Programs & Examples On #Mime types

A MIME type after MIME (Multipurpose Internet Mail Extensions) is a two-part identifier for file formats on the Internet.

Debug message "Resource interpreted as other but transferred with MIME type application/javascript"

I don't think it is a bug, Try adding the MIME type to your .htaccess file For instance, put or add the following content to your .htaccess file (which should be in the same place of your .js or above folders)

AddType application/x-javascript .js

This solved my tree "Resource interpreted as other but transfered ... " warnings. Everytime you have that kind of warning it means you don't have enough info in your .htaccess file.

BTW1: Since you are modifying .htaccess file, make sure you restart your server.

BTW2: I also could clear same warnings for GIF files in Safari 4 with this:

AddType image/gif .gif

BTW3: For other file types: see w3schools list or htaccess-guide

Interface/enum listing standard mime-type constants

If you are using Spring Framework then there is a MediaType class for common content types:


What is a correct MIME type for .docx, .pptx, etc.?

To load a .docx file:

    if let htmlFile = Bundle.main.path(forResource: "fileName", ofType: "docx") {
        let url = URL(fileURLWithPath: htmlFile)
            let data = try Data(contentsOf: url)
            self.webView.load(data, mimeType: "application/vnd.openxmlformats-officedocument.wordprocessingml.document", textEncodingName: "UTF-8", baseURL: url)

Add MIME mapping in web.config for IIS Express

Putting it in the "web.config" works fine. The problem was that I got the MIME type wrong. Instead of font/x-woff or font/x-font-woff it must be application/font-woff:

    <remove fileExtension=".woff" />
    <mimeMap fileExtension=".woff" mimeType="application/font-woff" />

See also this answer regarding the MIME type:

Update 4/10/2013

Spec is now a recommendation and the MIME type is officially: application/font-woff

How to determine MIME type of file in android?

you have multiple choice to get extension of file:like: 1-String filename = uri.getLastPathSegment(); see this link

2-you can use this code also

 filePath .substring(filePath.lastIndexOf(".")+1);

but this not good aproch. 3-if you have URI of file then use this Code

String[] projection = { MediaStore.MediaColumns.DATA,
MediaStore.MediaColumns.MIME_TYPE };

4-if you have URL then use this code:

 public static String getMimeType(String url) {
String type = null;
String extension = MimeTypeMap.getFileExtensionFromUrl(url);
if (extension != null) { 

  type = MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);

return type;

enjoy your code:)

What MIME type should I use for CSV?

For anyone struggling with Google API mimeType for *.csv files. I have found the list of MIME types for google api docs files (look at snipped result)

<table border="1"><thead><tr><th>Google Doc Format</th><th>Conversion Format</th><th>Corresponding MIME type</th></tr></thead><tbody><tr><td>Documents</td><td>HTML</td><td>text/html</td></tr><tr></tr><tr><td></td><td>HTML (zipped)</td><td>application/zip</td></tr><tr><td></td><td>Plain text</td><td>text/plain</td></tr><tr><td></td><td>Rich text</td><td>application/rtf</td></tr><tr><td></td><td>Open Office doc</td><td>application/vnd.oasis.opendocument.text</td></tr><tr><td></td><td>PDF</td><td>application/pdf</td></tr><tr><td></td><td>MS Word document</td><td>application/vnd.openxmlformats-officedocument.wordprocessingml.document</td></tr><tr><td></td><td>EPUB</td><td>application/epub+zip</td></tr><tr><td>Spreadsheets</td><td>MS Excel</td><td>application/vnd.openxmlformats-officedocument.spreadsheetml.sheet</td></tr><tr><td></td><td>Open Office sheet</td><td>application/x-vnd.oasis.opendocument.spreadsheet</td></tr><tr><td></td><td>PDF</td><td>application/pdf</td></tr><tr><td></td><td>CSV (first sheet only)</td><td>text/csv</td></tr><tr><td></td><td>TSV (first sheet only)</td><td>text/tab-separated-values</td></tr><tr><td></td><td>HTML (zipped)</td><td>application/zip</td></tr><tr></tr><tr><td>Drawings</td><td>JPEG</td><td>image/jpeg</td></tr><tr><td></td><td>PNG</td><td>image/png</td></tr><tr><td></td><td>SVG</td><td>image/svg+xml</td></tr><tr><td></td><td>PDF</td><td>application/pdf</td></tr><tr><td>Presentations</td><td>MS PowerPoint</td><td>application/vnd.openxmlformats-officedocument.presentationml.presentation</td></tr><tr><td></td><td>Open Office presentation</td><td>application/vnd.oasis.opendocument.presentation</td></tr><tr></tr><tr><td></td><td>PDF</td><td>application/pdf</td></tr><tr><td></td><td>Plain text</td><td>text/plain</td></tr><tr><td>Apps Scripts</td><td>JSON</td><td>application/</td></tr></tbody></table>

Source here: the table under: "Google Doc formats and supported export MIME types map to each other as follows"

There is also another list

<table border="1"><thead><tr><th>MIME Type</th><th>Description</th></tr></thead><tbody><tr><td><code><span>application/vnd.<wbr>google-apps.<wbr>audio</span></code></td><td></td></tr><tr><td><code><span>application/vnd.<wbr>google-apps.<wbr>document</span></code></td><td>Google Docs</td></tr><tr><td><code><span>application/vnd.<wbr>google-apps.<wbr>drawing</span></code></td><td>Google Drawing</td></tr><tr><td><code><span>application/vnd.<wbr>google-apps.<wbr>file</span></code></td><td>Google Drive file</td></tr><tr><td><code><span>application/vnd.<wbr>google-apps.<wbr>folder</span></code></td><td>Google Drive folder</td></tr><tr><td><code><span>application/vnd.<wbr>google-apps.<wbr>form</span></code></td><td>Google Forms</td></tr><tr><td><code><span>application/vnd.<wbr>google-apps.<wbr>fusiontable</span></code></td><td>Google Fusion Tables</td></tr><tr><td><code><span>application/vnd.<wbr>google-apps.<wbr>map</span></code></td><td>Google My Maps</td></tr><tr><td><code><span>application/vnd.<wbr>google-apps.<wbr>photo</span></code></td><td></td></tr><tr><td><code><span>application/vnd.<wbr>google-apps.<wbr>presentation</span></code></td><td>Google Slides</td></tr><tr><td><code><span>application/vnd.<wbr>google-apps.<wbr>script</span></code></td><td>Google Apps Scripts</td></tr><tr><td><code><span>application/vnd.<wbr>google-apps.<wbr>site</span></code></td><td>Google Sites</td></tr><tr><td><code><span>application/vnd.<wbr>google-apps.<wbr>spreadsheet</span></code></td><td>Google Sheets</td></tr><tr><td><code><span>application/vnd.<wbr>google-apps.<wbr>unknown</span></code></td><td></td></tr><tr><td><code><span>application/vnd.<wbr>google-apps.<wbr>video</span></code></td><td></td></tr><tr><td><code><span>application/vnd.<wbr>google-apps.<wbr>drive-sdk</span></code></td><td>3rd party shortcut</td></tr></tbody></table>

Source here:

But the first one was more helpful for my use case..

Happy coding ;)

Right mime type for SVG images with fonts embedded

There's only one registered mediatype for SVG, and that's the one you listed, image/svg+xml. You can of course serve SVG as XML too, though browsers tend to behave differently in some scenarios if you do, for example I've seen cases where SVG used in CSS backgrounds fail to display unless served with the image/svg+xml mediatype.

.rar, .zip files MIME Type

For upload:

An official list of mime types can be found at The Internet Assigned Numbers Authority (IANA) . According to their list Content-Type header for zip is application/zip.

The media type for rar files is not officially registered at IANA but the unofficial commonly used mime-type value is application/x-rar-compressed.

application/octet-stream means as much as: "I send you a file stream and the content of this stream is not specified" (so it is true that it can be a zip or rar file as well). The server is supposed to detect what the actual content of the stream is.

Note: For upload it is not safe to rely on the mime type set in the Content-Type header. The header is set on the client and can be set to any random value. Instead you can use the php file info functions to detect the file mime-type on the server.

For download:

If you want to download a zip file and nothing else you should only set one single Accept header value. Any additional values set will be used as a fallback in case the server cannot satisfy your in the Accept header requested mime-type.

According to the WC3 specifications this:

application/zip, application/octet-stream 

will be intrepreted as: "I prefer a application/zip mime-type, but if you cannot deliver this an application/octet-stream (a file stream) is also fine".

So only a single:


Will guarantee you a zip file (or a 406 - Not Acceptable response in case the server is unable to satisfy your request).

Correct mime type for .mp4

video/mp4should be used when you have video content in your file. If there is none, but there is audio, you should use audio/mp4. If no audio and no video is used, for instance if the file contains only a subtitle track or a metadata track, the MIME should be application/mp4. Also, as a server, you should try to include the codecs or profiles parameters as defined in RFC6381, as this will help clients determine if they can play the file, prior to downloading it.

Correct MIME Type for favicon.ico?

When you're serving an .ico file to be used as a favicon, it doesn't matter. All major browsers recognize both mime types correctly. So you could put:

<!-- IE -->
<link rel="shortcut icon" type="image/x-icon" href="favicon.ico" />
<!-- other browsers -->
<link rel="icon" type="image/x-icon" href="favicon.ico" />

or the same with image/, and it will work with all browsers.

Note: There is no IANA specification for the MIME-type image/x-icon, so it does appear that it is a little more unofficial than image/

The only case in which there is a difference is if you were trying to use an .ico file in an <img> tag (which is pretty unusual). Based on previous testing, some browsers would only display .ico files as images when they were served with the MIME-type image/x-icon. More recent tests show: Chromium, Firefox and Edge are fine with both content types, IE11 is not. If you can, just avoid using ico files as images, use png.

What is a MIME type?

MIME stands for Multipurpose Internet Mail Extensions. It's a way of identifying files on the Internet according to their nature and format.

For example, using the Content-type header value defined in a HTTP response, the browser can open the file with the proper extension/plugin.

Internet Media Type (also Content-type) is the same as a MIME type. MIME types were originally created for emails sent using the SMTP protocol. Nowadays, this standard is used in a lot of other protocols, hence the new naming convention "Internet Media Type".

A MIME type is a string identifier composed of two parts: a type and a subtype.

  • The "type" refers to a logical grouping of many MIME types that are closely related to each other; it's no more than a high level category.
  • "subtypes" are specific to one file type within the "type".

The x- prefix of a MIME subtype simply means that it's non-standard.
The vnd prefix means that the MIME value is vendor specific.


Proper MIME type for .woff2 fonts

In IIS you can declare the mime type for WOFF2 font files by adding the following to your project's web.config:

    <remove fileExtension=".woff2" />
    <mimeMap fileExtension=".woff2" mimeType="font/woff2" />

Update: The mime type may be changing according to the latest W3C Editor's Draft WOFF2 spec. See Appendix A: Internet Media Type Registration section 6.5. WOFF 2.0 which states the latest proposed format is font/woff2

What does "Content-type: application/json; charset=utf-8" really mean?

I was using HttpClient and getting back response header with content-type of application/json, I lost characters such as foreign languages or symbol that used unicode since HttpClient is default to ISO-8859-1. So, be explicit as possible as mentioned by @WesternGun to avoid any possible problem.

There is no way handle that due to server doesn't handle requested-header charset (method.setRequestHeader("accept-charset", "UTF-8");) for me and I had to retrieve response data as draw bytes and convert it into String using UTF-8. So, it is recommended to be explicit and avoid assumption of default value.

Stylesheet not loaded because of MIME-type

Remove rel="stylesheet" and add type="text/html". So it will look like this -

<link  href="styles.css" type="text/html" />

Which mime type should I use for mp3

I had a problem with mime types and where making tests for few file types. It looks like each browser sends it's variation of a mime type for a specific file. I was trying to upload mp3 and zip files with open source php class, that what I have found:

  • Firefox (mp3): audio/mpeg
  • Firefox (zip): application/zip
  • Chrome (mp3): audio/mp3
  • Chrome (zip): application/octet-stream
  • Opera (mp3): audio/mp3
  • Opera (zip): application/octet-stream
  • IE (mp3): audio/mpeg
  • IE (zip): application/x-zip-compressed

So if you need several file types to upload, you better make some tests so that every browser could upload a file and pass mime type check.

Why write <script type="text/javascript"> when the mime type is set by the server?

Because, at least in HTML 4.01 and XHTML 1(.1), the type attribute for <script> elements is required.

In HTML 5, type is no longer required.

In fact, while you should use text/javascript in your HTML source, many servers will send the file with Content-type: application/javascript. Read more about these MIME types in RFC 4329.

Notice the difference between RFC 4329, that marked text/javascript as obsolete and recommending the use of application/javascript, and the reality in which some browsers freak out on <script> elements containing type="application/javascript" (in HTML source, not the HTTP Content-type header of the file that gets send). Recently, there was a discussion on the WHATWG mailing list about this discrepancy (HTML 5's type defaults to text/javascript), read these messages with subject Will you consider about RFC 4329?

HTTP Error 404.3-Not Found in IIS 7.5

You should install IIS sub components from

Control Panel -> Programs and Features -> Turn Windows features on or off

Internet Information Services has subsection World Wide Web Services / Application Development Features

There you must check ASP.NET (.NET Extensibility, ISAPI Extensions, ISAPI Filters will be selected automatically). Double check that specific versions are checked. Under Windows Server 2012 R2, these options are split into 4 & 4.5.

Run from cmd:

%windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_regiis.exe -ir

Finally check in IIS manager, that your application uses application pool with .NET framework version v4.0.

Also, look at this answer.

How to check file MIME type with javascript before upload?

For anyone who's looking to not implement this themselves, Sindresorhus has create a utility that works in the browser and has the header-to-mime mappings for most documents you could want.

You could combine's suggestion of only reading in the first X bytes to avoid loading everything into memory with using this utility (example in es6):

import fileType from 'file-type'; // or wherever you load the dependency

const blob = file.slice(0, fileType.minimumBytes);

const reader = new FileReader();
reader.onloadend = function(e) {
  if ( !== FileReader.DONE) {

  const bytes = new Uint8Array(;
  const { ext, mime } = fileType.fromBuffer(bytes);

  // ext is the desired extension and mime is the mimetype

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

For those it might help, I use this list as a reference to define my content-type when I have to deal with images on my app.

It says that jpg extension can be declared with Content-type : image/jpeg

There isn't any image/jpg attribute for content-type.

What is correct content-type for excel files?

Do keep in mind that the file.getContentType could also output application/octet-stream instead of the required application/vnd.openxmlformats-officedocument.spreadsheetml.sheet when you try to upload the file that is already open.

Using .NET, how can you find the mime type of a file based on the file signature not the extension

I think the right answer is a combination of Steve Morgan's and Serguei's answers. That's how Internet Explorer does it. The pinvoke call to FindMimeFromData works for only 26 hard-coded mime types. Also, it will give ambigous mime types (such as text/plain or application/octet-stream) even though there may exist a more specific, more appropriate mime type. If it fails to give a good mime type, you can go to the registry for a more specific mime type. The server registry could have more up-to-date mime types.

Refer to:

How can I find out a file's MIME type (Content-Type)?

one of the other tool (besides file) you can use is xdg-mime

eg xdg-mime query filetype <file>

if you have yum,

yum install xdg-utils.noarch

An example comparison of xdg-mime and file on a Subrip(subtitles) file

$ xdg-mime query filetype

$ file --mime-type text/plain

in the above file only show it as plain text.

When to use the JavaScript MIME type application/javascript instead of text/javascript?

In theory, according to RFC 4329, application/javascript.

The reason it is supposed to be application is not anything to do with whether the type is readable or executable. It's because there are custom charset-determination mechanisms laid down by the language/type itself, rather than just the generic charset parameter. A subtype of text should be capable of being transcoded by a proxy to another charset, changing the charset parameter. This is not true of JavaScript because:

a. the RFC says user-agents should be doing BOM-sniffing on the script to determine type (I'm not sure if any browsers actually do this though);

b. browsers use other information—the including page's encoding and in some browsers the script charset attribute—to determine the charset. So any proxy that tried to transcode the resource would break its users. (Of course in reality no-one ever uses transcoding proxies anyway, but that was the intent.)

Therefore the exact bytes of the file must be preserved exactly, which makes it a binary application type and not technically character-based text.

