

NOTE: vertical-align is relative to the current text line, not the full height of the parent div. If you wanted the parent div to be taller and still have the elements vertically centered, set the div's line-height property instead of its height. Follow jsfiddle link above for an example.

Angular-cli from css to scss

A quick and easy way to perform the migration is to use the schematic NPM package schematics-scss-migrate. this package rename all css to scss file :

ng add schematics-scss-migrate

https://github.com/Teebo/scss-migrate#readme

Excel formula is only showing the formula rather than the value within the cell in Office 2010

Check the formatting (right click on cell, Format Cells). Under tab "Number" the category should be "General". If, for instance, it's "Text" anything typed in would be treated as a string rather than a formula to be interpreted.

Getting a list of files in a directory with a glob

I won't pretend to be an expert on the topic, but you should have access to both the glob and wordexp function from objective-c, no?

How do I fix MSB3073 error in my post-build event?

I faced this issue recently and surprisingly only i was having this problem and none of my team members were facing this issue when building the project code.

On debugging i found that my code directory had spacing issue , It was D:\GIT Workspace\abc\xyz.

As a quick fix i changed it to D:\GITWS\abc\xyz and it solved the problem.

Setting the default Java character encoding

In case you are using Spring Boot and want to pass the argument file.encoding in JVM you have to run it like that:

mvn spring-boot:run -Drun.jvmArguments="-Dfile.encoding=UTF-8"

this was needed for us since we were using JTwig templates and the operating system had ANSI_X3.4-1968 that we found out through System.out.println(System.getProperty("file.encoding"));

Hope this helps someone!

How do I search within an array of hashes by hash values in ruby?

this will return first match

@fathers.detect {|f| f["age"] > 35 }

Java: get greatest common divisor

If you are using Java 1.5 or later then this is an iterative binary GCD algorithm which uses Integer.numberOfTrailingZeros() to reduce the number of checks and iterations required.

public class Utils {
    public static final int gcd( int a, int b ){
        // Deal with the degenerate case where values are Integer.MIN_VALUE
        // since -Integer.MIN_VALUE = Integer.MAX_VALUE+1
        if ( a == Integer.MIN_VALUE )
        {
            if ( b == Integer.MIN_VALUE )
                throw new IllegalArgumentException( "gcd() is greater than Integer.MAX_VALUE" );
            return 1 << Integer.numberOfTrailingZeros( Math.abs(b) );
        }
        if ( b == Integer.MIN_VALUE )
            return 1 << Integer.numberOfTrailingZeros( Math.abs(a) );

        a = Math.abs(a);
        b = Math.abs(b);
        if ( a == 0 ) return b;
        if ( b == 0 ) return a;
        int factorsOfTwoInA = Integer.numberOfTrailingZeros(a),
            factorsOfTwoInB = Integer.numberOfTrailingZeros(b),
            commonFactorsOfTwo = Math.min(factorsOfTwoInA,factorsOfTwoInB);
        a >>= factorsOfTwoInA;
        b >>= factorsOfTwoInB;
        while(a != b){
            if ( a > b ) {
                a = (a - b);
                a >>= Integer.numberOfTrailingZeros( a );
            } else {
                b = (b - a);
                b >>= Integer.numberOfTrailingZeros( b );
            }
        }
        return a << commonFactorsOfTwo;
    }
}

Unit test:

import java.math.BigInteger;
import org.junit.Test;
import static org.junit.Assert.*;

public class UtilsTest {
    @Test
    public void gcdUpToOneThousand(){
        for ( int x = -1000; x <= 1000; ++x )
            for ( int y = -1000; y <= 1000; ++y )
            {
                int gcd = Utils.gcd(x, y);
                int expected = BigInteger.valueOf(x).gcd(BigInteger.valueOf(y)).intValue();
                assertEquals( expected, gcd );
            }
    }

    @Test
    public void gcdMinValue(){
        for ( int x = 0; x < Integer.SIZE-1; x++ ){
            int gcd = Utils.gcd(Integer.MIN_VALUE,1<<x);
            int expected = BigInteger.valueOf(Integer.MIN_VALUE).gcd(BigInteger.valueOf(1<<x)).intValue();
            assertEquals( expected, gcd );
        }
    }
}

Gradle finds wrong JAVA_HOME even though it's correctly set

I faced this issue when I run the following command on Ubuntu:

ionic build android

To solve this issue, I did the following steps:

ln -sf /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java /usr/lib/jvm/default-java

Add JAVA_HOME to /etc/environment:

vi /etc/environment

Add:

JAVA_HOME="/usr/lib/jvm/default-java"

After saving, read it:

source /etc/environment

Finally, you can run build command.

How to compile a c++ program in Linux?

$ g++ 1st.cpp -o 1st

$ ./1st

if you found any error then first install g++ using code as below

$ sudo apt-get install g++

then install g++ and use above run code

object==null or null==object?

For the same reason you do it in C; assignment is an expression, so you put the literal on the left so that you can't overwrite it if you accidentally use = instead of ==.

Running an Excel macro via Python?

For Python 3.7 or later,(2018-10-10), I have to combine both @Alejandro BR and SMNALLY's answer, coz @Alejandro forget to define wincl.

import os, os.path
import win32com.client
if os.path.exists('C:/Users/jz/Desktop/test.xlsm'):
    excel_macro = win32com.client.DispatchEx("Excel.Application") # DispatchEx is required in the newest versions of Python.
    excel_path = os.path.expanduser('C:/Users/jz/Desktop/test.xlsm')
    workbook = excel_macro.Workbooks.Open(Filename = excel_path, ReadOnly =1)
    excel_macro.Application.Run("test.xlsm!Module1.Macro1") # update Module1 with your module, Macro1 with your macro
    workbook.Save()
    excel_macro.Application.Quit()  
    del excel_macro

How to easily initialize a list of Tuples?

c# 7.0 lets you do this:

  var tupleList = new List<(int, string)>
  {
      (1, "cow"),
      (5, "chickens"),
      (1, "airplane")
  };

If you don't need a List, but just an array, you can do:

  var tupleList = new(int, string)[]
  {
      (1, "cow"),
      (5, "chickens"),
      (1, "airplane")
  };

And if you don't like "Item1" and "Item2", you can do:

  var tupleList = new List<(int Index, string Name)>
  {
      (1, "cow"),
      (5, "chickens"),
      (1, "airplane")
  };

or for an array:

  var tupleList = new (int Index, string Name)[]
  {
      (1, "cow"),
      (5, "chickens"),
      (1, "airplane")
  };

which lets you do: tupleList[0].Index and tupleList[0].Name

Framework 4.6.2 and below

You must install System.ValueTuple from the Nuget Package Manager.