For the same reason, application/xml is officially preferred over text/xml: XML has its own in-band charset signalling mechanisms. And everyone ignores application for XML, too.

text/javascript and text/xml may not be the official Right Thing, but there are what everyone uses today for compatibility reasons, and the reasons why they're not the right thing are practically speaking completely unimportant.

What Content-Type value should I send for my XML sitemap?

Other answers here address the general question of what the proper Content-Type for an XML response is, and conclude (as with What's the difference between text/xml vs application/xml for webservice response) that both text/xml and application/xml are permissible. However, none address whether there are any rules specific to sitemaps.

Answer: there aren't. The sitemap spec is, and using Google site: searches you can confirm that it does not contain the words or phrases mime, mimetype, content-type, application/xml, or text/xml anywhere. In other words, it is entirely silent on the topic of what Content-Type should be used for serving sitemaps.

In the absence of any commentary in the sitemap spec directly addressing this question, we can safely assume that the same rules apply as when choosing the Content-Type of any other XML document - i.e. that it may be either text/xml or application/xml.

Chrome says "Resource interpreted as script but transferred with MIME type text/plain.", what gives?

This has nothing to do with jQuery or any quirk of client-side script code. It is a server-side issue: The server(-side application) is not sending the expected HTTP Content-Type header field value for the client-side script resource. This happens if the Web server is insufficiently configured, misconfigured, or a server-side application (e. g., PHP) is generating the client-side script resource.

Proper MIME media types for ECMAScript implementations like JavaScript include:

  • text/javascript (registered as obsolete, not deprecated; but still valid, and supported best)
  • text/ecmascript (registered as obsolete, not deprecated; but still valid)
  • application/javascript
  • application/ecmascript

They do not include application/x-javascript, as the MIME media types listed above are the ones registered in the standards tree by now (so there is no need, and there should be no want, to use experimental ones anymore). Cf. RFC 4329, "Scripting Media Types" (2005 CE) and my Test Case: Support for Scripting Media Types.

One solution is to configure the server if possible, as already recommended. For Apache, this can be as simple as adding the directive

AddType text/javascript .js

(see the Apache HTTP Server documentation for details).

But if the client-side script resource is generated by a server-side application, like PHP, then it is necessary to set the Content-Type header field value explicitly, as the default is likely text/html:

  header('Content-Type: text/javascript; charset=UTF-8');
  // ...

(That and similar statements must come before any other output – see the PHP manual –, else the HTTP message body is considered to have begun already and it is too late to send more header fields.)

Server-side generation can happen easily to a client-side script resource even if you have plain .js files on the server, if comments are removed from them as they are served, if they are all packed into one large response (to reduce the number of requests, which can be more efficient), or they are minimized by the server-side application in any other way.

Which MIME type to use for a binary file that's specific to my program?

mimetype headers are recognised by the browser for the purpose of a (fast) possible identifying a handler to use the downloaded file as target, for example, PDF would be downloaded and your Adobe Reader program would be executed with the path of the PDF file as an argument,

If your needs are to write a browser extension to handle your downloaded file, through your operation-system, or you simply want to make you project a more 'professional looking' go ahead and select a unique mimetype for you to use, it would make no difference since the operation-system would have no handle to open it with (some browsers has few bundled-plugins, for example new Google Chrome versions has a built-in PDF-reader),

if you want to make sure the file would be downloaded have a look at this answer:

if you want to make your file type especially organised, it might be worth adding a few letters in the first few bytes of the file, for example, every JPG has this at it's file start:

if you can afford a jump of 4 or 8 bytes it could be very helpful for you in the rest of the way


File input 'accept' attribute - is it useful?

It's been a few years, and Chrome at least makes use of this attribute. This attribute is very useful from a usability standpoint as it will filter out the unnecessary files for the user, making their experience smoother. However, the user can still select "all files" from the type (or otherwise bypass the filter), thus you should always validate the file where it is actually used; If you're using it on the server, validate it there before using it. The user can always bypass any client-side scripting.

How to set MimeBodyPart ContentType to "text/html"?

Try with this:

msg.setContent(email.getBody(), "text/html; charset=ISO-8859-1");

Why does foo = filter(...) return a <filter object>, not a list?

Please see this sample implementation of filter to understand how it works in Python 3:

def my_filter(function, iterable):
    """my_filter(function or None, iterable) --> filter object

    Return an iterator yielding those items of iterable for which function(item)
    is true. If function is None, return the items that are true."""
    if function is None:
        return (item for item in iterable if item)
    return (item for item in iterable if function(item))

The following is an example of how you might use filter or my_filter generators:

>>> greetings = {'hello'}
>>> spoken = my_filter(greetings.__contains__, ('hello', 'goodbye'))
>>> print('\n'.join(spoken))

How to retrieve the dimensions of a view?

I guess this is what you need to look at: use onSizeChanged() of your view. Here is an EXTENDED code snippet on how to use onSizeChanged() to get your layout's or view's height and width dynamically

exit application when click button - iOS

exit(X), where X is a number (according to the doc) should work. But it is not recommended by Apple and won't be accepted by the AppStore. Why? Because of these guidelines (one of my app got rejected):

We found that your app includes a UI control for quitting the app. This is not in compliance with the iOS Human Interface Guidelines, as required by the App Store Review Guidelines.

Please refer to the attached screenshot/s for reference.

The iOS Human Interface Guidelines specify,

"Always Be Prepared to Stop iOS applications stop when people press the Home button to open a different application or use a device feature, such as the phone. In particular, people don’t tap an application close button or select Quit from a menu. To provide a good stopping experience, an iOS application should:

Save user data as soon as possible and as often as reasonable because an exit or terminate notification can arrive at any time.

Save the current state when stopping, at the finest level of detail possible so that people don’t lose their context when they start the application again. For example, if your app displays scrolling data, save the current scroll position."

> It would be appropriate to remove any mechanisms for quitting your app.

Plus, if you try to hide that function, it would be understood by the user as a crash.

What is the PostgreSQL equivalent for ISNULL()

Create the following function

    "is null) WHEN true THEN $2 ELSE $1 END) AS RESULT' LANGUAGE 'sql'

And it'll work.

You may to create different versions with different parameter types.

Calculate logarithm in python


Use the log10 function in the math module.

jQuery Keypress Arrow Keys

$(document).keydown(function(e) {

Keypress events do detect arrow keys, but not in all browsers. So it's better to use keydown.

These are keycodes you should be getting in your console log:

  • left = 37
  • up = 38
  • right = 39
  • down = 40

Oracle REPLACE() function isn't handling carriage-returns & line-feeds

Ahah! Cade is on the money.

An artifact in TOAD prints \r\n as two placeholder 'blob' characters, but prints a single \r also as two placeholders. The 1st step toward a solution is to use ..

REPLACE( col_name, CHR(13) || CHR(10) )

.. but I opted for the slightly more robust ..

REPLACE(REPLACE( col_name, CHR(10) ), CHR(13) )

.. which catches offending characters in any order. My many thanks to Cade.


unix sort descending order

If you only want to sort only on the 5th field then use -k5,5.

Also, use the -t command line switch to specify the delimiter to tab. Try this:

sort  -k5,5 -r -n -t \t filename

or if the above doesn't work (with the tab) this:

sort  -k5,5 -r -n -t $'\t' filename

The man page for sort states:

-t, --field-separator=SEP use SEP instead of non-blank to blank transition

Finally, this SO question Unix Sort with Tab Delimiter might be helpful.

What is mapDispatchToProps?

mapStateToProps() is a utility which helps your component get updated state(which is updated by some other components),
mapDispatchToProps() is a utility which will help your component to fire an action event (dispatching action which may cause change of application state)

How to get progress from XMLHttpRequest

For the total uploaded there doesn't seem to be a way to handle that, but there's something similar to what you want for download. Once readyState is 3, you can periodically query responseText to get all the content downloaded so far as a String (this doesn't work in IE), up until all of it is available at which point it will transition to readyState 4. The total bytes downloaded at any given time will be equal to the total bytes in the string stored in responseText.

For a all or nothing approach to the upload question, since you have to pass a string for upload (and it's possible to determine the total bytes of that) the total bytes sent for readyState 0 and 1 will be 0, and the total for readyState 2 will be the total bytes in the string you passed in. The total bytes both sent and received in readyState 3 and 4 will be the sum of the bytes in the original string plus the total bytes in responseText.

How to find first element of array matching a boolean condition in JavaScript?

Since ES6 there is the native find method for arrays; this stops enumerating the array once it finds the first match and returns the value.

const result = someArray.find(isNotNullNorUndefined);

Old answer:

I have to post an answer to stop these filter suggestions :-)

since there are so many functional-style array methods in ECMAScript, perhaps there's something out there already like this?

You can use the some Array method to iterate the array until a condition is met (and then stop). Unfortunately it will only return whether the condition was met once, not by which element (or at what index) it was met. So we have to amend it a little:

function find(arr, test, ctx) {
    var result = null;
    arr.some(function(el, i) {
        return, el, i, arr) ? ((result = el), true) : false;
    return result;
var result = find(someArray, isNotNullNorUndefined);

How to get hostname from IP (Linux)?

Another simple way I found for using in LAN is

ssh [username@ip] uname -n

If you need to login command line will be

sshpass -p "[password]" ssh [username@ip] uname -n

How do I change the font size of a UILabel in Swift?

It's very easy and convenient to change font size from storyboard, and you can instantly see the result of the change.

Actually, it's also very easy to change other font attributes on storyboard too, like style, font family, etc.

enter image description here

Can you remove elements from a std::list while iterating through it?

You have to increment the iterator first (with i++) and then remove the previous element (e.g., by using the returned value from i++). You can change the code to a while loop like so:

std::list<item*>::iterator i = items.begin();
while (i != items.end())
    bool isActive = (*i)->update();
    if (!isActive)
        items.erase(i++);  // alternatively, i = items.erase(i);

Efficient way to return a std::vector in c++

As nice as "return by value" might be, it's the kind of code that can lead one into error. Consider the following program:

    #include <string>
    #include <vector>
    #include <iostream>
    using namespace std;
    static std::vector<std::string> strings;
    std::vector<std::string> vecFunc(void) { return strings; };
    int main(int argc, char * argv[]){
      // set up the vector of strings to hold however
      // many strings the user provides on the command line
      for(int idx=1; (idx<argc); ++idx){

      // now, iterate the strings and print them using the vector function
      // as accessor
      for(std::vector<std::string>::interator idx=vecFunc().begin(); (idx!=vecFunc().end()); ++idx){
         cout << "Addr: " << idx->c_str() << std::endl;
         cout << "Val:  " << *idx << std::endl;
    return 0;
  • Q: What will happen when the above is executed? A: A coredump.
  • Q: Why didn't the compiler catch the mistake? A: Because the program is syntactically, although not semantically, correct.
  • Q: What happens if you modify vecFunc() to return a reference? A: The program runs to completion and produces the expected result.
  • Q: What is the difference? A: The compiler does not have to create and manage anonymous objects. The programmer has instructed the compiler to use exactly one object for the iterator and for endpoint determination, rather than two different objects as the broken example does.

The above erroneous program will indicate no errors even if one uses the GNU g++ reporting options -Wall -Wextra -Weffc++

If you must produce a value, then the following would work in place of calling vecFunc() twice:

   std::vector<std::string> lclvec(vecFunc());
   for(std::vector<std::string>::iterator idx=lclvec.begin(); (idx!=lclvec.end()); ++idx)...

The above also produces no anonymous objects during iteration of the loop, but requires a possible copy operation (which, as some note, might be optimized away under some circumstances. But the reference method guarantees that no copy will be produced. Believing the compiler will perform RVO is no substitute for trying to build the most efficient code you can. If you can moot the need for the compiler to do RVO, you are ahead of the game.

Create File If File Does Not Exist


using FileStream fileStream = File.Open(path, FileMode.Append);
using StreamWriter file = new StreamWriter(fileStream);
// ...

jQuery AJAX single file upload

A. Grab file data from the file field

The first thing to do is bind a function to the change event on your file field and a function for grabbing the file data:

// Variable to store your files
var files;

// Add events
$('input[type=file]').on('change', prepareUpload);

// Grab the files and set them to our variable
function prepareUpload(event)
  files =;

This saves the file data to a file variable for later use.

B. Handle the file upload on submit

When the form is submitted you need to handle the file upload in its own AJAX request. Add the following binding and function:

$('form').on('submit', uploadFiles);

// Catch the form submit and upload the files
function uploadFiles(event)
  event.stopPropagation(); // Stop stuff happening
    event.preventDefault(); // Totally stop stuff happening


// Create a formdata object and add the files
var data = new FormData();
$.each(files, function(key, value)
    data.append(key, value);

    url: 'submit.php?files',
    type: 'POST',
    data: data,
    cache: false,
    dataType: 'json',
    processData: false, // Don't process the files
    contentType: false, // Set content type to false as jQuery will tell the server its a query string request
    success: function(data, textStatus, jqXHR)
        if(typeof data.error === 'undefined')
            // Success so call function to process the form
            submitForm(event, data);
            // Handle errors here
            console.log('ERRORS: ' + data.error);
    error: function(jqXHR, textStatus, errorThrown)
        // Handle errors here
        console.log('ERRORS: ' + textStatus);

What this function does is create a new formData object and appends each file to it. It then passes that data as a request to the server. 2 attributes need to be set to false:

  • processData - Because jQuery will convert the files arrays into strings and the server can't pick it up.
  • contentType - Set this to false because jQuery defaults to application/x-www-form-urlencoded and doesn't send the files. Also setting it to multipart/form-data doesn't seem to work either.

C. Upload the files

Quick and dirty php script to upload the files and pass back some info:

<?php // You need to add server side validation and better error handling here

$data = array();

$error = false;
$files = array();

$uploaddir = './uploads/';
foreach($_FILES as $file)
    if(move_uploaded_file($file['tmp_name'], $uploaddir .basename($file['name'])))
        $files[] = $uploaddir .$file['name'];
        $error = true;
$data = ($error) ? array('error' => 'There was an error uploading your files') : array('files' => $files);
    $data = array('success' => 'Form was submitted', 'formData' => $_POST);

echo json_encode($data);


IMP: Don't use this, write your own.

D. Handle the form submit

The success method of the upload function passes the data sent back from the server to the submit function. You can then pass that to the server as part of your post:

function submitForm(event, data)
  // Create a jQuery object from the form
$form = $(;

// Serialize the form data
var formData = $form.serialize();

// You should sterilise the file names
$.each(data.files, function(key, value)
    formData = formData + '&filenames[]=' + value;

    url: 'submit.php',
    type: 'POST',
    data: formData,
    cache: false,
    dataType: 'json',
    success: function(data, textStatus, jqXHR)
        if(typeof data.error === 'undefined')
            // Success so call function to process the form
            console.log('SUCCESS: ' + data.success);
            // Handle errors here
            console.log('ERRORS: ' + data.error);
    error: function(jqXHR, textStatus, errorThrown)
        // Handle errors here
        console.log('ERRORS: ' + textStatus);
    complete: function()

Final note

This script is an example only, you'll need to handle both server and client side validation and some way to notify users that the file upload is happening. I made a project for it on Github if you want to see it working.

Referenced From

How to control the width of select tag?

USE style="max-width:90%;"

<select name=countries  style="max-width:90%;">
 <option value=af>Afghanistan</option>
 <option value=ax>Åland Islands</option>
 <option value=gs>South Georgia and the South Sandwich Islands</option>


Excel VBA: Copying multiple sheets into new workbook

Try do something like this (the problem was that you trying to use MyBook.Worksheets, but MyBook is not a Workbook object, but string, containing workbook name. I've added new varible Set WB = ActiveWorkbook, so you can use WB.Worksheets instead MyBook.Worksheets):

Sub NewWBandPasteSpecialALLSheets()
   MyBook = ActiveWorkbook.Name ' Get name of this book
   Workbooks.Add ' Open a new workbook
   NewBook = ActiveWorkbook.Name ' Save name of new book

   Workbooks(MyBook).Activate ' Back to original book

   Set WB = ActiveWorkbook

   Dim SH As Worksheet

   For Each SH In WB.Worksheets



       With SH.Range("A1")
        .PasteSpecial (xlPasteColumnWidths)
        .PasteSpecial (xlFormats)
        .PasteSpecial (xlValues)

       End With


End Sub

But your code doesn't do what you want: it doesen't copy something to a new WB. So, the code below do it for you:

Sub NewWBandPasteSpecialALLSheets()
   Dim wb As Workbook
   Dim wbNew As Workbook
   Dim sh As Worksheet
   Dim shNew As Worksheet

   Set wb = ThisWorkbook
   Workbooks.Add ' Open a new workbook
   Set wbNew = ActiveWorkbook

   On Error Resume Next

   For Each sh In wb.Worksheets

      'add new sheet into new workbook with the same name
      With wbNew.Worksheets

          Set shNew = Nothing
          Set shNew = .Item(sh.Name)

          If shNew Is Nothing Then
              .Add After:=.Item(.Count)
              .Item(.Count).Name = sh.Name
              Set shNew = .Item(.Count)
          End If
      End With

      With shNew.Range("A1")
          .PasteSpecial (xlPasteColumnWidths)
          .PasteSpecial (xlFormats)
          .PasteSpecial (xlValues)
      End With
End Sub

Form inside a table

If you want a "editable grid" i.e. a table like structure that allows you to make any of the rows a form, use CSS that mimics the TABLE tag's layout: display:table, display:table-row, and display:table-cell.

There is no need to wrap your whole table in a form and no need to create a separate form and table for each apparent row of your table.

Try this instead:

<div class="table">
    <form class="tr" method="post" action="blah.html">
        <span class="td"><input type="text"/></span>
        <span class="td"><input type="text"/></span>
    <div class="tr">
        <span class="td">(cell data)</span>
        <span class="td">(cell data)</span>

The problem with wrapping the whole TABLE in a FORM is that any and all form elements will be sent on submit (maybe that is desired but probably not). This method allows you to define a form for each "row" and send only that row of data on submit.

The problem with wrapping a FORM tag around a TR tag (or TR around a FORM) is that it's invalid HTML. The FORM will still allow submit as usual but at this point the DOM is broken. Note: Try getting the child elements of your FORM or TR with JavaScript, it can lead to unexpected results.

Note that IE7 doesn't support these CSS table styles and IE8 will need a doctype declaration to get it into "standards" mode: (try this one or something equivalent)

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"

Any other browser that supports display:table, display:table-row and display:table-cell should display your css data table the same as it would if you were using the TABLE, TR and TD tags. Most of them do.

Note that you can also mimic THEAD, TBODY, TFOOT by wrapping your row groups in another DIV with display: table-header-group, table-row-group and table-footer-group respectively.

NOTE: The only thing you cannot do with this method is colspan.

Check out this illustration:

Build Error - missing required architecture i386 in file

I just want to let you know that In my case, I was having the same problem, I realized that I had an older Xcode folder called Xcode3.1.3 I just rename it because it was an older version and that did the magic for me.

Filter values only if not null using lambda in Java8

You just need to filter the cars that have a null name:

requiredCars =
                   .filter(c -> c.getName() != null)
                   .filter(c -> c.getName().startsWith("M"));

Vue.js getting an element within a component

you can access the children of a vuejs component with this.$children. if you want to use the query selector on the current component instance then this.$el.querySelector(...)

just doing a simple console.log(this) will show you all the properties of a vue component instance.

additionally if you know the element you want to access in your component, you can add the v-el:uniquename directive to it and access it via this.$els.uniquename

Error: Cannot pull with rebase: You have unstaged changes

When the unstaged change is because git is attempting to fix eol conventions on a file (as is always my case), no amount of stashing or checking-out or resetting will make it go away.

However, if the intent is really to rebase and ignore unstaged changed, then what I do is delete the branch locally then check it out again.

git checkout -f anyotherbranchthanthisone
git branch -D thebranchineedtorebase
git checkout thebranchineedtorebase

Voila! It hasn't failed me yet.

How to line-break from css, without using <br />?

There are several options for defining the handling of white spaces and line breaks. If one can put the content in e.g. a <p> tag it is pretty easy to get whatever one wants.

For preserving line breaks but not white spaces use pre-line (not pre) like in:

 p {
     white-space: pre-line; /* collapse WS, preserve LB */

How are you</p>

If another behavior is wanted choose among one of these (WS=WhiteSpace, LB=LineBreak):

     white-space: normal;   /* collapse WS, wrap as necessary, collapse LB */
     white-space: nowrap;   /* collapse WS, no wrapping,       collapse LB */
     white-space: pre;      /* preserve WS, no wrapping,       preserve LB */
     white-space: pre-wrap; /* preserve WS, wrap as necessary, preserve LB */
     white-space: inherit;  /* all as parent element */

SOURCE: W3 Schools

How to hide elements without having them take space on the page?

Thanks to this question. I wanted the exact opposite, i.e a hidden div should still occupy its space on the browser. So, I used visibility: hidden instead of display: none.

JUnit tests pass in Eclipse but fail in Maven Surefire

Test execution result different from JUnit run and from maven install seems to be symptom for several problems.

Disabling thread reusing test execution did also get rid of the symptom in our case, but the impression that the code was not thread-safe was still strong.

In our case the difference was due to the presence of a bean that modified the test behaviour. Running just the JUnit test would result fine, but running the project install target would result in a failed test case. Since it was the test case under development, it was immediately suspicious.

It resulted that another test case was instantiating a bean through Spring that would survive until the execution of the new test case. The bean presence was modifying the behaviour of some classes and producing the failed result.

The solution in our case was getting rid of the bean, which was not needed in the first place (yet another prize from the copy+paste gun).

I suggest everybody with this symptom to investigate what the root cause is. Disabling thread reuse in test execution might only hide it.

How to declare and add items to an array in Python?

{} represents an empty dictionary, not an array/list. For lists or arrays, you need [].

To initialize an empty list do this:

my_list = []


my_list = list()

To add elements to the list, use append


To extend the list to include the elements from another list use extend

--> [12,1,2,3,4]

To remove an element from a list use remove


Dictionaries represent a collection of key/value pairs also known as an associative array or a map.

To initialize an empty dictionary use {} or dict()

Dictionaries have keys and values

my_dict = {'key':'value', 'another_key' : 0}

To extend a dictionary with the contents of another dictionary you may use the update method

my_dict.update({'third_key' : 1})

To remove a value from a dictionary

del my_dict['key']

How to create custom button in Android using XML Styles

Have you ever tried to create the background shape for any buttons?

Check this out below:

Below is the separated image from your image of a button.

enter image description here

Now, put that in your ImageButton for android:src "source" like so:


Now, just create shape of the ImageButton to have a black shader background.


and the button_shape is the xml file in drawable resource:

    <?xml version="1.0" encoding="UTF-8"?>
        android:radius="7dp" />


    <solid android:color="#505050"/>


Just try to implement it with this. You might need to change the color value as per your requirement.

Let me know if it doesn't work.

Excel VBA - Range.Copy transpose paste

WorksheetFunction Transpose()

Instead of copying, pasting via PasteSpecial, and using the Transpose option you can simply type a formula


or if you prefer VBA:

    Dim v
    v = WorksheetFunction.Transpose(Sheet1.Range("A1:A5"))
    Sheet2.Range("A1").Resize(1, UBound(v)) = v

Note: alternatively you could use late-bound Application.Transpose instead.

MS help reference states that having a current version of Microsoft 365, one can simply input the formula in the top-left-cell of the target range, otherwise the formula must be entered as a legacy array formula via Ctrl+Shift+Enter to confirm it.

Versions Excel vers. 2007+, Mac since 2011, Excel for Microsoft 365

Does Typescript support the ?. operator? (And, what's it called?)

It's finally here!

Here are a few examples:

// properties

// indexing

// check if a function is defined before invoking

But it doesn't work exactly the same as your assumption.

Instead of evaluating


to this little code snippet we are all used to writing

foo ? : null

it actually evaluates to

(foo === null || foo === undefined) ?
    undefined :

which works for all the falsey values like an empty string, 0 or false.

I just don't have an explanation as to why they don't compile it to foo == null

When to use setAttribute vs .attribute= in JavaScript?

methods for setting attributes(for example class) on an element: 1. el.className = string 2. el.setAttribute('class',string) 3. el.attributes.setNamedItem(object) 4. el.setAttributeNode(node)

I have made a simple benchmark test (here)

and it seems that setAttributeNode is about 3 times faster then using setAttribute.

so if performance is an issue - use "setAttributeNode"

SQL Server remove milliseconds from datetime

Use 'Smalldatetime' data type

select convert(smalldatetime, getdate())

will fetch

2015-01-08 15:27:00

Make text wrap in a cell with FPDF?

Text Wrap:

The MultiCell is used for print text with multiple lines. It has the same atributes of Cell except for ln and link.

$pdf->MultiCell( 200, 40, $reportSubtitle, 1);

Line Height:

What multiCell does is to spread the given text into multiple cells, this means that the second parameter defines the height of each line (individual cell) and not the height of all cells (collectively).

MultiCell(float w, float h, string txt [, mixed border [, string align [, boolean fill]]])

You can read the full documentation here.

Pagination using MySQL LIMIT, OFFSET

First off, don't have a separate server script for each page, that is just madness. Most applications implement pagination via use of a pagination parameter in the URL. Something like:

You can access the requested page number via $_GET['page'].

This makes your SQL formulation really easy:

// determine page number from $_GET
$page = 1;
if(!empty($_GET['page'])) {
    $page = filter_input(INPUT_GET, 'page', FILTER_VALIDATE_INT);
    if(false === $page) {
        $page = 1;

// set the number of items to display per page
$items_per_page = 4;

// build query
$offset = ($page - 1) * $items_per_page;
$sql = "SELECT * FROM menuitem LIMIT " . $offset . "," . $items_per_page;

So for example if input here was page=2, with 4 rows per page, your query would be"

SELECT * FROM menuitem LIMIT 4,4

So that is the basic problem of pagination. Now, you have the added requirement that you want to understand the total number of pages (so that you can determine if "NEXT PAGE" should be shown or if you wanted to allow direct access to page X via a link).

In order to do this, you must understand the number of rows in the table.

You can simply do this with a DB call before trying to return your actual limited record set (I say BEFORE since you obviously want to validate that the requested page exists).

This is actually quite simple:

$sql = "SELECT your_primary_key_field FROM menuitem";
$result = mysqli_query($con, $sql);
if(false === $result) {
   throw new Exception('Query failed with: ' . mysqli_error());
} else {
   $row_count = mysqli_num_rows($result);
   // free the result set as you don't need it anymore

$page_count = 0;
if (0 === $row_count) {  
    // maybe show some error since there is nothing in your table
} else {
   // determine page_count
   $page_count = (int)ceil($row_count / $items_per_page);
   // double check that request page is in range
   if($page > $page_count) {
        // error to user, maybe set page to 1
        $page = 1;

// make your LIMIT query here as shown above

// later when outputting page, you can simply work with $page and $page_count to output links
// for example
for ($i = 1; $i <= $page_count; $i++) {
   if ($i === $page) { // this is current page
       echo 'Page ' . $i . '<br>';
   } else { // show link to other page   
       echo '<a href="/menuitem.php?page=' . $i . '">Page ' . $i . '</a><br>';

String to Binary in C#

It sounds like you basically want to take an ASCII string, or more preferably, a byte[] (as you can encode your string to a byte[] using your preferred encoding mode) into a string of ones and zeros? i.e. 101010010010100100100101001010010100101001010010101000010111101101010

This will do that for you...

//Formats a byte[] into a binary string (010010010010100101010)
public string Format(byte[] data)
    //storage for the resulting string
    string result = string.Empty;
    //iterate through the byte[]
    foreach(byte value in data)
        //storage for the individual byte
        string binarybyte = Convert.ToString(value, 2);
        //if the binarybyte is not 8 characters long, its not a proper result
        while(binarybyte.Length < 8)
            //prepend the value with a 0
            binarybyte = "0" + binarybyte;
        //append the binarybyte to the result
        result += binarybyte;
    //return the result
    return result;

Split comma-separated values

Lamba expression aren't included in c# 2.0

maybe you could refert to this post here on SO

Sending Multipart File as POST parameters with RestTemplate requests

If you have to send a multipart file that is composed, among other things, by an Object that needs to be converted with a specific HttpMessageConverter and you get the "no suitable HttpMessageConverter" error no matter what you try, you may want to try with this:

RestTemplate restTemplate = new RestTemplate();
FormHttpMessageConverter converter = new FormHttpMessageConverter();

converter.addPartConverter(new TheRequiredHttpMessageConverter());
//for example, in my case it was "new MappingJackson2HttpMessageConverter()"


This solved the problem for me with a custom Object that, together with a file (instanceof FileSystemResource, in my case), was part of the multipart file I needed to send. I tried with TrueGuidance's solution (and many others found around the web) to no avail, then I looked at FormHttpMessageConverter's source code and tried this.

SSL Connection / Connection Reset with IISExpress

My problem was caused by Fiddler. When Fiddler crashes it occasionally messes with your proxy settings. Simply launching Fiddler seemed to fix everything (perhaps it repairs itself somehow).

How to find difference between two columns data?

IF the table is alias t

SELECT t.Present , t.previous, t.previous- t.Present AS Difference
FROM   temp1 as t

Where does PHP's error log reside in XAMPP?

Look in your configuration file and search for the error_log setting. Or use phpinfo() to find this setting.

How to make a GridLayout fit screen size

If you use fragments you can prepare XML layout and than stratch critical elements programmatically

int thirdScreenWidth = (int)(screenWidth *0.33);

View view = inflater.inflate(R.layout.fragment_second, null);
View _container = view.findViewById(;
_container.getLayoutParams().width = thirdScreenWidth * 2;

_container = view.findViewById(;
_container.getLayoutParams().width = screenWidth - thirdScreenWidth * 2;

_container = view.findViewById(;
_container.getLayoutParams().width = screenWidth - thirdScreenWidth * 2;

This layout for 3 equal columns. First element takes 2x2 Result in the picture enter image description here

Using the rJava package on Win7 64 bit with R

Sorry for necro. I have too run into the same issue and found out that rJava expects JAVA_HOME to point to JRE. If you have JDK installed, most probably your JAVA_HOME points to JDK. My quick solution:

Sys.setenv(JAVA_HOME=paste(Sys.getenv("JAVA_HOME"), "jre", sep="\\"))

Any way to select without causing locking in MySQL?

Here is an alternative programming solution that may work for others who use MyISAM IF (important) you don't care if an update has happened during the middle of the queries. As we know MyISAM can cause table level locks, especially if you have an update pending which will get locked, and then other select queries behind this update get locked too.

So this method won't prevent a lock, but it will make a lot of tiny locks, so as not to hang a website for example which needs a response within a very short frame of time.

The idea here is we grab a range based on an index which is quick, then we do our match from that query only, so it's in smaller batches. Then we move down the list onto the next range and check them for our match.

Example is in Perl with a bit of pseudo code, and traverses high to low.

# object_id must be an index so it's fast
# First get the range of object_id, as it may not start from 0 to reduce empty queries later on.

my ( $first_id, $last_id ) = $db->db_query_array(
  sql => q{ SELECT MIN(object_id), MAX(object_id) FROM mytable }

my $keep_running = 1;
my $step_size    = 1000;
my $next_id      = $last_id;

while( $keep_running ) {

    my $sql = q{ 
SELECT object_id, created, status FROM 
    ( SELECT object_id, created, status FROM mytable AS is1 WHERE is1.object_id <= ? ORDER BY is1.object_id DESC LIMIT ? ) AS is2
WHERE status='live' ORDER BY object_id DESC 

    my $sth = $db->db_query( sql => $sql, args => [ $step_size, $next_id ] );

    while( my ($object_id, $created, $status ) = $sth->fetchrow_array() ) {

        $last_id = $object_id;
        ## do your stuff


    if( !$last_id ) {
        $next_id -= $step_size; # There weren't any matched in the range we grabbed
    } else {
        $next_id = $last_id - 1; # There were some, so we'll start from that.

    $keep_running = 0 if $next_id < 1 || $next_id < $first_id;

How to convert a unix timestamp (seconds since epoch) to Ruby DateTime?

This tells you the date of the number of seconds in future from the moment you execute the code.

time = + 1000000000 #date in 1 billion seconds


according to the current time I am answering the question it prints 047-05-14 05:16:16 +0000 (1 billion seconds in future)

or if you want to count billion seconds from a particular time, it's in format Time.mktime(year, month,date,hours,minutes)

time = Time.mktime(1987,8,18,6,45) + 1000000000

puts("I would be 1 Billion seconds old on: "+time)

How to escape double quotes in JSON

Try this:

"maingame": {
  "day1": {
    "text1": "Tag 1",
     "text2": "Heute startet unsere Rundreise \" Example text\". Jeden Tag wird ein neues Reiseziel angesteuert bis wir.</strong> "

(just one backslash (\) in front of quotes).