Framework 4.7 and above

It is built into the framework. Do not install System.ValueTuple. In fact, remove it and delete it from the bin directory.

note: In real life, I wouldn't be able to choose between cow, chickens or airplane. I would be really torn.

Is the MIME type 'image/jpg' the same as 'image/jpeg'?

No, image/jpg is not the same as image/jpeg.

You should use image/jpeg. Only image/jpeg is recognised as the actual mime type for JPEG files.

See https://tools.ietf.org/html/rfc3745, https://www.w3.org/Graphics/JPEG/ .

Serving the incorrect Content-Type of image/jpg to IE can cause issues, see http://www.bennadel.com/blog/2609-internet-explorer-aborts-images-with-the-wrong-mime-type.htm.

Populating a ComboBox using C#

Simple way is:

Dictionary<string, string> dict = new Dictionary<string, string>()
{
    {"English ","En" },
    {"Italian  ","It" },
    {"Spainish  ","Sp " }
};

combo.DataSource = new BindingSource(dict, null);
combo.DisplayMember = "Key";
combo.ValueMember = "Value";

Getting selected value of a combobox

Try this:

int selectedIndex = comboBox1.SelectedIndex;
comboBox1.SelectedItem.ToString();
int selectedValue = (int)comboBox1.Items[selectedIndex];

How are software license keys generated?

The key system must have several properties:

  • very few keys must be valid
  • valid keys must not be derivable even given everything the user has.
  • a valid key on one system is not a valid key on another.
  • others

One solution that should give you these would be to use a public key signing scheme. Start with a "system hash" (say grab the macs on any NICs, sorted, and the CPU-ID info, plus some other stuff, concatenate it all together and take an MD5 of the result (you really don't want to be handling personally identifiable information if you don't have to)) append the CD's serial number and refuse to boot unless some registry key (or some datafile) has a valid signature for the blob. The user activates the program by shipping the blob to you and you ship back the signature.

Potential issues include that you are offering to sign practically anything so you need to assume someone will run a chosen plain text and/or chosen ciphertext attacks. That can be mitigated by checking the serial number provided and refusing to handle request from invalid ones as well as refusing to handle more than a given number of queries from a given s/n in an interval (say 2 per year)

I should point out a few things: First, a skilled and determined attacker will be able to bypass any and all security in the parts that they have unrestricted access to (i.e. everything on the CD), the best you can do on that account is make it harder to get illegitimate access than it is to get legitimate access. Second, I'm no expert so there could be serious flaws in this proposed scheme.

How do I delete unpushed git commits?

Don't delete it: for just one commit git cherry-pick is enough.

But if you had several commits on the wrong branch, that is where git rebase --onto shines:

Suppose you have this:

 x--x--x--x <-- master
           \
            -y--y--m--m <- y branch, with commits which should have been on master

, then you can mark master and move it where you would want to be:

 git checkout master
 git branch tmp
 git checkout y
 git branch -f master

 x--x--x--x <-- tmp
           \
            -y--y--m--m <- y branch, master branch

, reset y branch where it should have been:

 git checkout y
 git reset --hard HEAD~2 # ~1 in your case, 
                         # or ~n, n = number of commits to cancel

 x--x--x--x <-- tmp
           \
            -y--y--m--m <- master branch
                ^
                |
                -- y branch

, and finally move your commits (reapply them, making actually new commits)

 git rebase --onto tmp y master
 git branch -D tmp


 x--x--x--x--m'--m' <-- master
           \
            -y--y <- y branch

How can I use JQuery to post JSON data?

The top answer worked fine but I suggest saving your JSON data into a variable before posting it is a little bit cleaner when sending a long form or dealing with large data in general.

_x000D_
_x000D_
var Data = {_x000D_
"name":"jonsa",_x000D_
"e-mail":"[email protected]",_x000D_
"phone":1223456789_x000D_
};_x000D_
_x000D_
_x000D_
$.ajax({_x000D_
    type: 'POST',_x000D_
    url: '/form/',_x000D_
    data: Data,_x000D_
    success: function(data) { alert('data: ' + data); },_x000D_
    contentType: "application/json",_x000D_
    dataType: 'json'_x000D_
});
_x000D_
_x000D_
_x000D_

Does a "Find in project..." feature exist in Eclipse IDE?

yes, but you need to open the global search panel. to do so, press the binoculars icon on the top right corner of the IDE.

you can even filter searches by function identifiers, method scopes an etc...

  • Choose File Search for plain text search in workspace/selected projects
  • For specific expression searches, choose the relevant tab (such as Java Search which allows to search for specific identifiers)

Calculate percentage Javascript

try

var result = (35.8 / 100) * 10;

Thanks

Mapping two integers to one, in a unique and deterministic way

Say you have a 32 bit integer, why not just move A into the first 16 bit half and B into the other?

def vec_pack(vec):
    return vec[0] + vec[1] * 65536;


def vec_unpack(number):
    return [number % 65536, number // 65536];

Other than this being as space efficient as possible and cheap to compute, a really cool side effect is that you can do vector math on the packed number.

a = vec_pack([2,4])
b = vec_pack([1,2])

print(vec_unpack(a+b)) # [3, 6] Vector addition
print(vec_unpack(a-b)) # [1, 2] Vector subtraction
print(vec_unpack(a*2)) # [4, 8] Scalar multiplication

Iterating over every property of an object in javascript using Prototype?

You should iterate over the keys and get the values using square brackets.

See: How do I enumerate the properties of a javascript object?

EDIT: Obviously, this makes the question a duplicate.

"The Controls collection cannot be modified because the control contains code blocks"

I had same issue in the user control. My page that was hosting the control had comments in the head tag, I removed those comments, everything worked afterwards. Some posts also suggest removing scripts from head and placing them in the body.