What is the standard naming convention for html/css ids and classes?


There is no one true answer. You can pick one of the many out there, or create your own standards based on what makes sense, depending upon who you're working with. And it is 100% dependent upon the platform.

Original Post

Just one more alternative standard to consider:

<div id="id_name" class="class-name"></div>

And in your script:

var variableName = $("#id_name .class-name");

This just uses a camelCase, under_score, and hyphen-ation respectively for variables, ids, and classes. I've read about this standard on a couple of different websites. Although a little redundant in css/jquery selectors, redundancies make it easier to catch errors. eg: If you see .unknown_name or #unknownName in your CSS file, you know you need to figure out what that's actually referring to.


(Hyphens are called 'kebab-case', underscores are called 'snake_case', and then you have 'TitleCase', 'pascalCase')

I personally dislike hyphens. I originally posted this as one alternative (because the rules are simple). However, Hyphens make selection shortcuts very difficult (double click, ctrl/option + left/right, and ctrl/cmd+D in vsCode. Also, class names and file names are the only place where hyphens work, because they're almost always in quotes or in css, etc. But the shortcut thing still applies.

In addition to variables, class names, and ids, you also want to look at file name conventions. And Git Branches.

My office's coding group actually had a meeting a month or two ago to discuss how we were going to name things. For git branches, we couldn't decide between 321-the_issue_description or 321_the-issue-description. (I wanted 321_theIssueDescription, but my coworkers didn't like that.)

An Example, to demonstrate working with other peoples' standards...

Vue.js does have a standard. Actually they have two alternate standards for several of their items. I dislike both of their versions for filenames. They recommend either "/path/kebab-case.vue" or "/path/TitleCase.Vue". The former is harder to rename, unless you're specifically trying to rename part of it. The latter is not good for cross-platform compatibility. I would prefer "/path/snake_case.vue". However, when working with other people or existing projects, it's important to follow whatever standard was already laid out. Therefore I go with kebab-case for filenames in Vue, even though I'll totally complain about it. Because not following that means changing a lot of files that vue-cli sets up.

Upgrading PHP on CentOS 6.5 (Final)

Steps for upgrading to PHP7 on CentOS 6 system. Taken from install-php-7-in-centos-6

To install latest PHP 7, you need to add EPEL and Remi repository to your CentOS 6 system

yum install
yum install

Now install yum-utils, a group of useful tools that enhance yum’s default package management features

yum install yum-utils

In this step, you need to enable Remi repository using yum-config-manager utility, as the default repository for installing PHP.

yum-config-manager --enable remi-php70

If you want to install PHP 7.1 or PHP 7.2 on CentOS 6, just enable it as shown.

yum-config-manager --enable remi-php71 
yum-config-manager --enable remi-php72

Then finally install PHP 7 on CentOS 6 with all necessary PHP modules using the following command.

yum install php php-mcrypt php-cli php-gd php-curl php-mysql php-ldap php-zip php-fileinfo

Double check the installed version of PHP on your system as follows.

php -V 

How do I get NuGet to install/update all the packages in the packages.config?

At VS2012 V11, if I use "-Reinstall" at the end of the line it doesn't work.

So I simply used:

Update-Package -ProjectName 'NAME_OF_THE_PROJECT'

In Unix, how do you remove everything in the current directory and below it?

Practice safe computing. Simply go up one level in the hierarchy and don't use a wildcard expression:

cd ..; rm -rf -- <dir-to-remove>

The two dashes -- tell rm that <dir-to-remove> is not a command-line option, even when it begins with a dash.

Getting a list item by index

You can use the ElementAt extension method on the list.

For example:

// Get the first item from the list

using System.Linq;

var myList = new List<string>{ "Yes", "No", "Maybe"};
var firstItem = myList.ElementAt(0);

// Do something with firstItem

How to get the Touch position in android?

    public boolean onTouch(View v, MotionEvent event) {
       float x = event.getX();
       float y = event.getY();
       return true;

Dart: mapping a list (

I try this same method, but with a different list with more values in the function map. My problem was to forget a return statement. This is very important :)

 bottom: new TabBar(
      controller: _controller,
      isScrollable: true,
      tabs: { return Tab(text: title)}).toList()

Getting Data from Android Play Store

There's an unofficial open-source API for the Android Market you may try to use to get the information you need. Hope this helps.

Set margins in a LinearLayout programmatically

Try this

 LayoutParams params = new LayoutParams(
    params.setMargins(left, top, right, bottom);

Get path of executable

char exePath[512];
CString strexePath;
strexePath = strexePath.Mid(0,strexePath.ReverseFind('\\'));

Change EditText hint color when using TextInputLayout

A lot answers but need only a line for this:



How to implement a Map with multiple keys?

I'm still going suggest the 2 map solution, but with a tweest

Map<K2, K1> m2;
Map<K1, V>  m1;

This scheme lets you have an arbitrary number of key "aliases".

It also lets you update the value through any key without the maps getting out of sync.

How to test if a double is an integer

Or you could use the modulo operator:

(d % 1) == 0

c++ array assignment of multiple values

There is a difference between initialization and assignment. What you want to do is not initialization, but assignment. But such assignment to array is not possible in C++.

Here is what you can do:

#include <algorithm>

int array [] = {1,3,34,5,6};
int newarr [] = {34,2,4,5,6};
std::copy(newarr, newarr + 5, array);

However, in C++0x, you can do this:

std::vector<int> array = {1,3,34,5,6};
array = {34,2,4,5,6};

Of course, if you choose to use std::vector instead of raw array.

Node.js check if file exists

After a bit of experimentation, I found the following example using fs.stat to be a good way to asynchronously check whether a file exists. It also checks that your "file" is "really-is-a-file" (and not a directory).

This method uses Promises, assuming that you are working with an asynchronous codebase:

const fileExists = path => {
  return new Promise((resolve, reject) => {
    try {
      fs.stat(path, (error, file) => {
        if (!error && file.isFile()) {
          return resolve(true);

        if (error && error.code === 'ENOENT') {
          return resolve(false);
    } catch (err) {

If the file does not exist, the promise still resolves, albeit false. If the file does exist, and it is a directory, then is resolves true. Any errors attempting to read the file will reject the promise the error itself.

How can I calculate divide and modulo for integers in C#?

There is also Math.DivRem

quotient = Math.DivRem(dividend, divisor, out remainder);

How to run JUnit tests with Gradle?

How do I add a junit 4 dependency correctly?

Assuming you're resolving against a standard Maven (or equivalent) repo:

dependencies {
    testCompile "junit:junit:4.11"  // Or whatever version

Run those tests in the folders of tests/model?

You define your test source set the same way:

sourceSets {

    test {
        java {
            srcDirs = ["test/model"]  // Note @Peter's comment below

Then invoke the tests as:

./gradlew test

EDIT: If you are using JUnit 5 instead, there are more steps to complete, you should follow this tutorial.

Excel - extracting data based on another list

Have you tried Advanced Filter? Using your short list as the 'Criteria' and long list as the 'List Range'. Use the options: 'Filter in Place' and 'Unique Values'.

You should be presented with the list of unique values that only appear in your short list.

Alternatively, you can paste your Unique list to another location (on the same sheet), if you prefer. Choose the option 'Copy to another Location' and in the 'Copy to' box enter the cell reference (say F1) where you want the Unique list.

Note: this will work with the two columns (name/ID) too, if you select the two columns as both 'Criteria' and 'List Range'.

Difference between <span> and <div> with text-align:center;?

Span is considered an in-line element. As such is basically constrains itself to the content within it. It more or less is transparent.

Think of it having the behavior of the 'b' tag.

It can be performed like <span style='font-weight: bold;'>bold text</span>

div is a block element.

Abstract Class:-Real Time Example

The best example of an abstract class is GenericServlet. GenericServlet is the parent class of HttpServlet. It is an abstract class.

When inheriting 'GenericServlet' in a custom servlet class, the service() method must be overridden.

WebAPI to Return XML

Here's another way to be compatible with an IHttpActionResult return type. In this case I am asking it to use the XML Serializer(optional) instead of Data Contract serializer, I'm using return ResponseMessage( so that I get a return compatible with IHttpActionResult:

return ResponseMessage(new HttpResponseMessage(HttpStatusCode.OK)
           Content = new ObjectContent<SomeType>(objectToSerialize, 
              new System.Net.Http.Formatting.XmlMediaTypeFormatter { 
                  UseXmlSerializer = true 

HTML.HiddenFor value set

You shouldn't need to set the value in the attributes parameter. MVC should automatically bind it for you.

@Html.HiddenFor(model => model.title, new { id= "natureOfVisitField" })

Check file extension in upload form in PHP

Checking the file extension is not considered best practice. The preferred method of accomplishing this task is by checking the files MIME type.

From PHP:

    $finfo = finfo_open(FILEINFO_MIME_TYPE); // Return MIME type
    foreach (glob("*") as $filename) {
        echo finfo_file($finfo, $filename) . "\n";

The above example will output something similar to which you should be checking.


Although MIME types can also be tricked (edit the first few bytes of a file and modify the magic numbers), it's harder than editing a filename. So you can never be 100% sure what that file type actually is, and care should be taken about handling files uploaded/emailed by your users.

How to handle floats and decimal separators with html5 input type number

Use valueAsNumber instead of .val().

input . valueAsNumber [ = value ]

Returns a number representing the form control's value, if applicable; otherwise, returns null.
Can be set, to change the value.
Throws an INVALID_STATE_ERR exception if the control is neither date- or time-based nor numeric.

What is the javascript filename naming convention?

I'm not aware of any particular convention for javascript files as they aren't really unique on the web versus css files or html files or any other type of file like that. There are some "safe" things you can do that make it less likely you will accidentally run into a cross platform issue:

  1. Use all lowercase filenames. There are some operating systems that are not case sensitive for filenames and using all lowercase prevents inadvertently using two files that differ only in case that might not work on some operating systems.
  2. Don't use spaces in the filename. While this technically can be made to work there are lots of reasons why spaces in filenames can lead to problems.
  3. A hyphen is OK for a word separator. If you want to use some sort of separator for multiple words instead of a space or camelcase as in various-scripts.js, a hyphen is a safe and useful and commonly used separator.
  4. Think about using version numbers in your filenames. When you want to upgrade your scripts, plan for the effects of browser or CDN caching. The simplest way to use long term caching (for speed and efficiency), but immediate and safe upgrades when you upgrade a JS file is to include a version number in the deployed filename or path (like jQuery does with jquery-1.6.2.js) and then you bump/change that version number whenever you upgrade/change the file. This will guarantee that no page that requests the newer version is ever served the older version from a cache.

SQL permissions for roles

Unless the role was made dbo, db_owner or db_datawriter, it won't have permission to edit any data. If you want to grant full edit permissions to a single table, do this:

GRANT ALL ON table1 TO doctor 

Users in that role will have no permissions whatsoever to other tables (not even read).

Warning about `$HTTP_RAW_POST_DATA` being deprecated

I just got the solution to this problem from a friend. he said: Add ob_start(); under your session code. You can add exit(); under the header. I tried it and it worked. Hope this helps

This is for those on a rented Hosting sever who do not have access to php.init file.

Android - Package Name convention

The package name is used for unique identification for your application.
Android uses the package name to determine if the application has been installed or not.
The general naming is:



What causes java.lang.IncompatibleClassChangeError?

My answer, I believe, will be Intellij specific.

I had rebuilt clean, even going as far as to manually delete the "out" and "target" dirs. Intellij has a "invalidate caches and restart", which sometimes clears odd errors. This time it didn't work. The dependency versions all looked correct in the project settings->modules menu.

The final answer was to manually delete my problem dependency from my local maven repo. An old version of bouncycastle was the culprit(I knew I had just changed versions and that would be the problem) and although the old version showed up no where in what was being built, it solved my problem. I was using intellij version 14 and then upgraded to 15 during this process.

How to find out "The most popular repositories" on Github?

Ranking by stars or forks is not working. Each promoted or created by a famous company repository is popular at the beginning. Also it is possible to have a number of them which are in trend right now (publications, marketing, events). It doesn't mean that those repositories are useful/popular.

The project (repo at github) analyses GH Archive data in order to highlight the most interesting repositories and exclude others. Just compare the results with mentioned resources.

Regex to match only uppercase "words" with some exceptions

Don't do things like [A-Z] or [0-9]. Do \p{Lu} and \d instead. Of course, this is valid for perl based regex flavours. This includes java.

I would suggest that you don't make some huge regex. First split the text in sentences. then tokenize it (split into words). Use a regex to check each token/word. Skip the first token from sentence. Check if all tokens are uppercase beforehand and skip the whole sentence if so, or alter the regex in this case.

Spring Test & Security: How to mock authentication?

Add in pom.xml:


and use for authorization request. See the sample usage at (


4.0.0.RC2 works for spring-security 3.x. For spring-security 4 spring-security-test become part of spring-security (, version is the same).

Setting Up is changed:

public void setup() {
    mvc = MockMvcBuilders

Sample for basic-authentication:

Remove a JSON attribute

The selected answer would work for as long as you know the key itself that you want to delete but if it should be truly dynamic you would need to use the [] notation instead of the dot notation.

For example:

var keyToDelete = "key1";
var myObj = {"test": {"key1": "value", "key2": "value"}}

//that will not work.
delete myObj.test.keyToDelete 

instead you would need to use:

delete myObj.test[keyToDelete];

Substitute the dot notation with [] notation for those values that you want evaluated before being deleted.

Why is nginx responding to any domain name?

You should have a default server for catch-all, you can return 404 or better to not respond at all (will save some bandwidth) by returning 444 which is nginx specific HTTP response that simply close the connection and return nothing

server {
    listen       80  default_server;
    server_name  _; # some invalid name that won't match anything
    return       444;

Warning: Null value is eliminated by an aggregate or other SET operation in Aqua Data Studio

If any Null value exists inside aggregate function you will face this issue. Instead of below code

 SELECT Count(closed)
  FROM   ticket
  WHERE  assigned_to = c.user_id
  AND closed IS NULL

use like

SELECT Count(ISNULL(closed, 0))
  FROM   ticket
  WHERE  assigned_to = c.user_id
  AND closed IS NULL

Visual Studio Code open tab in new window

When I want to split the screens I usually do one of the following:

  1. open new window with: Ctrl+Shift+N
    and after that I drag the current file I want to the new window.
  2. on the File explorer - I hit Ctrl+Enter on the file I want - and then this file and the other file open together in the same screen but in split mode, so you can see the two files together. If the screen is wide enough this is not a bad solution at all that you can get used to.

How to check for an undefined or null variable in JavaScript?

I think the most efficient way to test for "value is null or undefined" is

if ( some_variable == null ){
  // some_variable is either null or undefined

So these two lines are equivalent:

if ( typeof(some_variable) !== "undefined" && some_variable !== null ) {}
if ( some_variable != null ) {}

Note 1

As mentioned in the question, the short variant requires that some_variable has been declared, otherwise a ReferenceError will be thrown. However in many use cases you can assume that this is safe:

check for optional arguments:

    if( foo == null ) {...}

check for properties on an existing object

if( == null) {...}

On the other hand typeof can deal with undeclared global variables (simply returns undefined). Yet these cases should be reduced to a minimum for good reasons, as Alsciende explained.

Note 2

This - even shorter - variant is not equivalent:

if ( !some_variable ) {
  // some_variable is either null, undefined, 0, NaN, false, or an empty string


if ( some_variable ) {
  // we don't get here if some_variable is null, undefined, 0, NaN, false, or ""

Note 3

In general it is recommended to use === instead of ==. The proposed solution is an exception to this rule. The JSHint syntax checker even provides the eqnull option for this reason.

From the jQuery style guide:

Strict equality checks (===) should be used in favor of ==. The only exception is when checking for undefined and null by way of null.

// Check for both undefined and null values, for some important reason. 
undefOrNull == null;

Copy values from one column to another in the same table

Short answer for the code in question is:

UPDATE `table` SET test=number

Here table is the table name and it's surrounded by grave accent (aka back-ticks `) as this is MySQL convention to escape keywords (and TABLE is a keyword in that case).