Image comparison - fast algorithm

If you have a large number of images, look into a Bloom filter, which uses multiple hashes for a probablistic but efficient result. If the number of images is not huge, then a cryptographic hash like md5 should be sufficient.

how to select rows based on distinct values of A COLUMN only

Looking at your output maybe the following query can work, give it a try:

SELECT * FROM tablename
WHERE id IN
(SELECT MIN(id) FROM tablename GROUP BY EmailAddress)

This will select only one row for each distinct email address, the row with the minimum id which is what your result seems to portray

Calculating the difference between two Java date instances

public static String getDifferenceBtwTime(Date dateTime) {

    long timeDifferenceMilliseconds = new Date().getTime() - dateTime.getTime();
    long diffSeconds = timeDifferenceMilliseconds / 1000;
    long diffMinutes = timeDifferenceMilliseconds / (60 * 1000);
    long diffHours = timeDifferenceMilliseconds / (60 * 60 * 1000);
    long diffDays = timeDifferenceMilliseconds / (60 * 60 * 1000 * 24);
    long diffWeeks = timeDifferenceMilliseconds / (60 * 60 * 1000 * 24 * 7);
    long diffMonths = (long) (timeDifferenceMilliseconds / (60 * 60 * 1000 * 24 * 30.41666666));
    long diffYears = (long)(timeDifferenceMilliseconds / (1000 * 60 * 60 * 24 * 365));

    if (diffSeconds < 1) {
        return "one sec ago";
    } else if (diffMinutes < 1) {
        return diffSeconds + " seconds ago";
    } else if (diffHours < 1) {
        return diffMinutes + " minutes ago";
    } else if (diffDays < 1) {
        return diffHours + " hours ago";
    } else if (diffWeeks < 1) {
        return diffDays + " days ago";
    } else if (diffMonths < 1) {
        return diffWeeks + " weeks ago";
    } else if (diffYears < 12) {
        return diffMonths + " months ago";
    } else {
        return diffYears + " years ago";
    }
}   

How to open VMDK File of the Google-Chrome-OS bundle 2012?

WinMount provides an easiest way to mount VMDK as a virtual disk. You can read or write to the vmdk file without loading the virtual system. Here shows you how to do: http://www.winmount.com/mount_vmdk.html

How do I increment a DOS variable in a FOR /F loop?

Or you can do this without using Delay.

set /a "counter=0"

-> your for loop here

do (
   statement1
   statement2
   call :increaseby1
 )

:increaseby1
set /a "counter+=1"

keycode and charcode

I (being people myself) wrote this statement because I wanted to detect the key which the user typed on the keyboard across different browsers.

In firefox for example, characters have > 0 charCode and 0 keyCode, and keys such as arrows & backspace have > 0 keyCode and 0 charCode.

However, using this statement can be problematic as "collisions" are possible. For example, if you want to distinguish between the Delete and the Period keys, this won't work, as the Delete has keyCode = 46 and the Period has charCode = 46.

Most efficient way to concatenate strings?

Here is the fastest method I've evolved over a decade for my large-scale NLP app. I have variations for IEnumerable<T> and other input types, with and without separators of different types (Char, String), but here I show the simple case of concatenating all strings in an array into a single string, with no separator. Latest version here is developed and unit-tested on C# 7 and .NET 4.7.

There are two keys to higher performance; the first is to pre-compute the exact total size required. This step is trivial when the input is an array as shown here. For handling IEnumerable<T> instead, it is worth first gathering the strings into a temporary array for computing that total (The array is required to avoid calling ToString() more than once per element since technically, given the possibility of side-effects, doing so could change the expected semantics of a 'string join' operation).

Next, given the total allocation size of the final string, the biggest boost in performance is gained by building the result string in-place. Doing this requires the (perhaps controversial) technique of temporarily suspending the immutability of a new String which is initially allocated full of zeros. Any such controversy aside, however...

...note that this is the only bulk-concatenation solution on this page which entirely avoids an extra round of allocation and copying by the String constructor.

Complete code:

/// <summary>
/// Concatenate the strings in 'rg', none of which may be null, into a single String.
/// </summary>
public static unsafe String StringJoin(this String[] rg)
{
    int i;
    if (rg == null || (i = rg.Length) == 0)
        return String.Empty;

    if (i == 1)
        return rg[0];

    String s, t;
    int cch = 0;
    do
        cch += rg[--i].Length;
    while (i > 0);
    if (cch == 0)
        return String.Empty;

    i = rg.Length;
    fixed (Char* _p = (s = new String(default(Char), cch)))
    {
        Char* pDst = _p + cch;
        do
            if ((t = rg[--i]).Length > 0)
                fixed (Char* pSrc = t)
                    memcpy(pDst -= t.Length, pSrc, (UIntPtr)(t.Length << 1));
        while (pDst > _p);
    }
    return s;
}

[DllImport("MSVCR120_CLR0400", CallingConvention = CallingConvention.Cdecl)]
static extern unsafe void* memcpy(void* dest, void* src, UIntPtr cb);

I should mention that this code has a slight modification from what I use myself. In the original, I call the cpblk IL instruction from C# to do the actual copying. For simplicity and portability in the code here, I replaced that with P/Invoke memcpy instead, as you can see. For highest performance on x64 (but maybe not x86) you may want to use the cpblk method instead.

jump to line X in nano editor

The shortcut is: CTRL+shift+- ("shift+-" results in "_") After typing the shortcut, nano will let you to enter the line you wanna jump to, type in the line number, then press ENTR.

Do conditional INSERT with SQL?

Usually you make the thing you don't want duplicates of unique, and allow the database itself to refuse the insert.

Otherwise, you can use INSERT INTO, see How to avoid duplicates in INSERT INTO SELECT query in SQL Server?

Codeigniter $this->db->order_by(' ','desc') result is not complete

Put the line $this->db->order_by("course_name","desc"); at top of your query. Like

$this->db->order_by("course_name","desc");$this->db->select('*');
$this->db->where('tennant_id',$tennant_id);
$this->db->from('courses');
$query=$this->db->get();
return $query->result();

What do \t and \b do?

The C standard (actually C99, I'm not up to date) says:

Alphabetic escape sequences representing nongraphic characters in the execution character set are intended to produce actions on display devices as follows:

\b (backspace) Moves the active position to the previous position on the current line. [...]

\t (horizontal tab) Moves the active position to the next horizontal tabulation position on the current line. [...]

Both just move the active position, neither are supposed to write any character on or over another character. To overwrite with a space you could try: puts("foo\b \tbar"); but note that on some display devices - say a daisy wheel printer - the o will show the transparent space.

Angular.js How to change an elements css class on click and to remove all others

I only change/remove the class:

   function removeClass() {
                    var element = angular.element('#nameInput');
          element.removeClass('nameClass');
   };

How can I get client information such as OS and browser

Update: The project is EOL and not maintained anymore. He recommends switching to the Browscap project.

You can use the bitwalker useragentutils library: https://github.com/HaraldWalker/user-agent-utils. It will provide you information about the Browser (name, type, version, manufacturer, etc.) and about the OperatingSystem. A good thing about it is that it is maintained. Access the link that I have provided to see the Maven dependency that you need to add to you project in order to use it.