BEWARE, that this is pretty dangerous query which will wipe everything in column test in every row of your table replacing it by the number (regardless of it's value)

It is more common to use WHERE clause to limit your query to only specific set of rows:

UPDATE `products` SET `in_stock` = true WHERE `supplier_id` = 10

Download JSON object as a file from browser

Found an answer.

var obj = {a: 123, b: "4 5 6"};
var data = "text/json;charset=utf-8," + encodeURIComponent(JSON.stringify(obj));

$('<a href="data:' + data + '" download="data.json">download JSON</a>').appendTo('#container');

seems to work fine for me.

** All credit goes to @cowboy-ben-alman, who is the author of the code above **

In OS X Lion, LANG is not set to UTF-8, how to fix it?

I had this issue with MacOS High Sierria.

Screenshot 1

You can set up locale as well as language to UTF-8 format using below command :

export LC_ALL=en_US.UTF-8
export LANG=en_US.UTF-8

Screenshot 2

Now in order to check whether locale environment is updated use below command :


Screenshot 3

Prevent overwriting a file using cmd if exist

I noticed some issues with this that might be useful for someone just starting, or a somewhat inexperienced user, to know. First...

CD /D "C:\Documents and Settings\%username%\Start Menu\Programs\"

two things one is that a /D after the CD may prove to be useful in making sure the directory is changed but it's not really necessary, second, if you are going to pass this from user to user you have to add, instead of your name, the code %username%, this makes the code usable on any computer, as long as they have your setup.exe file in the same location as you do on your computer. of course making sure of that is more difficult. also...

start \\filer\repo\lab\"software"\"myapp"\setup.exe

the start code here, can be set up like that, but the correct syntax is

start "\\filter\repo\lab\software\myapp\" setup.exe

This will run: setup.exe, located in: \filter\repo\lab...etc.\

Find if variable is divisible by 2

You can do it in a better way (up to 50 % faster than modulo operator):

odd: x & 1 even: !(x & 1)

Reference: High Performance JavaScript, 8. ->Bitwise Operators

Set focus and cursor to end of text input field / string w. Jquery

You can do this using Input.setSelectionRange, part of the Range API for interacting with text selections and the text cursor:

var searchInput = $('#Search');

// Multiply by 2 to ensure the cursor always ends up at the end;
// Opera sometimes sees a carriage return as 2 characters.
var strLength = searchInput.val().length * 2;

searchInput[0].setSelectionRange(strLength, strLength);

Demo: Fiddle

How do I make Java register a string input with spaces?

Instead of

Scanner in = new Scanner(;
String question;
question =;

Type in

Scanner in = new Scanner(;
String question;
question = in.nextLine();

This should be able to take spaces as input.

How to create strings containing double quotes in Excel formulas?

Three double quotes: " " " x " " " = "x" Excel will auto change to one double quote. e.g.:

=CONCATENATE("""x"""," hi")  

= "x" hi

Invariant Violation: Could not find "store" in either the context or props of "Connect(SportsDatabase)"

For me it was import issue, hope it helps. default import by WebStorm was wrong.


import connect from "react-redux/lib/connect/connect";


import {connect} from "react-redux";

How to get numeric position of alphabets in java?

This depends on the alphabet but for the english one, try this:

String input = "abc".toLowerCase(); //note the to lower case in order to treat a and A the same way
for( int i = 0; i < input.length(); ++i) {
   int position = input.charAt(i) - 'a' + 1;

How to add a column in TSQL after a specific column?

If you are using the GUI to do this you must deselect the following option allowing the table to be dropped,

enter image description here

Creating stored procedure with declare and set variables

I assume you want to pass the Order ID in. So:

CREATE PROCEDURE [dbo].[Procedure_Name]
    @OrderID INT
) AS
    Declare @OrderItemID AS INT
    DECLARE @AppointmentID AS INT
    DECLARE @PurchaseOrderID AS INT
    DECLARE @PurchaseOrderItemID AS INT
    DECLARE @SalesOrderID AS INT
    DECLARE @SalesOrderItemID AS INT

    SET @OrderItemID = (SELECT OrderItemID FROM [OrderItem] WHERE OrderID = @OrderID)
    SET @AppointmentID = (SELECT AppoinmentID FROM [Appointment] WHERE OrderID = @OrderID)
    SET @PurchaseOrderID = (SELECT PurchaseOrderID FROM [PurchaseOrder] WHERE OrderID = @OrderID)

Javascript - remove an array item by value

You can use lodash.js


In your case :- _.pull(id_tag,90);

Unable to install gem - Failed to build gem native extension - cannot load such file -- mkmf (LoadError)

Just finished a 2 hour wild goose chase trying to solve this. None of the posted answers worked for me. Im on a Mac (Mojave Version 10.14.6, Xcode Version 11.3).

It turns out the ruby file headers were missing so i had to run open /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg

That didnt work for me at first because the version of CommandLineTools i had installed did not have the "Packages" folder. So i uninstalled and reinstalled like this:

rm -rf /Library/Developer/CommandLineTools

xcode-select --install

Then i ran the previous command again:

open /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg

After install the error was fixed!

How to Detect cause of 503 Service Temporarily Unavailable error and handle it?

There is of course some apache log files. Search in your apache configuration files for 'Log' keyword, you'll certainly find plenty of them. Depending on your OS and installation places may vary (in a Typical Linux server it would be /var/log/apache2/[access|error].log).

Having a 503 error in Apache usually means the proxied page/service is not available. I assume you're using tomcat and that means tomcat is either not responding to apache (timeout?) or not even available (down? crashed?). So chances are that it's a configuration error in the way to connect apache and tomcat or an application inside tomcat that is not even sending a response for apache.

Sometimes, in production servers, it can as well be that you get too much traffic for the tomcat server, apache handle more request than the proxyied service (tomcat) can accept so the backend became unavailable.

C# Linq Group By on multiple columns

Given a list:

var list = new List<Child>()
    new Child()
        {School = "School1", FavoriteColor = "blue", Friend = "Bob", Name = "John"},
    new Child()
        {School = "School2", FavoriteColor = "blue", Friend = "Bob", Name = "Pete"},
    new Child()
        {School = "School1", FavoriteColor = "blue", Friend = "Bob", Name = "Fred"},
    new Child()
        {School = "School2", FavoriteColor = "blue", Friend = "Fred", Name = "Bob"},

The query would look like:

var newList = list
    .GroupBy(x => new {x.School, x.Friend, x.FavoriteColor})
    .Select(y => new ConsolidatedChild()
            FavoriteColor = y.Key.FavoriteColor,
            Friend = y.Key.Friend,
            School = y.Key.School,
            Children = y.ToList()

Test code:

foreach(var item in newList)
    Console.WriteLine("School: {0} FavouriteColor: {1} Friend: {2}", item.School,item.FavoriteColor,item.Friend);
    foreach(var child in item.Children)
        Console.WriteLine("\t Name: {0}", child.Name);


School: School1 FavouriteColor: blue Friend: Bob
    Name: John
    Name: Fred
School: School2 FavouriteColor: blue Friend: Bob
    Name: Pete
School: School2 FavouriteColor: blue Friend: Fred
    Name: Bob

Table 'performance_schema.session_variables' doesn't exist

For my system the problem ended up being that I still had Mysql 5.6 installed and so the mysql_upgrade.exe from that installation was being called instead of the one for 5.7. Navigate to C:\Program Files\MySQL\MySQL Server 5.7\bin and run .\mysql_upgrade.exe -u root

How do I add a library path in cmake?

You had better use find_library command instead of link_directories. Concretely speaking there are two ways:

  1. designate the path within the command

    find_library(NAMES gtest PATHS path1 path2 ... pathN)

  2. set the variable CMAKE_LIBRARY_PATH

    set(CMAKE_LIBRARY_PATH path1 path2)
    find_library(NAMES gtest)

the reason is as flowings:

Note This command is rarely necessary and should be avoided where there are other choices. Prefer to pass full absolute paths to libraries where possible, since this ensures the correct library will always be linked. The find_library() command provides the full path, which can generally be used directly in calls to target_link_libraries(). Situations where a library search path may be needed include: Project generators like Xcode where the user can switch target architecture at build time, but a full path to a library cannot be used because it only provides one architecture (i.e. it is not a universal binary).

Libraries may themselves have other private library dependencies that expect to be found via RPATH mechanisms, but some linkers are not able to fully decode those paths (e.g. due to the presence of things like $ORIGIN).

If a library search path must be provided, prefer to localize the effect where possible by using the target_link_directories() command rather than link_directories(). The target-specific command can also control how the search directories propagate to other dependent targets.

how to get javaScript event source element?

You can pass this when you call the function

<button onclick="doSomething('param',this)" id="id_button">action</button>

    function doSomething(param,me){

    var source = me

Node Express sending image files as API response

There is an api in Express.


app.get('/report/:chart_id/:user_id', function (req, res) {
    // res.sendFile(filepath);

How to select records without duplicate on just one field in SQL?

DISTINCT is the keyword
For me your query is correct

Just try to do this first

SELECT DISTINCT title,id FROM tbl_countries

Later on you can try with order by.

Jenkins vs Travis-CI. Which one would you use for a Open Source project?

Travis-ci and Jenkins, while both are tools for continuous integration are very different.

Travis is a hosted service (free for open source) while you have to host, install and configure Jenkins.

Travis does not have jobs as in Jenkins. The commands to run to test the code are taken from a file named .travis.yml which sits along your project code. This makes it easy to have different test code per branch since each branch can have its own version of the .travis.yml file.

You can have a similar feature with Jenkins if you use one of the following plugins:

  • Travis YML Plugin - warning: does not seem to be popular, probably not feature complete in comparison to the real Travis.
  • Jervis - a modification of Jenkins to make it read create jobs from a .jervis.yml file found at the root of project code. If .jervis.yml does not exist, it will fall back to using .travis.yml file instead.

There are other hosted services you might also consider for continuous integration (non exhaustive list):

How to choose ?

You might want to stay with Jenkins because you are familiar with it or don't want to depend on 3rd party for your continuous integration system. Else I would drop Jenkins and go with one of the free hosted CI services as they save you a lot of trouble (host, install, configure, prepare jobs)

Depending on where your code repository is hosted I would make the following choices:

  • in-house ? Jenkins or gitlab-ci
  • ? Travis-CI

To setup Travis-CI on a github project, all you have to do is:

  • add a .travis.yml file at the root of your project
  • create an account at and activate your project

The features you get are:

  • Travis will run your tests for every push made on your repo
  • Travis will run your tests on every pull request contributors will make

How to set up a Web API controller for multipart/form-data

5 years later on and .NET Core 3.1 allows you to do specify the media type like this:

public IActionResult UploadLogo()
    return Ok();

Editable 'Select' element

Based on the other answers, here is a first draft for usage with knockout:


      <div data-bind="editableSelect: {options: optionsObservable, value: nameObservable}"></div>

Knockout data binding

    init: function(hostElement, valueAccessor) {

      var optionsObservable = getOptionsObservable();
      var valueObservable = getValueObservable();

      var $editableSelect = $(hostElement);

      var editableSelect = $editableSelect[0];

      var viewModel = new editableSelectViewModel(optionsObservable, valueObservable);
      ko.applyBindingsToNode(editableSelect, { compose: viewModel });

      //tell knockout to not apply bindings twice
      return { controlsDescendantBindings: true };

      function getOptionsObservable() {
        var accessor = valueAccessor();
        return getAttribute(accessor, 'options');

      function getValueObservable() {
        var accessor = valueAccessor();
        return getAttribute(accessor, 'value');


  data-bind="options: options, event:{ focus: resetComboBoxValue, change: setTextFieldValue} "
  data-bind="value: value, , event:{ focus: textFieldGotFocus, focusout: textFieldLostFocus}"


], function(
) {

  var viewModel = function(optionsObservable, valueObservable) {

    var self = this;
    self.options = optionsObservable();
    self.value = valueObservable;
    self.resetComboBoxValue = resetComboBoxValue;
    self.setTextFieldValue = setTextFieldValue;
    self.textFieldGotFocus = textFieldGotFocus;
    self.textFieldLostFocus = textFieldLostFocus;

    function resetComboBoxValue() {

    function setTextFieldValue() {
      var selection = $('#comboBox').val();

    function textFieldGotFocus() {


    function textFieldLostFocus() {


  return viewModel;


.select-editable {

  display: block;
  width: 100%;
  height: 31px;
  padding: 6px 12px;
  font-size: 12px;
  line-height: 1.42857143;
  color: #555555;
  background-color: #ffffff;
  background-image: none;
  border: 1px solid #cccccc;
  border-radius: 0px;
  -webkit-box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.075);
  box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.075);
  -webkit-transition: border-color ease-in-out .15s, -webkit-box-shadow ease-in-out .15s;
  -o-transition: border-color ease-in-out .15s, box-shadow ease-in-out .15s;
  transition: border-color ease-in-out .15s, box-shadow ease-in-out .15s;padding: 0;

.select-editable select {
  padding-left: 10px;
  height: 29px;

.select-editable input {
  position: relative;
  top: -27px;
  margin-left: 10px;
  height: 25px;

.select-editable select:focus {
  border: 1px solid #66afe9;
  -webkit-box-shadow: inset 0 1px 1px rgba(0,0,0,.075), 0 0 8px rgba(102, 175, 233, 0.6);
  box-shadow: inset 0 1px 1px rgba(0,0,0,.075), 0 0 8px rgba(102, 175, 233, 0.6);

.select-editable input:focus {

.select-editable-input-focus {
  border: 1px solid #66afe9 !important;
  -webkit-box-shadow: inset 0 1px 1px rgba(0,0,0,.075), 0 0 8px rgba(102, 175, 233, 0.6);
  box-shadow: inset 0 1px 1px rgba(0,0,0,.075), 0 0 8px rgba(102, 175, 233, 0.6);

Equivalent function for DATEADD() in Oracle

Not my answer :

I wasn't too happy with the answers above and some additional searching yielded this :

SELECT SYSDATE AS current_date,

       SYSDATE + 1 AS plus_1_day,

       SYSDATE + 1/24 AS plus_1_hours,

       SYSDATE + 1/24/60 AS plus_1_minutes,

       SYSDATE + 1/24/60/60 AS plus_1_seconds

FROM   dual;

which I found very helpful. From

Why are exclamation marks used in Ruby methods?


I like to think of this as an explosive change that destroys all that has gone before it. Bang or exclamation mark means that you are making a permanent saved change in your code.

If you use for example Ruby's method for global substitutiongsub!the substitution you make is permanent.

Another way you can imagine it, is opening a text file and doing find and replace, followed by saving. ! does the same in your code.

Another useful reminder if you come from the bash world is sed -i has this similar effect of making permanent saved change.


Just a little tip:

I prefer to use the variant RLIKE (exactly the same command as REGEXP) as it sounds more like natural language, and is shorter; well, just 1 char.

The "R" prefix is for Reg. Exp., of course.

Using CSS to insert text

The answer using jQuery that everyone seems to like has a major flaw, which is it is not scalable (at least as it is written). I think Martin Hansen has the right idea, which is to use HTML5 data-* attributes. And you can even use the apostrophe correctly:


<div class="task" data-task-owner="Joe">mop kitchen</div>
<div class="task" data-task-owner="Charles" data-apos="1">vacuum hallway</div>


div.task:before { content: attr(data-task-owner)"'s task - " ; }
div.task[data-apos]:before { content: attr(data-task-owner)"' task - " ; }


Joe's task - mop kitchen
Charles' task - vacuum hallway

How can I properly handle 404 in ASP.NET MVC?

Adding my solution, which is almost identical to Herman Kan's, with a small wrinkle to allow it to work for my project.

Create a custom error controller:

public class Error404Controller : BaseController
    public ActionResult PageNotFound()
        Response.StatusCode = 404;
        return View("404");

Then create a custom controller factory:

public class CustomControllerFactory : DefaultControllerFactory
    protected override IController GetControllerInstance(RequestContext requestContext, Type controllerType)
        return controllerType == null ? new Error404Controller() : base.GetControllerInstance(requestContext, controllerType);

Finally, add an override to the custom error controller:

protected override void HandleUnknownAction(string actionName)
    var errorRoute = new RouteData();
    errorRoute.Values.Add("controller", "Error404");
    errorRoute.Values.Add("action", "PageNotFound");
    new Error404Controller().Execute(new RequestContext(HttpContext, errorRoute));

And that's it. No need for Web.config changes.