See below sample code that returns the browser name and browser version.

    UserAgent userAgent = UserAgent.parseUserAgentString(request.getHeader("User-Agent"));
    Browser browser = userAgent.getBrowser();

    String browserName = browser.getName();
    //or 
    // String browserName = browser.getGroup().getName();
    Version browserVersion = userAgent.getBrowserVersion();
    System.out.println("The user is using browser " + browserName + " - version " + browserVersion);

Updating the value of data attribute using jQuery

I want to change the width and height of a div. data attributes did not change it. Instead I use:

var size = $("#theme_photo_size").val().split("x");
$("#imageupload_img").width(size[0]);
$("#imageupload_img").attr("data-width", size[0]);
$("#imageupload_img").height(size[1]);
$("#imageupload_img").attr("data-height", size[1]);

be careful:

$("#imageupload_img").data("height", size[1]); //did not work

did not set it

$("#imageupload_img").attr("data-height", size[1]); // yes it worked!

this has set it.

Using set_facts and with_items together in Ansible

As mentioned in other people's comments, the top solution given here was not working for me in Ansible 2.2, particularly when also using with_items.

It appears that OP's intended approach does work now with a slight change to the quoting of item.

- set_fact: something="{{ something + [ item ] }}"
  with_items:
    - one
    - two
    - three

And a longer example where I've handled the initial case of the list being undefined and added an optional when because that was also causing me grief:

- set_fact: something="{{ something|default([]) + [ item ] }}"
  with_items:
    - one
    - two
    - three
  when: item.name in allowed_things.item_list

Scroll RecyclerView to show selected item on top

//Scroll item pos

linearLayoutManager.scrollToPositionWithOffset(pos, 0);

How do I make a Mac Terminal pop-up/alert? Applescript?

Use osascript. For example:

osascript -e 'tell app "Finder" to display dialog "Hello World"' 

Replacing “Finder” with whatever app you desire. Note if that app is backgrounded, the dialog will appear in the background too. To always show in the foreground, use “System Events” as the app:

osascript -e 'tell app "System Events" to display dialog "Hello World"'

Read more on Mac OS X Hints.

What is this spring.jpa.open-in-view=true property in Spring Boot?

The OSIV Anti-Pattern

Instead of letting the business layer decide how it’s best to fetch all the associations that are needed by the View layer, OSIV (Open Session in View) forces the Persistence Context to stay open so that the View layer can trigger the Proxy initialization, as illustrated by the following diagram.

enter image description here

  • The OpenSessionInViewFilter calls the openSession method of the underlying SessionFactory and obtains a new Session.
  • The Session is bound to the TransactionSynchronizationManager.
  • The OpenSessionInViewFilter calls the doFilter of the javax.servlet.FilterChain object reference and the request is further processed
  • The DispatcherServlet is called, and it routes the HTTP request to the underlying PostController.
  • The PostController calls the PostService to get a list of Post entities.
  • The PostService opens a new transaction, and the HibernateTransactionManager reuses the same Session that was opened by the OpenSessionInViewFilter.
  • The PostDAO fetches the list of Post entities without initializing any lazy association.
  • The PostService commits the underlying transaction, but the Session is not closed because it was opened externally.
  • The DispatcherServlet starts rendering the UI, which, in turn, navigates the lazy associations and triggers their initialization.
  • The OpenSessionInViewFilter can close the Session, and the underlying database connection is released as well.

At first glance, this might not look like a terrible thing to do, but, once you view it from a database perspective, a series of flaws start to become more obvious.

The service layer opens and closes a database transaction, but afterward, there is no explicit transaction going on. For this reason, every additional statement issued from the UI rendering phase is executed in auto-commit mode. Auto-commit puts pressure on the database server because each transaction issues a commit at end, which can trigger a transaction log flush to disk. One optimization would be to mark the Connection as read-only which would allow the database server to avoid writing to the transaction log.

There is no separation of concerns anymore because statements are generated both by the service layer and by the UI rendering process. Writing integration tests that assert the number of statements being generated requires going through all layers (web, service, DAO) while having the application deployed on a web container. Even when using an in-memory database (e.g. HSQLDB) and a lightweight webserver (e.g. Jetty), these integration tests are going to be slower to execute than if layers were separated and the back-end integration tests used the database, while the front-end integration tests were mocking the service layer altogether.

The UI layer is limited to navigating associations which can, in turn, trigger N+1 query problems. Although Hibernate offers @BatchSize for fetching associations in batches, and FetchMode.SUBSELECT to cope with this scenario, the annotations are affecting the default fetch plan, so they get applied to every business use case. For this reason, a data access layer query is much more suitable because it can be tailored to the current use case data fetch requirements.

Last but not least, the database connection is held throughout the UI rendering phase which increases connection lease time and limits the overall transaction throughput due to congestion on the database connection pool. The more the connection is held, the more other concurrent requests are going to wait to get a connection from the pool.

Spring Boot and OSIV

Unfortunately, OSIV (Open Session in View) is enabled by default in Spring Boot, and OSIV is really a bad idea from a performance and scalability perspective.

So, make sure that in the application.properties configuration file, you have the following entry:

spring.jpa.open-in-view=false

This will disable OSIV so that you can handle the LazyInitializationException the right way.

Starting with version 2.0, Spring Boot issues a warning when OSIV is enabled by default, so you can discover this problem long before it affects a production system.

How to vertical align an inline-block in a line of text?

display: inline-block is your friend you just need all three parts of the construct - before, the "block", after - to be one, then you can vertically align them all to the middle:

Working Example

(it looks like your picture anyway ;))

CSS:

p, div {
  display: inline-block; 
  vertical-align: middle;
}
p, div {
  display: inline !ie7; /* hack for IE7 and below */
}

table {
  background: #000; 
  color: #fff; 
  font-size: 16px; 
  font-weight: bold; margin: 0 10px;
}

td {
  padding: 5px; 
  text-align: center;
}

HTML:

<p>some text</p> 
<div>
  <table summary="">
  <tr><td>A</td></tr>
  <tr><td>B</td></tr>
  <tr><td>C</td></tr>
  <tr><td>D</td></tr>
  </table>
</div> 
<p>continues afterwards</p>

How do you execute an arbitrary native command from a string?

Invoke-Expression, also aliased as iex. The following will work on your examples #2 and #3:

iex $command

Some strings won't run as-is, such as your example #1 because the exe is in quotes. This will work as-is, because the contents of the string are exactly how you would run it straight from a Powershell command prompt:

$command = 'C:\somepath\someexe.exe somearg'
iex $command

However, if the exe is in quotes, you need the help of & to get it running, as in this example, as run from the commandline:

>> &"C:\Program Files\Some Product\SomeExe.exe" "C:\some other path\file.ext"

And then in the script:

$command = '"C:\Program Files\Some Product\SomeExe.exe" "C:\some other path\file.ext"'
iex "& $command"

Likely, you could handle nearly all cases by detecting if the first character of the command string is ", like in this naive implementation:

function myeval($command) {
    if ($command[0] -eq '"') { iex "& $command" }
    else { iex $command }
}

But you may find some other cases that have to be invoked in a different way. In that case, you will need to either use try{}catch{}, perhaps for specific exception types/messages, or examine the command string.

If you always receive absolute paths instead of relative paths, you shouldn't have many special cases, if any, outside of the 2 above.

What is the id( ) function used for?

id() does return the address of the object being referenced (in CPython), but your confusion comes from the fact that python lists are very different from C arrays. In a python list, every element is a reference. So what you are doing is much more similar to this C code:

int *arr[3];
arr[0] = malloc(sizeof(int));
*arr[0] = 1;
arr[1] = malloc(sizeof(int));
*arr[1] = 2;
arr[2] = malloc(sizeof(int));
*arr[2] = 3;
printf("%p %p %p", arr[0], arr[1], arr[2]);

In other words, you are printing the address from the reference and not an address relative to where your list is stored.

In my case, I have found the id() function handy for creating opaque handles to return to C code when calling python from C. Doing that, you can easily use a dictionary to look up the object from its handle and it's guaranteed to be unique.

PHP, MySQL error: Column count doesn't match value count at row 1

The number of column parameters in your insert query is 9, but you've only provided 8 values.

INSERT INTO dbname (id, Name, Description, shortDescription, Ingredients, Method, Length, dateAdded, Username) VALUES ('', '%s', '%s', '%s', '%s', '%s', '%s', '%s')

The query should omit the "id" parameter, because it is auto-generated (or should be anyway):

INSERT INTO dbname (Name, Description, shortDescription, Ingredients, Method, Length, dateAdded, Username) VALUES ('', '%s', '%s', '%s', '%s', '%s', '%s', '%s')

Windows command for file size only

Create a file named filesize.cmd (and put into folder C:\Windows\System32):

@echo %~z1

fatal error LNK1104: cannot open file 'kernel32.lib'

I just met and solved this problem by myself. My problem is a little different. I'm using visual studio on Windows 10. When I create the project, the Target Platform Version was automatically set to 10.0.15063.0. But there is no kernel32.lib for this version of SDK, neither are other necessary header files and lib files. So I modified the Target Platform Version to 8.1. And it worked.

Environment:

  • Windows 10
  • Visual Studio 2015
  • Visual C++

Solution:

  1. Open the project's Property Page;
  2. Navigate to General page;
  3. Modify Target Platform Version to the desired target platform (e.g. 8.1).

Will the IE9 WebBrowser Control Support all of IE9's features, including SVG?

WebBrowser control will use whatever version of IE you have installed, but for compatibility reasons it will render pages in IE7 Standards mode by default.

If you want to take advantage of new IE9 features, you should add the meta tag <meta http-equiv="X-UA-Compatible" content="IE=9" > inside the <head> tag of your HTML page.

This meta tag must be added before any links to CSS, JavaScript files etc that are also in your <head> to work properly though (only other <meta> tags or the <title> tag can come before it).

An alternative is to add a registry entry to:

HKLM > SOFTWARE > Microsoft > Internet Explorer > Main > FeatureControl > FEATURE_BROWSER_EMULATION

And in there add 'myApplicationName.exe' with value '9000' to force the WebBrowser control to display pages in IE9 mode. Though there are other values you can use too too, note that these docs aren't entirely accurate as it does not seem possible to get a page to render in IE 8 mode whatever value you use.

Adding the registry key to the same path in HKCU instead of HKLM will also work - this is useful as writing to HKLM requires admin privileges where as HKCU does not.

Visual Studio SignTool.exe Not Found

I have a windows 7 and installing the ClickOnce Tools was not enough.

The signtool.exe appeared after also installing the sdk:

selection in vs 2015

Custom designing EditText

enter image description here

For EditText in image above, You have to create two xml files in res-->drawable folder. First will be "bg_edittext_focused.xml" paste the lines of code in it

<?xml version="1.0" encoding="utf-8"?>
    <shape xmlns:android="http://schemas.android.com/apk/res/android" >
        <solid android:color="#FFFFFF" />
        <stroke
            android:width="2dip"
            android:color="#F6F6F6" />
        <corners android:radius="2dip" />
        <padding
            android:bottom="7dip"
            android:left="7dip"
            android:right="7dip"
            android:top="7dip" />
    </shape>

Second file will be "bg_edittext_normal.xml" paste the lines of code in it

<?xml version="1.0" encoding="utf-8"?>
    <shape xmlns:android="http://schemas.android.com/apk/res/android" >
        <solid android:color="#F6F6F6" />
        <stroke
            android:width="2dip"
            android:color="#F6F6F6" />
        <corners android:radius="2dip" />
        <padding
            android:bottom="7dip"
            android:left="7dip"
            android:right="7dip"
            android:top="7dip" />
    </shape>

In res-->drawable folder create another xml file with name "bg_edittext.xml" that will call above mentioned code. paste the following lines of code below in bg_edittext.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/bg_edittext_focused" android:state_focused="true"/>
    <item android:drawable="@drawable/bg_edittext_normal"/>
</selector>

Finally in res-->layout-->example.xml file in your case wherever you created your editText you'll call bg_edittext.xml as background

   <EditText
    :::::
    :::::  
    android:background="@drawable/bg_edittext"
    :::::
    :::::
    />

Why should I use a pointer rather than the object itself?

There are many benefits of using pointers to object -

  1. Efficiency (as you already pointed out). Passing objects to functions mean creating new copies of object.
  2. Working with objects from third party libraries. If your object belongs to a third party code and the authors intend the usage of their objects through pointers only (no copy constructors etc) the only way you can pass around this object is using pointers. Passing by value may cause issues. (Deep copy / shallow copy issues).
  3. if the object owns a resource and you want that the ownership should not be sahred with other objects.