A potentially dangerous Request.Form value was detected from the client

There's a different solution to this error if you're using ASP.NET MVC:

C# sample:

[HttpPost, ValidateInput(false)]
public ActionResult Edit(FormCollection collection)
    // ...

Visual Basic sample:

<AcceptVerbs(HttpVerbs.Post), ValidateInput(False)> _
Function Edit(ByVal collection As FormCollection) As ActionResult
End Function

Getting Error 800a0e7a "Provider cannot be found. It may not be properly installed."

install this

install the 32 bit version no matter whether you are 64 bit and enable the 32 bit apps in the application pool

How to print React component on click of a button?

On 6/19/2017 This worked perfect for me.

import React, { Component } from 'react'

class PrintThisComponent extends Component {
  render() {
    return (
        <button onClick={() => window.print()}>PRINT</button>
        <p>Click above button opens print preview with these words on page</p>

export default PrintThisComponent

How to take column-slices of dataframe in pandas

Also, Given a DataFrame


as in your example, if you would like to extract column a and d only (e.i. the 1st and the 4th column), iloc mothod from the pandas dataframe is what you need and could be used very effectively. All you need to know is the index of the columns you would like to extract. For example:

>>> data.iloc[:,[0,3]]

will give you

          a         d
0  0.883283  0.100975
1  0.614313  0.221731
2  0.438963  0.224361
3  0.466078  0.703347
4  0.955285  0.114033
5  0.268443  0.416996
6  0.613241  0.327548
7  0.370784  0.359159
8  0.692708  0.659410
9  0.806624  0.875476

How do I check if a string is valid JSON in Python?

I would say parsing it is the only way you can really entirely tell. Exception will be raised by python's json.loads() function (almost certainly) if not the correct format. However, the the purposes of your example you can probably just check the first couple of non-whitespace characters...

I'm not familiar with the JSON that facebook sends back, but most JSON strings from web apps will start with a open square [ or curly { bracket. No images formats I know of start with those characters.

Conversely if you know what image formats might show up, you can check the start of the string for their signatures to identify images, and assume you have JSON if it's not an image.

Another simple hack to identify a graphic, rather than a text string, in the case you're looking for a graphic, is just to test for non-ASCII characters in the first couple of dozen characters of the string (assuming the JSON is ASCII).

How to check if command line tools is installed

Open your terminal and check to see if you have Xcode installed already with this:

xcode-select -p

in return, if you get this:


That means you have that Xcode is installed.

Another way you can check would you if you have "HomeBrew" installed you can use the following command to see if you have Xcode and the version:

brew config

And finally, if you don't have the Xcode follow this link to download the Xcode from the Appstore. Xcode from the App Store.

Good Luck.

When you use 'badidea' or 'thisisunsafe' to bypass a Chrome certificate/HSTS error, does it only apply for the current site?

This is specific for each site. So if you type that once, you will only get through that site and all other sites will need a similar type-through.

It is also remembered for that site and you have to click on the padlock to reset it (so you can type it again):

enter image description here

Needless to say use of this "feature" is a bad idea and is unsafe - hence the name.

You should find out why the site is showing the error and/or stop using it until they fix it. HSTS specifically adds protections for bad certs to prevent you clicking through them. The fact it's needed suggests there is something wrong with the https connection - like the site or your connection to it has been hacked.

The chrome developers also do change this periodically. They changed it recently from badidea to thisisunsafe so everyone using badidea, suddenly stopped being able to use it. You should not depend on it. As Steffen pointed out in the comments below, it is available in the code should it change again though they now base64 encode it to make it more obscure. The last time they changed they put this comment in the commit:

Rotate the interstitial bypass keyword

The security interstitial bypass keyword hasn't changed in two years and awareness of the bypass has been increased in blogs and social media. Rotate the keyword to help prevent misuse.

I think the message from the Chrome team is clear - you should not use it. It would not surprise me if they removed it completely in future.

If you are using this when using a self-signed certificate for local testing then why not just add your self-signed certificate certificate to your computer's certificate store so you get a green padlock and do not have to type this? Note Chrome insists on a SAN field in certificates now so if just using the old subject field then even adding it to the certificate store will not result in a green padlock.

If you leave the certificate untrusted then certain things do not work. Caching for example is completely ignored for untrusted certificates. As is HTTP/2 Push.

HTTPS is here to stay and we need to get used to using it properly - and not bypassing the warnings with a hack that is liable to change and doesn't work the same as a full HTTPS solution.

How to find the most recent file in a directory using .NET, and without looping?

private List<FileInfo> GetLastUpdatedFileInDirectory(DirectoryInfo directoryInfo)
    FileInfo[] files = directoryInfo.GetFiles();
    List<FileInfo> lastUpdatedFile = null;
    DateTime lastUpdate = new DateTime(1, 0, 0);
    foreach (FileInfo file in files)
        if (file.LastAccessTime > lastUpdate)
            lastUpdate = file.LastAccessTime;

    return lastUpdatedFile;

jquery $('.class').each() how many items?

If you are using a version of jQuery that is less than version 1.8 you can use the $('.class').size() which takes zero parameters. See documentation for more information on .size() method.

However if you are using (or plan to upgrade) to 1.8 or greater you can use $('.class').length property. See documentation for more information on .length property.

Delete all items from a c++ std::vector

Is v.clear() not working for some reason?

CodeIgniter - how to catch DB errors?

You must turn debug off for database in config/database.php ->

$db['default']['db_debug'] = FALSE;

It is better for your website security.

ORA-00054: resource busy and acquire with NOWAIT specified

Step 1:

select object_name, s.sid, s.serial#, p.spid 
from v$locked_object l, dba_objects o, v$session s, v$process p
where l.object_id = o.object_id and l.session_id = s.sid and s.paddr = p.addr;

Step 2:

alter system kill session 'sid,serial#'; --`sid` and `serial#` get from step 1

More info:

CSS3 100vh not constant in mobile browser

in my app I do it like so (typescript and nested postcss, so change the code accordingly):

const appHeight = () => {
    const doc = document.documentElement'--app-height', `${window.innerHeight}px`)
window.addEventListener('resize', appHeight)

in your css:

:root {
   --app-height: 100%;

body {
    padding: 0;
    margin: 0;
    overflow: hidden;
    width: 100vw;
    height: 100vh;

    @media not all and (hover:hover) {
        height: var(--app-height);

it works at least on chrome mobile and ipad. What doesn't work is when you add your app to homescreen on iOS and change the orientation a few times - somehow the zoom levels mess with the innerHeight value, I might post an update if I find a solution to it.


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

When you insert ANY variable into HTML, unless you want the browser to interpret the variable itself as HTML, it's best to use htmlspecialchars() on it. Among other things, it prevents hackers from inserting arbitrary HTML in your page.

The value of $_SERVER['PHP_SELF'] is taken directly from the URL entered in the browser. Therefore if you use it without htmlspecialchars(), you're allowing hackers to directly manipulate the output of your code.

For example, if I e-mail you a link to"><script>malicious_code_here()</script><span class=" and you have <form action="<?php echo $_SERVER['PHP_SELF'] ?>">, the output will be:

<form action=""><script>malicious_code_here()</script><span class="">

My script will run, and you will be none the wiser. If you were logged in, I may have stolen your cookies, or scraped confidential info from your page.

However, if you used <form action="<?php echo htmlspecialchars($_SERVER['PHP_SELF']) ?>">, the output would be:

<form action=";&gt;&lt;script&gt;cookie_stealing_code()&lt;/script&gt;&lt;span class=&quot;">

When you submitted the form, you'd have a weird URL, but at least my evil script did not run.

On the other hand, if you used <form action="">, then the output would be the same no matter what I added to my link. This is the option I would recommend.

The Web Application Project [...] is configured to use IIS. The Web server [...] could not be found.

This solution worked for me: Right click the Project and select edit and find the following code as shown below in the picture.

change the <UseIIS>True</UseIIS> to <UseIIS>False</UseIIS>


change the <IISUrl></IISUrl> to <IISUrl>http://localhost/</IISUrl>

csproj screenshot

How to block users from closing a window in Javascript?

If you don't want to display popup for all event you can add conditions like

window.onbeforeunload = confirmExit;
    function confirmExit() {
        if (isAnyTaskInProgress) {
           return "Some task is in progress. Are you sure, you want to close?";

This works fine for me

Installing Java 7 on Ubuntu

I think you should consider Java installation procedure carefully. Following is the detailed process which covers almost all possible failures.

Installing Java with apt-get is easy. First, update the package index:

sudo apt-get update

Then, check if Java is not already installed:

java -version

If it returns "The program java can be found in the following packages", Java hasn't been installed yet, so execute the following command:

sudo apt-get install default-jre

You are fine till now as I assume.

This will install the Java Runtime Environment (JRE). If you instead need the Java Development Kit (JDK), which is usually needed to compile Java applications (for example Apache Ant, Apache Maven, Eclipse and IntelliJ IDEA execute the following command:

sudo apt-get install default-jdk

That is everything that is needed to install Java.

Installing OpenJDK 7:

To install OpenJDK 7, execute the following command:

sudo apt-get install openjdk-7-jre 

This will install the Java Runtime Environment (JRE). If you instead need the Java Development Kit (JDK), execute the following command:

sudo apt-get install openjdk-7-jdk

Installing Oracle JDK:

The Oracle JDK is the official JDK; however, it is no longer provided by Oracle as a default installation for Ubuntu.

You can still install it using apt-get. To install any version, first execute the following commands:

sudo apt-get install python-software-properties
sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update

Then, depending on the version you want to install, execute one of the following commands:

Oracle JDK 7:

sudo apt-get install oracle-java7-installer

Oracle JDK 8:

sudo apt-get install oracle-java8-installer

EPPlus - Read Excel Table

There is no native but what if you use what I put in this post:

How to parse excel rows back to types using EPPlus

If you want to point it at a table only it will need to be modified. Something like this should do it:

public static IEnumerable<T> ConvertTableToObjects<T>(this ExcelTable table) where T : new()
    //DateTime Conversion
    var convertDateTime = new Func<double, DateTime>(excelDate =>
        if (excelDate < 1)
            throw new ArgumentException("Excel dates cannot be smaller than 0.");

        var dateOfReference = new DateTime(1900, 1, 1);

        if (excelDate > 60d)
            excelDate = excelDate - 2;
            excelDate = excelDate - 1;
        return dateOfReference.AddDays(excelDate);

    //Get the properties of T
    var tprops = (new T())

    //Get the cells based on the table address
    var start = table.Address.Start;
    var end = table.Address.End;
    var cells = new List<ExcelRangeBase>();

    //Have to use for loops insteadof worksheet.Cells to protect against empties
    for (var r = start.Row; r <= end.Row; r++)
        for (var c = start.Column; c <= end.Column; c++)
            cells.Add(table.WorkSheet.Cells[r, c]);

    var groups = cells
        .GroupBy(cell => cell.Start.Row)

    //Assume the second row represents column data types (big assumption!)
    var types = groups
        .Select(rcell => rcell.Value.GetType())

    //Assume first row has the column names
    var colnames = groups
        .Select((hcell, idx) => new { Name = hcell.Value.ToString(), index = idx })
        .Where(o => tprops.Select(p => p.Name).Contains(o.Name))

    //Everything after the header is data
    var rowvalues = groups
        .Skip(1) //Exclude header
        .Select(cg => cg.Select(c => c.Value).ToList());

    //Create the collection container
    var collection = rowvalues
        .Select(row =>
            var tnew = new T();
            colnames.ForEach(colname =>
                //This is the real wrinkle to using reflection - Excel stores all numbers as double including int
                var val = row[colname.index];
                var type = types[colname.index];
                var prop = tprops.First(p => p.Name == colname.Name);

                //If it is numeric it is a double since that is how excel stores all numbers
                if (type == typeof(double))
                    if (!string.IsNullOrWhiteSpace(val?.ToString()))
                        //Unbox it
                        var unboxedVal = (double)val;

                        //FAR FROM A COMPLETE LIST!!!
                        if (prop.PropertyType == typeof(Int32))
                            prop.SetValue(tnew, (int)unboxedVal);
                        else if (prop.PropertyType == typeof(double))
                            prop.SetValue(tnew, unboxedVal);
                        else if (prop.PropertyType == typeof(DateTime))
                            prop.SetValue(tnew, convertDateTime(unboxedVal));
                            throw new NotImplementedException(String.Format("Type '{0}' not implemented yet!", prop.PropertyType.Name));
                    //Its a string
                    prop.SetValue(tnew, val);

            return tnew;

    //Send it back
    return collection;

Here is a test method:

public void Table_To_Object_Test()
    //Create a test file
    var fi = new FileInfo(@"c:\temp\Table_To_Object.xlsx");

    using (var package = new ExcelPackage(fi))
        var workbook = package.Workbook;
        var worksheet = workbook.Worksheets.First();
        var ThatList = worksheet.Tables.First().ConvertTableToObjects<ExcelData>();
        foreach (var data in ThatList)
            Console.WriteLine(data.Id + data.Name + data.Gender);


Gave this in the console:


Just be careful if you Id field is an number or string in excel since the class is expecting a string.

Is it possible to use argsort in descending order?

Another way is to use only a '-' in the argument for argsort as in : "df[np.argsort(-df[:, 0])]", provided df is the dataframe and you want to sort it by the first column (represented by the column number '0'). Change the column-name as appropriate. Of course, the column has to be a numeric one.

PHP cURL error code 60

Use this certificate root certificate bundle:

Copy this certificate bundle on your disk. And use this on php.ini

curl.cainfo = "path_to_cert\cacert.pem"

Count occurrences of a char in a string using Bash

also check this out, for example we wanna count t

echo "test" | awk -v RS='t' 'END{print NR-1}'

or in python

python -c 'print "this is for test".count("t")'

or even better, we can make our script dynamic with awk

echo 'test' | awk '{for (i=1 ; i<=NF ; i++) array[$i]++ } END{ for (char in array) print char,array[char]}' FS=""

in this case output is like this :

e 1
s 1
t 2

Standard way to embed version into python package?

There doesn't seem to be a standard way to embed a version string in a python package. Most packages I've seen use some variant of your solution, i.e. eitner

  1. Embed the version in and have generate a module (e.g. containing only version info, that's imported by your package, or

  2. The reverse: put the version info in your package itself, and import that to set the version in

how to use "tab space" while writing in text file

Use "\t". That's the tab space character.

You can find a list of many of the Java escape characters here:

How to change dot size in gnuplot

Use the pointtype and pointsize options, e.g.

plot "./points.dat" using 1:2 pt 7 ps 10  

where pt 7 gives you a filled circle and ps 10 is the size.

See: Plotting data.

Sort a list by multiple attributes?

Several years late to the party but I want to both sort on 2 criteria and use reverse=True. In case someone else wants to know how, you can wrap your criteria (functions) in parenthesis:

s = sorted(my_list, key=lambda i: ( criteria_1(i), criteria_2(i) ), reverse=True)

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use

Don't quote the column filename

mysql> INSERT INTO risks (status, subject, reference_id, location, category, team,    technology, owner, manager, assessment, notes,filename) 
VALUES ('san', 'ss', 1, 1, 1, 1, 2, 1, 1, 'sment', 'notes','santu');

scp via java

plug: sshj is the only sane choice! See these examples to get started: download, upload.

How can I get the current class of a div with jQuery?

var classname=$('#div1').attr('class')

Possible to access MVC ViewBag object from Javascript file?

I don't believe there's currently any way to do this. The Razor engine does not parse Javascript files, only Razor views. However, you can accomplish what you want by setting the variables inside your Razor view:

  var someStringValue = '@(ViewBag.someStringValue)';
  var someNumericValue = @(ViewBag.someNumericValue);
<!-- "someStringValue" and "someNumericValue" will be available in script -->
<script src="js/myscript.js"></script>

As Joe points out in the comments, the string value above will break if there's a single quote in it. If you want to make this completely iron-clad, you'll have to replace all single quotes with escaped single quotes. The problem there is that all of the sudden slashes become an issue. For example, if your string is "foo \' bar", and you replace the single quote, what will come out is "foo \\' bar", and you're right back to the same problem. (This is the age old difficulty of chained encoding.) The best way to handle this is to treat backslashes and quotes as special and make sure they're all escaped:

      var safeStringValue = ViewBag.someStringValue
          .Replace("\\", "\\\\")
          .Replace("'", "\\'");
  var someStringValue = '@(safeStringValue)';

How to get a list column names and datatypes of a table in PostgreSQL?