How to specify different Debug/Release output directories in QMake .pro file

It's also useful to have a slightly different name for the output executable. You can't use something like:

release: Target = ProgramName
debug: Target = ProgramName_d

Why it doesn't work is not clear, but it does not. But:

CONFIG(debug, debug|release) {
    TARGET = ProgramName
} else {
    TARGET = ProgramName_d
}

This does work as long as the CONFIG += line precedes it.

How to set a single, main title above all the subplots with Pyplot?

If your subplots also have titles, you may need to adjust the main title size:

plt.suptitle("Main Title", size=16)

How to scroll to top of long ScrollView layout?

Try

mainScrollView.fullScroll(ScrollView.FOCUS_UP);

it should work.

Adding a column to an existing table in a Rails migration

Use this command at rails console

rails generate migration add_fieldname_to_tablename fieldname:string

and

rake db:migrate

to run this migration

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

I needed this command to make it work on El Capitan:

sudo security add-trust -d -r trustRoot -p basic -p codeSign -k /Library/Keychains/System.keychain ~/Desktop/gdb-cert.cer

How to hide columns in an ASP.NET GridView with auto-generated columns?

You have to perform the GridView1.Columns[i].Visible = false; after the grid has been databound.

Setting dynamic scope variables in AngularJs - scope.<some_string>

If you are using Lodash library below is the way to set a dynamic variable in the angular scope.

To set the value in the angular scope.

_.set($scope, the_string, 'life.meaning')

To get the value from the angular scope.

_.get($scope, 'life.meaning')

C# Test if user has write access to a folder

IMHO the only 100% reliable way to test if you can write to a directory is to actually write to it and eventually catch exceptions.

vi/vim editor, copy a block (not usual action)

I found the below command much more convenient. If you want to copy lines from 6 to 12 and paste from the current cursor position.

:6,12 co .

If you want to copy lines from 6 to 12 and paste from 100th line.

:6,12t100

Source: https://www.reddit.com/r/vim/comments/8i6vbd/efficient_ways_of_copying_few_lines/

How can I open multiple files using "with open" in Python?

Late answer (8 yrs), but for someone looking to join multiple files into one, the following function may be of help:

def multi_open(_list):
    out=""
    for x in _list:
        try:
            with open(x) as f:
                out+=f.read()
        except:
            pass
            # print(f"Cannot open file {x}")
    return(out)

fl = ["C:/bdlog.txt", "C:/Jts/tws.vmoptions", "C:/not.exist"]
print(multi_open(fl))

2018-10-23 19:18:11.361 PROFILE  [Stop Drivers] [1ms]
2018-10-23 19:18:11.361 PROFILE  [Parental uninit] [0ms]
...
# This file contains VM parameters for Trader Workstation.
# Each parameter should be defined in a separate line and the
...

Javascript Audio Play on click

While several answers are similar, I still had an issue - the user would click the button several times, playing the audio over itself (either it was clicked by accident or they were just 'playing'....)

An easy fix:

var music = new Audio();
function playMusic(file) {
    music.pause();
    music = new Audio(file);
    music.play();
}

Setting up the audio on load allowed 'music' to be paused every time the function is called - effectively stopping the 'noise' even if they user clicks the button several times (and there is also no need to turn off the button, though for user experience it may be something you want to do).

Requests -- how to tell if you're getting a 404

Look at the r.status_code attribute:

if r.status_code == 404:
    # A 404 was issued.

Demo:

>>> import requests
>>> r = requests.get('http://httpbin.org/status/404')
>>> r.status_code
404

If you want requests to raise an exception for error codes (4xx or 5xx), call r.raise_for_status():

>>> r = requests.get('http://httpbin.org/status/404')
>>> r.raise_for_status()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "requests/models.py", line 664, in raise_for_status
    raise http_error
requests.exceptions.HTTPError: 404 Client Error: NOT FOUND
>>> r = requests.get('http://httpbin.org/status/200')
>>> r.raise_for_status()
>>> # no exception raised.

You can also test the response object in a boolean context; if the status code is not an error code (4xx or 5xx), it is considered ‘true’:

if r:
    # successful response

If you want to be more explicit, use if r.ok:.

Read XML file using javascript

You can use below script for reading child of the above xml. It will work with IE and Mozila Firefox both.

<script type="text/javascript">

function readXml(xmlFile){

var xmlDoc;

if(typeof window.DOMParser != "undefined") {
    xmlhttp=new XMLHttpRequest();
    xmlhttp.open("GET",xmlFile,false);
    if (xmlhttp.overrideMimeType){
        xmlhttp.overrideMimeType('text/xml');
    }
    xmlhttp.send();
    xmlDoc=xmlhttp.responseXML;
}
else{
    xmlDoc = new ActiveXObject("Microsoft.XMLDOM");
    xmlDoc.async="false";
    xmlDoc.load(xmlFile);
}
var tagObj=xmlDoc.getElementsByTagName("marker");
var typeValue = tagObj[0].getElementsByTagName("type")[0].childNodes[0].nodeValue;
var titleValue = tagObj[0].getElementsByTagName("title")[0].childNodes[0].nodeValue;
}
</script>

How to resolve the error on 'react-native start'

This is caused by node v12.11.0 due to the way it deals regular location there two ways to solve this problem

Method I

You can downgrade to node v12.10.0 this will apply the correct way to deal with parsing error

Method II

You can correctly terminate the regular expression in you case by changing the file located a:

\node_modules\metro-config\src\defaults\blacklist.js

From:

var sharedBlacklist = [
  /node_modules[/\\]react[/\\]dist[/\\].*/,
  /website\/node_modules\/.*/,
  /heapCapture\/bundle\.js/,
  /.*\/__tests__\/.*/
];

To:

 var sharedBlacklist = [
  /node_modules[\/\\]react[\/\\]dist[\/\\].*/,
  /website\/node_modules\/.*/,
  /heapCapture\/bundle\.js/,
  /.*\/__tests__\/.*/
];

convert double to int

I think the best way is Convert.ToInt32.

How to order citations by appearance using BibTeX?

You answered your own question---unsrt is to be used when you want references to ne listed in the order of appeareance.

But you might also want to have a look at natbib, an extremely flexible citation package. I can not imagine living without it.

Refresh certain row of UITableView based on Int in Swift

You can create an NSIndexPath using the row and section number then reload it like so:

let indexPath = NSIndexPath(forRow: rowNumber, inSection: 0)
tableView.reloadRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Top)

In this example, I've assumed that your table only has one section (i.e. 0) but you may change that value accordingly.

Update for Swift 3.0:

let indexPath = IndexPath(item: rowNumber, section: 0)
tableView.reloadRows(at: [indexPath], with: .top)

Microsoft.ACE.OLEDB.12.0 provider is not registered

I've got the same error on a fully updated Windows Vista Family 64bit with a .NET application that I've compiled to 32 bit only - the program is installed in the programx86 folder on 64 bit machines. It fails with this error message even with 2007 access database provider installed, with/wiothout the SP2 of the same installed, IIS installed and app pool set for 32bit app support... yes I've tried every solution everywhere and still no success.

I switched my app to ACE OLE DB.12.0 because JET4.0 was failing on 64bit machines - and it's no better :-/ The most promising thread I've found was this:

http://ellisweb.net/2010/01/connecting-to-excel-and-access-files-using-net-on-a-64-bit-server/

but when you try to install the 64 bit "2010 Office System Driver Beta: Data Connectivity Components" it tells you that you can't install the 64 bit version without uninstalling all 32bit office applications... and installing the 32 bit version of 2010 Office System Driver Beta: Data Connectivity Components doesn't solve the initial problem, even with "Microsoft.ACE.OLEDB.12.0" as provider instead of "Microsoft.ACE.OLEDB.14.0" which that page (and others) recommend.

My next attempt will be to follow this post:

The issue is due to the wrong flavor of OLEDB32.DLL and OLEDB32r.DLL being registered on the server. If the 64 bit versions are registered, they need to be unregistered, and then the 32 bit versions registered instead. To fix this, unregister the versions located in %Program Files%/Common Files/System/OLE DB. Then register the versions at the same path but in the %Program Files (x86)% directory.

Has anyone else had so much trouble with both JET4.0 and OLEDB ACE providers on 64 bit machines? Has anyone found a solution if none of the others work?

Multiple -and -or in PowerShell Where-Object statement

By wrapping your comparisons in {} in your first example you are creating ScriptBlocks; so the PowerShell interpreter views it as Where-Object { <ScriptBlock> -and <ScriptBlock> }. Since the -and operator operates on boolean values, PowerShell casts the ScriptBlocks to boolean values. In PowerShell anything that is not empty, zero or null is true. The statement then looks like Where-Object { $true -and $true } which is always true.

Instead of using {}, use parentheses ().

Also you want to use -eq instead of -match since match uses regex and will be true if the pattern is found anywhere in the string (try: 'xlsx' -match 'xls').

Invoke-Command -computername SERVERNAME { 
    Get-ChildItem -path E:\dfsroots\datastore2\public | 
        Where-Object {($_.extension -eq ".xls" -or $_.extension -eq ".xlk") -and ($_.creationtime -ge "06/01/2014")}
}

A better option is to filter the extensions at the Get-ChildItem command.

Invoke-Command -computername SERVERNAME { 
    Get-ChildItem -path E:\dfsroots\datastore2\public\* -Include *.xls, *.xlk | 
        Where-Object {$_.creationtime -ge "06/01/2014"}
}

How do I change the default application icon in Java?

Try This write after

initcomponents();

setIconImage(Toolkit.getDefaultToolkit().getImage(getClass().getResource("Your image address")));

JavaScript null check

Q: The function was called with no arguments, thus making data an undefined variable, and raising an error on data != null.

A: Yes, data will be set to undefined. See section 10.5 Declaration Binding Instantiation of the spec. But accessing an undefined value does not raise an error. You're probably confusing this with accessing an undeclared variable in strict mode which does raise an error.

Q: The function was called specifically with null (or undefined), as its argument, in which case data != null already protects the inner code, rendering && data !== undefined useless.

Q: The function was called with a non-null argument, in which case it will trivially pass both data != null and data !== undefined.

A: Correct. Note that the following tests are equivalent:

data != null
data != undefined
data !== null && data !== undefined

See section 11.9.3 The Abstract Equality Comparison Algorithm and section 11.9.6 The Strict Equality Comparison Algorithm of the spec.

How can I detect if a selector returns null?

I like to do something like this:

$.fn.exists = function(){
    return this.length > 0 ? this : false;
}

So then you can do something like this:

var firstExistingElement = 
    $('#iDontExist').exists() ||      //<-returns false;
    $('#iExist').exists() ||          //<-gets assigned to the variable 
    $('#iExistAsWell').exists();      //<-never runs

firstExistingElement.doSomething();   //<-executes on #iExist

http://jsfiddle.net/vhbSG/

ld cannot find -l<library>

I had a similar problem with another library and the reason why it didn't found it, was that I didn't run the make install (after running ./configure and make) for that library. The make install may require root privileges (in this case use: sudo make install). After running the make install you should have the so files in the correct folder, i.e. here /usr/local/lib and not in the folder mentioned by you.

Why is this printing 'None' in the output?

Because there are two print statements. First is inside function and second is outside function. When function not return any thing that time it return None value.

Use return statement at end of function to return value.

e.g.:

Return None value.

>>> def test1():
...    print "In function."
... 
>>> a = test1()
In function.
>>> print a
None
>>> 
>>> print test1()
In function.
None
>>>
>>> test1()
In function.
>>> 

Use return statement

>>> def test():
...   return "ACV"
... 
>>> print test()
ACV
>>> 
>>> a = test()
>>> print a
ACV
>>> 

Adding elements to object

Adding new key/pair elements into the original object:

const obj = { a:1, b:2 }
const add = { c:3, d:4, e: ['x','y','z'] }

Object.entries(add).forEach(([key,value]) => { obj[key] = value })

obj new value:

{a: 1, b: 2, c: 3, d: 4, e: ["x", "y", "z"] }

Good Free Alternative To MS Access

VistaDB is the only alternative if you going to run your website at shared hosting (almost all of them won't let you run your websites under Full Trust mode) and also if you need simple x-copy deployment enabled website.

Is the Scala 2.8 collections library a case of "the longest suicide note in history"?

Is this going to put people off coming to Scala?

I don't think it is the main factor that will affect how popular Scala will become, because Scala has a lot of power and its syntax is not as foreign to a Java/C++/PHP programmer as Haskell, OCaml, SML, Lisps, etc..

But I do think Scala's popularity will plateau at less than where Java is today, because I also think the next mainstream language must be much simplified, and the only way I see to get there is pure immutability, i.e. declarative like HTML, but Turing complete. However, I am biased because I am developing such a language, but I only did so after ruling out over a several month study that Scala could not suffice for what I needed.

Is this going to give Scala a bad name in the commercial world as an academic plaything that only dedicated PhD students can understand? Are CTOs and heads of software going to get scared off?