To get information about the table's column, you can use:

\dt+ [tablename]

To get information about the datatype in the table, you can use:

\dT+ [datatype]

How to remove Left property when position: absolute?

left: initial

This will also set left back to the browser default.

But important to know property: initial is not supported in IE.

How to show one layout on top of the other programmatically in my case?

The answer, given by Alexandru is working quite nice. As he said, it is important that this "accessor"-view is added as the last element. Here is some code which did the trick for me:







<!-- place a FrameLayout (match_parent) as the last child -->


in Java:

final MaterialDialog materialDialog = (MaterialDialog) dialogInterface;

FrameLayout frameLayout = (FrameLayout) materialDialog

        new OnSwipeTouchListener(ShowCardActivity.this) {

Iterating over JSON object in C#

This worked for me, converts to nested JSON to easy to read YAML

    string JSONDeserialized {get; set;}
    public int indentLevel;

    private bool JSONDictionarytoYAML(Dictionary<string, object> dict)
        bool bSuccess = false;

        foreach (string strKey in dict.Keys)
            string strOutput = "".PadLeft(indentLevel * 3) + strKey + ":";
            JSONDeserialized+="\r\n" + strOutput;

            object o = dict[strKey];
            if (o is Dictionary<string, object>)
                JSONDictionarytoYAML((Dictionary<string, object>)o);
            else if (o is ArrayList)
                foreach (object oChild in ((ArrayList)o))
                    if (oChild is string)
                        strOutput = ((string)oChild);
                        JSONDeserialized += strOutput + ",";
                    else if (oChild is Dictionary<string, object>)
                        JSONDictionarytoYAML((Dictionary<string, object>)oChild);
                        JSONDeserialized += "\r\n";  
                strOutput = o.ToString();
                JSONDeserialized += strOutput;


        return bSuccess;



        Dictionary<string, object> JSONDic = new Dictionary<string, object>();
        JavaScriptSerializer js = new JavaScriptSerializer();

          try {

            JSONDic = js.Deserialize<Dictionary<string, object>>(inString);
            JSONDeserialized = "";

            indentLevel = 0;

            return JSONDeserialized;

        catch (Exception)
            return "Could not parse input JSON string";

How can I perform a str_replace in JavaScript, replacing text in JavaScript?

function str_replace($old, $new, $text)
   return ($text+"").split($old).join($new); 

You do not need additional libraries.

What is the difference between :focus and :active?

There are four cases.

  1. By default, active and focus are both off.
  2. When you tab to cycle through focusable elements, they will enter :focus (without active).
  3. When you click on a non-focusable element, it enters :active (without focus).
  4. When you click on a focusable element it enters :active:focus (active and focus simultaneously).


  I cannot be focused.

<div tabindex="0">
  I am focusable.

div:focus {
  background: green;

div:active {
  color: orange;

div:focus:active {
  font-weight: bold;

When the page loads both are in case 1. When you press tab you will focus the second div and see it exhibit case 2. When you click on the first div you see case 3. When you click the second div, you see case 4.

Whether an element is focusable or not is another question. Most are not by default. But, it's safe to assume <a>, <input>, <textarea> are focusable by default.

DataRow: Select cell value by a given column name


DataTable table = new DataTable();
table.Columns.Add("Column#1", typeof(int));
table.Columns.Add("Column#2", typeof(string));
table.Rows.Add(5, "Cell1-1");
table.Rows.Add(130, "Cell2-2");

EDIT: Added more

string cellValue = table.Rows[0].GetCellValueByName<string>("Column#2");

public static class DataRowExtensions
    public static T GetCellValueByName<T>(this DataRow row, string columnName)
        int index = row.Table.Columns.IndexOf(columnName);
        return (index < 0 || index > row.ItemArray.Count()) 
                  ? default(T) 
                  : (T) row[index];        

How to prevent robots from automatically filling up a form?

Just my five cents worth. If the object of this is to stop 99% of robots which sounds pretty good, and if 99% of robots can't run Java-script the best solution that beats all is simply to not use a form that has an action of submit with a post URL.

If the form is controlled via java-script and the java-script collects the form data and then sends it via a HTTP request, no robot can submit the form. Since the submit button would use Java-script to run the code that sends the form.

Multiple commands on a single line in a Windows batch file


echo %time% & dir & echo %time%

This is, from memory, equivalent to the semi-colon separator in bash and other UNIXy shells.

There's also && (or ||) which only executes the second command if the first succeeded (or failed), but the single ampersand & is what you're looking for here.

That's likely to give you the same time however since environment variables tend to be evaluated on read rather than execute.

You can get round this by turning on delayed expansion:

pax> cmd /v:on /c "echo !time! & ping >nul: & echo !time!"

That's needed from the command line. If you're doing this inside a script, you can just use setlocal:

@setlocal enableextensions enabledelayedexpansion
@echo off
echo !time! & ping >nul: & echo !time!

Combine two tables that have no common fields

Very hard when you have to do this with three select statments

I tried all proposed techniques up there but it's in-vain

Please see below script. please advice if you have alternative solution

   select distinct x.best_Achiver_ever,y.Today_best_Achiver ,z.Most_Violator from 

    (SELECT  Top(4) ROW_NUMBER() over (order by tl.username)  AS conj, tl. 
     [username] + '-->' + str(count(*)) as best_Achiver_ever 
    FROM[TiketFollowup].[dbo].N_FCR_Tikect_Log_Archive tl
     group by tl.username
     order by count(*) desc) x
      left outer join 

Top(4) ROW_NUMBER() over (order by tl.username)  as conj, tl.[username] + '-->' + str(count(*)) as Today_best_Achiver
FROM[TiketFollowup].[dbo].[N_FCR_Tikect_Log] tl
where convert(date, tl.stamp, 121) = convert(date,GETDATE(),121)
group by tl.username
order by count(*) desc) y 
on x.conj=y.conj

 left outer join 

select  ROW_NUMBER() over (order by count(*)) as conj,username+ '--> ' + str( count(dbo.IsViolated(stamp))) as Most_Violator from N_FCR_Ticket
where dbo.IsViolated(stamp) = 'violated' and  convert(date,stamp, 121) < convert(date,GETDATE(),121)
group by username
order by count(*) desc) z
on x.conj = z.conj

Bootstrap carousel width and height

I know this is an older post but Bootstrap is still alive and kicking!

Slightly different to @Eduardo's post, I had to modify:

#myCarousel.carousel.slide {
    width: 100%; 
    max-width: 400px; !important

When I only modified .carousel-inner {}, the actual image was fixed size but the left/right controls were displaying incorrectly off to the side of the div.

Append lines to a file using a StreamWriter

Actually only Jon's answer (Sep 5 '11 at 9:37) with BaseStream.Seek worked for my case. Thanks Jon! I needed to append lines to a zip archived txt file.

using (FileStream zipFS = new FileStream(@"c:\Temp\SFImport\",FileMode.OpenOrCreate))
    using (ZipArchive arch = new ZipArchive(zipFS,ZipArchiveMode.Update))
        ZipArchiveEntry entry = arch.GetEntry("testfile.txt");
        if (entry == null)
            entry = arch.CreateEntry("testfile.txt");
        using (StreamWriter sw = new StreamWriter(entry.Open()))
            sw.WriteLine("text content");

How to set gradle home while importing existing project in Android studio

On Arch Linux I could not find it, so I added:

echo $APP_HOME

to /usr/bin/grade (found over which gradle)

The Install dir for me was /usr/share/java/gradle/

How to write an inline IF statement in JavaScript?

FYI, you can compose conditional operators

var a = (truthy) ? 1 : (falsy) ? 2 : 3;

If your logic is sufficiently complex, then you might consider using an IIFE

var a = (function () {
  if (truthy) return 1;
  else if (falsy) return 2;
  return 3;

Of course, if you plan to use this logic more than once, then you aught to encapsulate it in a function to keep things nice and DRY.

Correctly Parsing JSON in Swift 3

First of all never load data synchronously from a remote URL, use always asynchronous methods like URLSession.

'Any' has no subscript members

occurs because the compiler has no idea of what type the intermediate objects are (for example currently in ["currently"]!["temperature"]) and since you are using Foundation collection types like NSDictionary the compiler has no idea at all about the type.

Additionally in Swift 3 it's required to inform the compiler about the type of all subscripted objects.

You have to cast the result of the JSON serialization to the actual type.

This code uses URLSession and exclusively Swift native types

let urlString = ",122.048951"

let url = URL(string: urlString)
URLSession.shared.dataTask(with:url!) { (data, response, error) in
  if error != nil {
  } else {
    do {

      let parsedData = try JSONSerialization.jsonObject(with: data!) as! [String:Any]
      let currentConditions = parsedData["currently"] as! [String:Any]


      let currentTemperatureF = currentConditions["temperature"] as! Double
    } catch let error as NSError {


To print all key / value pairs of currentConditions you could write

 let currentConditions = parsedData["currently"] as! [String:Any]

  for (key, value) in currentConditions {
    print("\(key) - \(value) ")

A note regarding jsonObject(with data:

Many (it seems all) tutorials suggest .mutableContainers or .mutableLeaves options which is completely nonsense in Swift. The two options are legacy Objective-C options to assign the result to NSMutable... objects. In Swift any variable is mutable by default and passing any of those options and assigning the result to a let constant has no effect at all. Further most of the implementations are never mutating the deserialized JSON anyway.

The only (rare) option which is useful in Swift is .allowFragments which is required if if the JSON root object could be a value type(String, Number, Bool or null) rather than one of the collection types (array or dictionary). But normally omit the options parameter which means No options.


Some general considerations to parse JSON

JSON is a well-arranged text format. It's very easy to read a JSON string. Read the string carefully. There are only six different types – two collection types and four value types.

The collection types are

  • Array - JSON: objects in square brackets [] - Swift: [Any] but in most cases [[String:Any]]
  • Dictionary - JSON: objects in curly braces {} - Swift: [String:Any]

The value types are

  • String - JSON: any value in double quotes "Foo", even "123"or "false" – Swift: String
  • Number - JSON: numeric values not in double quotes 123 or 123.0 – Swift: Int or Double
  • Bool - JSON: true or false not in double quotes – Swift: true or false
  • null - JSON: null – Swift: NSNull

According to the JSON specification all keys in dictionaries are required to be String.

Basically it's always recommeded to use optional bindings to unwrap optionals safely

If the root object is a dictionary ({}) cast the type to [String:Any]

if let parsedData = try JSONSerialization.jsonObject(with: data!) as? [String:Any] { ...

and retrieve values by keys with (OneOfSupportedJSONTypes is either JSON collection or value type as described above.)

if let foo = parsedData["foo"] as? OneOfSupportedJSONTypes {

If the root object is an array ([]) cast the type to [[String:Any]]

if let parsedData = try JSONSerialization.jsonObject(with: data!) as? [[String:Any]] { ...

and iterate through the array with

for item in parsedData {

If you need an item at specific index check also if the index exists

if let parsedData = try JSONSerialization.jsonObject(with: data!) as? [[String:Any]], parsedData.count > 2,
   let item = parsedData[2] as? OneOfSupportedJSONTypes {

In the rare case that the JSON is simply one of the value types – rather than a collection type – you have to pass the .allowFragments option and cast the result to the appropriate value type for example

if let parsedData = try JSONSerialization.jsonObject(with: data!, options: .allowFragments) as? String { ...

Apple has published a comprehensive article in the Swift Blog: Working with JSON in Swift


In Swift 4+ the Codable protocol provides a more convenient way to parse JSON directly into structs / classes.

For example the given JSON sample in the question (slightly modified)

let jsonString = """
{"icon": "partly-cloudy-night", "precipProbability": 0, "pressure": 1015.39, "humidity": 0.75, "precip_intensity": 0, "wind_speed": 6.04, "summary": "Partly Cloudy", "ozone": 321.13, "temperature": 49.45, "dew_point": 41.75, "apparent_temperature": 47, "wind_bearing": 332, "cloud_cover": 0.28, "time": 1480846460}

can be decoded into the struct Weather. The Swift types are the same as described above. There are a few additional options:

  • Strings representing an URL can be decoded directly as URL.
  • The time integer can be decoded as Date with the dateDecodingStrategy .secondsSince1970.
  • snaked_cased JSON keys can be converted to camelCase with the keyDecodingStrategy .convertFromSnakeCase

struct Weather: Decodable {
    let icon, summary: String
    let pressure: Double, humidity, windSpeed : Double
    let ozone, temperature, dewPoint, cloudCover: Double
    let precipProbability, precipIntensity, apparentTemperature, windBearing : Int
    let time: Date

let data = Data(jsonString.utf8)
do {
    let decoder = JSONDecoder()
    decoder.dateDecodingStrategy = .secondsSince1970
    decoder.keyDecodingStrategy = .convertFromSnakeCase
    let result = try decoder.decode(Weather.self, from: data)
} catch {

Other Codable sources:

Perform commands over ssh with Python

Works Perfectly...

import paramiko
import time

ssh = paramiko.SSHClient()
ssh.connect('', port=22, username='admin', password='')

stdin, stdout, stderr = ssh.exec_command(" ")

def execute():
       stdin.write('xcommand SystemUnit Boot Action: Restart\n')


Copy table without copying data

Only want to clone the structure of table:


Also wants to copy the data:


How to continue the code on the next line in VBA

If you want to insert this formula =SUMIFS(B2:B10,A2:A10,F2) into cell G2, here is how I did it.

Range("G2")="=sumifs(B2:B10,A2:A10," & _


To split a line of code, add an ampersand, space and underscore.

How can I apply a border only inside a table?

this should work:

table {

table td, table th {
    border: 1px solid black;
    border-collapse: collapse;


i just tried it, no table border. but if i set a table border it is eliminated by the border-collapse.

this is the testfile:

<style type="text/css">
table {
    border-collapse: collapse;
    border-spacing: 0;

table {
    border: 0;
table td, table th {
    border: 1px solid black;

        <th>Heading 1</th>
        <th>Heading 2</th>
        <td>Cell (1,1)</td>
        <td>Cell (1,2)</td>
        <td>Cell (2,1)</td>
        <td>Cell (2,2)</td>
        <td>Cell (3,1)</td>
        <td>Cell (3,2)</td>


How do you determine what technology a website is built on?

yes there are some telltale signs for common CMSs like Drupal, Joomla, Pligg, and RoR etc .. .. ASP.NET stuff is easy to spot too .. but as the framework becomes more obscure it gets harder to deduce ..

What I usually is compare the site i am snooping with another site that I know is built using a particular tech. That sometimes works ..

Provide password to ssh command inside bash script, Without the usage of public keys and Expect

AFAIK there is no possibility beside from using keys or expect if you are using the command line version ssh. But there are library bindings for the most programming languages like C, python, php, ... . You could write a program in such a language. This way it would be possible to pass the password automatically. But note this is of course a security problem as the password will be stored in plain text in that program

Create or write/append in text file

This is working for me, Writing(creating as well) and/or appending content in the same mode.

$fp = fopen("MyFile.txt", "a+") 

Error: select command denied to user '<userid>'@'<ip-address>' for table '<table-name>'

I'm sure the original poster's issue has long since been resolved. However, I had this same issue, so I thought I'd explain what was causing this problem for me.

I was doing a union query with two tables -- 'foo' and 'foo_bar'. However, in my SQL statement, I had a typo: ''

So, instead of telling me that the '' table doesn't exist, the error message indicates that the command was denied -- as though I don't have permissions.

Hope this helps someone.

SQL query to group by day

For oracle you can

group by trunc(created);

as this truncates the created datetime to the previous midnight.

Another option is to

group by to_char(created, 'DD.MM.YYYY');

which achieves the same result, but may be slower as it requires a type conversion.

How to exclude a directory in find . command

find . \( -path '.**/.git' -o -path '.**/.hg' \) -prune -o -name '*.js' -print

The example above finds all *.js files under the current directory, excluding folders .git and .hg, does not matter how deep these .git and .hg folders are.

Note: this also works:

find . \( -path '.*/.git' -o -path '.*/.hg' \) -prune -o -name '*.js' -print

but I prefer the ** notation for consistency with some other tools which would be off topic here.

AttributeError: 'module' object has no attribute


Python is looking for the a object within your module.