I don't think Scala's reputation will suffer from the Haskell complex. But I think that some will put off learning it, because for most programmers, I don't yet see a use case that forces them to use Scala, and they will procrastinate learning about it. Perhaps the highly-scalable server side is the most compelling use case.

And, for the mainstream market, first learning Scala is not a "breath of fresh air", where one is writing programs immediately, such as first using HTML or Python. Scala tends to grow on you, after one learns all the details that one stumbles on from the start. However, maybe if I had read Programming in Scala from the start, my experience and opinion of the learning curve would have been different.

Was the library re-design a sensible idea?

Definitely.

If you're using Scala commercially, are you worried about this? Are you planning to adopt 2.8 immediately or wait to see what happens?

I am using Scala as the initial platform of my new language. I probably wouldn't be building code on Scala's collection library if I was using Scala commercially otherwise. I would create my own category theory based library, since the one time I looked, I found Scalaz's type signatures even more verbose and unwieldy than Scala's collection library. Part of that problem perhaps is Scala's way of implementing type classes, and that is a minor reason I am creating my own language.


I decided to write this answer, because I wanted to force myself to research and compare Scala's collection class design to the one I am doing for my language. Might as well share my thought process.

The 2.8 Scala collections use of a builder abstraction is a sound design principle. I want to explore two design tradeoffs below.

  1. WRITE-ONLY CODE: After writing this section, I read Carl Smotricz's comment which agrees with what I expect to be the tradeoff. James Strachan and davetron5000's comments concur that the meaning of That (it is not even That[B]) and the mechanism of the implicit is not easy to grasp intuitively. See my use of monoid in issue #2 below, which I think is much more explicit. Derek Mahar's comment is about writing Scala, but what about reading the Scala of others that is not "in the common cases".

    One criticism I have read about Scala, is that it is easier to write it, than read the code that others have written. And I find this to be occasionally true for various reasons (e.g. many ways to write a function, automatic closures, Unit for DSLs, etc), but I am undecided if this is major factor. Here the use of implicit function parameters has pluses and minuses. On the plus side, it reduces verbosity and automates selection of the builder object. In Odersky's example the conversion from a BitSet, i.e. Set[Int], to a Set[String] is implicit. The unfamiliar reader of the code might not readily know what the type of collection is, unless they can reason well about the all the potential invisible implicit builder candidates which might exist in the current package scope. Of course, the experienced programmer and the writer of the code will know that BitSet is limited to Int, thus a map to String has to convert to a different collection type. But which collection type? It isn't specified explicitly.

  2. AD-HOC COLLECTION DESIGN: After writing this section, I read Tony Morris's comment and realized I am making nearly the same point. Perhaps my more verbose exposition will make the point more clear.

    In "Fighting Bit Rot with Types" Odersky & Moors, two use cases are presented. They are the restriction of BitSet to Int elements, and Map to pair tuple elements, and are provided as the reason that the general element mapping function, A => B, must be able to build alternative destination collection types. However, afaik this is flawed from a category theory perspective. To be consistent in category theory and thus avoid corner cases, these collection types are functors, in which each morphism, A => B, must map between objects in the same functor category, List[A] => List[B], BitSet[A] => BitSet[B]. For example, an Option is a functor that can be viewed as a collection of sets of one Some( object ) and the None. There is no general map from Option's None, or List's Nil, to other functors which don't have an "empty" state.

    There is a tradeoff design choice made here. In the design for collections library of my new language, I chose to make everything a functor, which means if I implement a BitSet, it needs to support all element types, by using a non-bit field internal representation when presented with a non-integer type parameter, and that functionality is already in the Set which it inherits from in Scala. And Map in my design needs to map only its values, and it can provide a separate non-functor method for mapping its (key,value) pair tuples. One advantage is that each functor is then usually also an applicative and perhaps a monad too. Thus all functions between element types, e.g. A => B => C => D => ..., are automatically lifted to the functions between lifted applicative types, e.g. List[A] => List[B] => List[C] => List[D] => .... For mapping from a functor to another collection class, I offer a map overload which takes a monoid, e.g. Nil, None, 0, "", Array(), etc.. So the builder abstraction function is the append method of a monoid and is supplied explicitly as a necessary input parameter, thus with no invisible implicit conversions. (Tangent: this input parameter also enables appending to non-empty monoids, which Scala's map design can't do.) Such conversions are a map and a fold in the same iteration pass. Also I provide a traversable, in the category sense, "Applicative programming with effects" McBride & Patterson, which also enables map + fold in a single iteration pass from any traversable to any applicative, where most every collection class is both. Also the state monad is an applicative and thus is a fully generalized builder abstraction from any traversable.

    So afaics the Scala collections is "ad-hoc" in the sense that it is not grounded in category theory, and category theory is the essense of higher-level denotational semantics. Although Scala's implicit builders are at first appearance "more generalized" than a functor model + monoid builder + traversable -> applicative, they are afaik not proven to be consistent with any category, and thus we don't know what rules they follow in the most general sense and what the corner cases will be given they may not obey any category model. It is simply not true that adding more variables makes something more general, and this was one of huge benefits of category theory is it provides rules by which to maintain generality while lifting to higher-level semantics. A collection is a category.

    I read somewhere, I think it was Odersky, as another justification for the library design, is that programming in a pure functional style has the cost of limited recursion and speed where tail recursion isn't used. I haven't found it difficult to employ tail recursion in every case that I have encountered so far.


Additionally I am carrying in my mind an incomplete idea that some of Scala's tradeoffs are due to trying to be both an mutable and immutable language, unlike for example Haskell or the language I am developing. This concurs with Tony Morris's comment about for comprehensions. In my language, there are no loops and no mutable constructs. My language will sit on top of Scala (for now) and owes much to it, and this wouldn't be possible if Scala didn't have the general type system and mutability. That might not be true though, because I think Odersky & Moors ("Fighting Bit Rot with Types") are incorrect to state that Scala is the only OOP language with higher-kinds, because I verified (myself and via Bob Harper) that Standard ML has them. Also appears SML's type system may be equivalently flexible (since 1980s), which may not be readily appreciated because the syntax is not so much similar to Java (and C++/PHP) as Scala. In any case, this isn't a criticism of Scala, but rather an attempt to present an incomplete analysis of tradeoffs, which is I hope germane to the question. Scala and SML don't suffer from Haskell's inability to do diamond multiple inheritance, which is critical and I understand is why so many functions in the Haskell Prelude are repeated for different types.