Either RENAME that file to something else or use

from __future__ import absolute_import 

at the top of your module.

Java logical operator short-circuiting

Short circuiting means the second operator will not be checked if the first operator decides the final outcome.

E.g. Expression is: True || False

In case of ||, all we need is one of the side to be True. So if the left hand side is true, there is no point in checking the right hand side, and hence that will not be checked at all.

Similarly, False && True

In case of &&, we need both sides to be True. So if the left hand side is False, there is no point in checking the right hand side, the answer has to be False. And hence that will not be checked at all.

Mythical man month 10 lines per developer day - how close on large projects?

I think this comes from from the waterfall development days, where the actual development phase of a project could be as little as 20-30% of the total project time. Take the total lines of code and divide by the entire project time and you'll get around 10 lines/day. Divide by just the coding period, and you'll get closer to what people are quoting.

How to get current foreground activity context in android?

Update 3: There is an official api added for this, please use ActivityLifecycleCallbacks instead.

CSV parsing in Java - working example..?

There is a serious problem with using

String[] strArr=line.split(",");

in order to parse CSV files, and that is because there can be commas within the data values, and in that case you must quote them, and ignore commas between quotes.

There is a very very simple way to parse this:

* returns a row of values as a list
* returns null if you are past the end of the input stream
public static List<String> parseLine(Reader r) throws Exception {
    int ch =;
    while (ch == '\r') {
        //ignore linefeed chars wherever, particularly just before end of file
        ch =;
    if (ch<0) {
        return null;
    Vector<String> store = new Vector<String>();
    StringBuffer curVal = new StringBuffer();
    boolean inquotes = false;
    boolean started = false;
    while (ch>=0) {
        if (inquotes) {
            if (ch == '\"') {
                inquotes = false;
            else {
        else {
            if (ch == '\"') {
                inquotes = true;
                if (started) {
                    // if this is the second quote in a value, add a quote
                    // this is for the double quote in the middle of a value
            else if (ch == ',') {
                curVal = new StringBuffer();
                started = false;
            else if (ch == '\r') {
                //ignore LF characters
            else if (ch == '\n') {
                //end of a line, break out
            else {
        ch =;
    return store;

There are many advantages to this approach. Note that each character is touched EXACTLY once. There is no reading ahead, pushing back in the buffer, etc. No searching ahead to the end of the line, and then copying the line before parsing. This parser works purely from the stream, and creates each string value once. It works on header lines, and data lines, you just deal with the returned list appropriate to that. You give it a reader, so the underlying stream has been converted to characters using any encoding you choose. The stream can come from any source: a file, a HTTP post, an HTTP get, and you parse the stream directly. This is a static method, so there is no object to create and configure, and when this returns, there is no memory being held.

You can find a full discussion of this code, and why this approach is preferred in my blog post on the subject: The Only Class You Need for CSV Files.

How to set layout_weight attribute dynamically from code?

If I someone looking for answer, use this:

LinearLayout.LayoutParams lay = (LinearLayout.LayoutParams) myLayout.getLayoutParams();
lay.weight = 0.5;

If you are initializing your layout from xml file, this will be much more convenient than providing new layout parameters for Linear Layout.

Composer install error - requires ext_curl when it's actually enabled

I ran into the same issue trying to install Dropbox SDK.

CURL was indeed enabled on my system but this meant by the php.ini in the wamp\bin\apache folder.

I simply had to manually edit the php.ini situated in wamp\bin\php, uncomment the extension=php_curl.dll line, restart Wamp and it worked perfectly.

Why there are those 2 php.ini and only one is used is still a mystery for me...

Hope it's helpul to someone!

Android SeekBar setOnSeekBarChangeListener

All answers are correct, but you need to convert a long big fat number into a timer first:

    public String toTimer(long milliseconds){
    String finalTimerString = "";
    String secondsString;
    // Convert total duration into time
    int hours = (int)( milliseconds / (1000*60*60));
    int minutes = (int)(milliseconds % (1000*60*60)) / (1000*60);
    int seconds = (int) ((milliseconds % (1000*60*60)) % (1000*60) / 1000);
    // Add hours if there
    if(hours > 0){
        finalTimerString = hours + ":";
    // Prepending 0 to seconds if it is one digit
    if(seconds < 10){
        secondsString = "0" + seconds;
        secondsString = "" + seconds;}
    finalTimerString = finalTimerString + minutes + ":" + secondsString;
    // return timer string
    return finalTimerString;

And this is how you use it:

public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
textView.setText(String.format("%s", toTimer(progress)));        

Bash Templating: How to build configuration files from templates with Bash?

A longer but more robust version of the accepted answer:

perl -pe 's;(\\*)(\$([a-zA-Z_][a-zA-Z_0-9]*)|\$\{([a-zA-Z_][a-zA-Z_0-9]*)\})?;substr($1,0,int(length($1)/2)).($2&&length($1)%2?$2:$ENV{$3||$4});eg' template.txt

This expands all instances of $VAR or ${VAR} to their environment values (or, if they're undefined, the empty string).

It properly escapes backslashes, and accepts a backslash-escaped $ to inhibit substitution (unlike envsubst, which, it turns out, doesn't do this).

So, if your environment is:


and your template is:

Two ${TARGET} walk into a \\$FOO. \\\\
\\\$FOO says, "Delete C:\\Windows\\System32, it's a virus."
$BAZ replies, "\${NOPE}s."

the result would be:

Two backslashes walk into a \bar. \\
\$FOO says, "Delete C:\Windows\System32, it's a virus."
kenny replies, "${NOPE}s."

If you only want to escape backslashes before $ (you could write "C:\Windows\System32" in a template unchanged), use this slightly-modified version:

perl -pe 's;(\\*)(\$([a-zA-Z_][a-zA-Z_0-9]*)|\$\{([a-zA-Z_][a-zA-Z_0-9]*)\});substr($1,0,int(length($1)/2)).(length($1)%2?$2:$ENV{$3||$4});eg' template.txt

"git checkout <commit id>" is changing branch to "no branch"

If you are branch master and you do a git checkout <SHA>

I'm fairly certain that this causes git to load that commit in a detached state, changing you out of the current branch.

If you want to make changes you can and then you can do a git checkout -b <mynewbranch> to create a new branch based off that commit and any changes you have made.

How to implement "confirmation" dialog in Jquery UI dialog?

I was looking for this to use on link-buttons within an ASP.NET Gridview (GridView Control build in Commands) So the "Confirm" action in the dialog needs to activate a script generated by the Gridview control at run-time. this worked for me:

 $(".DeleteBtnClass").click(function (e) {
     var inlineFunction = $(this).attr("href") + ";";
         buttons: {
             "Yes": function () {
                 eval(inlineFunction); // eval() can be harmful!
                 "No": function () {

Android Studio Checkout Github Error "CreateProcess=2" (Windows)


1) Download git for windows

2) Install downloaded git with default setup

3) From Android Studio close if any project is open then Click on Configure -> Settings -> Version Control -> Git

4) Change Path to Git executable : git.exe to C:\Program Files\Git\cmd\git.exe

5) Apply and Ok

6) Try to clone from Check out project from Version Control

7) Done

enter image description here

How to call function on child component on parent events

you can use key to reload child component using key

<component :is="child1" :filter="filter" :key="componentKey"></component>

If you want to reload component with new filter, if button click filter the child component

reloadData() {            
   this.filter = ['filter1','filter2']
   this.componentKey += 1;  

and use the filter to trigger the function

How to JOIN three tables in Codeigniter

   Check bellow code it`s working fine and  common model function also 
    supported more then one join and also supported  multiple where condition

   //put bellow code in your controller

    $album_id='';//album id 

   //pass join table value in bellow format
    $join_str[0]['table'] = 'Category';
    $join_str[0]['join_table_id'] = 'Category.cat_id';
    $join_str[0]['from_table_id'] = 'Album.cat_id';
    $join_str[0]['join_type'] = 'left';

    $join_str[1]['table'] = 'Soundtrack';
    $join_str[1]['join_table_id'] = 'Soundtrack.album_id';
    $join_str[1]['from_table_id'] = 'Album.album_id';
    $join_str[1]['join_type'] = 'left';

    $selected = "Album.*,Category.cat_name,Category.cat_title,Soundtrack.track_title,Soundtrack.track_url";

   $albumData= $this->common->select_data_by_condition('Album', array('Soundtrack.album_id' => $album_id), $selected, '', '', '', '', $join_str);
                               //call common model function

    if (!empty($albumData)) {
        print_r($albumData); // print album data

    //put bellow code in your common model file

   function select_data_by_condition($tablename, $condition_array = array(), $data = '*', $sortby = '', $orderby = '', $limit = '', $offset = '', $join_str = array()) {
    //if join_str array is not empty then implement the join query
    if (!empty($join_str)) {
        foreach ($join_str as $join) {
            if ($join['join_type'] == '') {
                $this->db->join($join['table'], $join['join_table_id'] . '=' . $join['from_table_id']);
            } else {
                $this->db->join($join['table'], $join['join_table_id'] . '=' . $join['from_table_id'], $join['join_type']);

    //condition array pass to where condition

    //Setting Limit for Paging
    if ($limit != '' && $offset == 0) {
    } else if ($limit != '' && $offset != 0) {
        $this->db->limit($limit, $offset);
    //order by query
    if ($sortby != '' && $orderby != '') {
        $this->db->order_by($sortby, $orderby);

    $query = $this->db->get($tablename);
    //if limit is empty then returns total count
    if ($limit == '') {
    //if limit is not empty then return result array
    return $query->result_array();

Append a Lists Contents to another List C#

Try AddRange-method:


Call child component method from parent class - Angular

You can do this by using @ViewChild for more info check this link

With type selector

child component

  selector: 'child-cmp',
  template: '<p>child</p>'
class ChildCmp {
  doSomething() {}

parent component

  selector: 'some-cmp',
  template: '<child-cmp></child-cmp>',
  directives: [ChildCmp]
class SomeCmp {

  @ViewChild(ChildCmp) child:ChildCmp;

  ngAfterViewInit() {
    // child is set

With string selector

child component

  selector: 'child-cmp',
  template: '<p>child</p>'
class ChildCmp {
  doSomething() {}

parent component

  selector: 'some-cmp',
  template: '<child-cmp #child></child-cmp>',
  directives: [ChildCmp]
class SomeCmp {

  @ViewChild('child') child:ChildCmp;

  ngAfterViewInit() {
    // child is set

How do I check my gcc C++ compiler version for my Eclipse?

Just type

gcc --version

in any terminal near you.. ;-)

Remove an array element and shift the remaining ones

You can use memmove(), but you have to keep track of the array size yourself:

size_t array_size = 5;
int array[5] = {1, 2, 3, 4, 5};

// delete element at index 2
memmove(array + 2, array + 3, (array_size - 2 - 1) * sizeof(int));

In C++, though, it would be better to use a std::vector:

std::vector<int> array;
// initialize array...

// delete element at index 2
array.erase(array.begin() + 2);

jQuery: Check if special characters exists in string

var specialChars = "<>@!#$%^&*()_+[]{}?:;|'\"\\,./~`-="
var check = function(string){
    for(i = 0; i < specialChars.length;i++){
        if(string.indexOf(specialChars[i]) > -1){
            return true
    return false;

if(check($('#Search').val()) == false){
    // Code that needs to execute when none of the above is in the string
    alert('Your search string contains illegal characters.');

unix diff side-to-side results?

You can use vimdiff.


vimdiff file1 file2

How to hash a password

UPDATE: THIS ANSWER IS SERIOUSLY OUTDATED. Please use the recommendations from the instead.

You can either use

var md5 = new MD5CryptoServiceProvider();
var md5data = md5.ComputeHash(data);


var sha1 = new SHA1CryptoServiceProvider();
var sha1data = sha1.ComputeHash(data);

To get data as byte array you could use

var data = Encoding.ASCII.GetBytes(password);

and to get back string from md5data or sha1data

var hashedPassword = ASCIIEncoding.GetString(md5data);

Why do 64-bit DLLs go to System32 and 32-bit DLLs to SysWoW64 on 64-bit Windows?

I believe the intent was to rename System32, but so many applications hard-coded for that path, that it wasn't feasible to remove it.

SysWoW64 wasn't intended for the dlls of 64-bit systems, it's actually something like "Windows on Windows64", meaning the bits you need to run 32bit apps on a 64bit windows.

This article explains a bit:

"Windows x64 has a directory System32 that contains 64-bit DLLs (sic!). Thus native processes with a bitness of 64 find “their” DLLs where they expect them: in the System32 folder. A second directory, SysWOW64, contains the 32-bit DLLs. The file system redirector does the magic of hiding the real System32 directory for 32-bit processes and showing SysWOW64 under the name of System32."

Edit: If you're talking about an installer, you really should not hard-code the path to the system folder. Instead, let Windows take care of it for you based on whether or not your installer is running on the emulation layer.

ImportError: No module named tensorflow

Instead of using the doc's command (conda create -n tensorflow pip python=2.7 # or python=3.3, etc.) which wanted to install python2.7 in the conda environment, and kept erroring out saying the module can't be found when following the installation validation steps, I used conda create -n tensorflow pip python=3 to make sure python3 was installed in the environment.

Doing this, I only had to type python instead of python3 when validating the installation and the error went away.

check if variable empty

You can check if it's not set (or empty) in a number of ways.

if (!$var){ }


if ($var === null){ } // This checks if the variable, by type, IS null.


if (empty($var)){ }

You can check if it's declared with:

if (!isset($var)){ }

Take note that PHP interprets 0 (integer) and "" (empty string) and false as "empty" - and dispite being different types, these specific values are by PHP considered the same. It doesn't matter if $var is never set/declared or if it's declared as $var = 0 or $var = "". So often you compare by using the === operator which compares with respect to data type. If $var is 0 (integer), $var == "" or $var == false will validate, but $var === "" or $var === false will not.

Redirect to new Page in AngularJS using $location

The line

$location.absUrl() == '';

is wrong. First == makes a comparison, and what you are probably trying to do is an assignment, which is with simple = and not double ==.

And because absUrl() getter only. You can use url(), which can be used as a setter or as a getter if you want.

reference :$location

IF statement: how to leave cell blank if condition is false ("" does not work)

Here is what I do


Use the OR condition OR(ISBLANK(cell), cell="")

What is the difference between precision and scale?

Precision is the total number of digits, can be between 1 and 38.
Scale is the number of digits after the decimal point, may also be set as negative for rounding.

NUMBER(7,5): 12.12345
NUMBER(5,0): 12345

More details on the ORACLE website:

How to extract base URL from a string in JavaScript?

This works:


How to solve ADB device unauthorized in Android ADB host device?

You must be prompted in your s4 screen to authorize that computer. You can tell it to remember it. This is for security reasons, occurring in Android 4.4+

input() error - NameError: name '...' is not defined

You could either do:

x = raw_input("enter your name")
print "your name is %s " % x


x = str(input("enter your name"))
print "your name is %s" % x

How to change Git log date formats

After a long time looking for a way to get git log output the date in the format YYYY-MM-DD in a way that would work in less, I came up with the following format:


along with the switch --date=iso.

This will print the date in ISO format (a long one), and then print 14 times the backspace character (0x08), which, in my terminal, effectively removes everything after the YYYY-MM-DD part. For example:

git log --date=iso --pretty=format:'%ad%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%aN %s'

This gives something like:

2013-05-24 bruno This is the message of the latest commit.
2013-05-22 bruno This is an older commit.

What I did was create an alias named l with some tweaks on the format above. It shows the commit graph to the left, then the commit's hash, followed by the date, the shortnames, the refnames and the subject. The alias is as follows (in ~/.gitconfig):

        l = log --date-order --date=iso --graph --full-history --all --pretty=format:'%x08%x09%C(red)%h %C(cyan)%ad%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08 %C(bold blue)%aN%C(reset)%C(bold yellow)%d %C(reset)%s'

How to make audio autoplay on chrome

The video tag can play audio as well. Given the audio tag doesn't seem to be behaving as it should be, you can just use the video tag for audio:

<video autoplay muted id="audio1" src="your.mp3" type="audio/mp3">
    Your browser does not support the <code>video</code> element.
    unmuteButton.addEventListener('click', function() 
            if ( unmuteButton.innerHTML == "unmute" )
                unmuteButton.innerHTML = "mute";
                audio1.muted = false; 
            } else {
                unmuteButton.innerHTML = "unmute";
                audio1.muted = true;