Tutorial by Examples: for

>>> '{0:.0f}'.format(42.12345) '42' >>> '{0:.1f}'.format(42.12345) '42.1' >>> '{0:.3f}'.format(42.12345) '42.123' >>> '{0:.5f}'.format(42.12345) '42.12345' >>> '{0:.7f}'.format(42.12345) '42.1234500' Same hold for other way of referenc...

By default, Django renders ForeignKey fields as a <select> input. This can cause pages to be load really slowly if you have thousands or tens of thousand entries in the referenced table. And even if you have only hundreds of entries, it is quite uncomfortable to look for a particular entry amo...

Category theory is a modern mathematical theory and a branch of abstract algebra focused on the nature of connectedness and relation. It is useful for giving solid foundations and common language to many highly reusable programming abstractions. Haskell uses Category theory as inspiration for some o...

There are several ways to format and get a string as a result. The .NET way is by using String.Format or StringBuilder.AppendFormat: open System open System.Text let hello = String.Format ("Hello {0}", "World") // return a string with "Hello World" let builder...

It is possible to effectively apply a function (cb) which returns a promise to each element of an array, with each element waiting to be processed until the previous element is processed. function promiseForEach(arr, cb) { var i = 0; var nextPromise = function () { if (i >= arr.leng...

Let's say we have the following function: (defn nat-num-count [nums] (count (remove neg? nums))) We can write a spec for this function by defining a function spec of the same name: (clojure.spec/fdef nat-num-count :args (s/cat :nums (s/coll-of number?)) :ret integer? ...

$ man -w find /usr/share/man/man1/find.1.gz $ man -w printf /usr/share/man/man1/printf.1.gz $ man -w man /usr/share/man/man1/man.1.gz

You can search for man pages containing a particular string in their description using: man -k <string> For example: man -k unzip Might return: man -k unzip IO::Uncompress::Bunzip2(3pm) - Read bzip2 files/buffers IO::Uncompress::Gunzip(3pm) - Read RFC 1952 files/buffers IO::Uncom...

After launching Visual Studio 2015, go to File → New → Project. In the New Project dialog box, browse in the templates tree to Visual C# → Windows → Universal and select Blank App (Universal Windows). Next, we need to fill the form to describe the Application: Name: this is the name of the appli...

PHP provides an alternative syntax for some control structures: if, while, for, foreach, and switch. When compared to the normal syntax, the difference is, that the opening brace is replaced by a colon (:) and the closing brace is replaced by endif;, endwhile;, endfor;, endforeach;, or endswitch;, ...

for loops are typically used when you have a piece of code which you want to repeat a given number of times. for ($i = 1; $i < 10; $i++) { echo $i; } Outputs: 123456789 For detailed information, see the Loops topic.

foreach is a construct, which enables you to iterate over arrays and objects easily. $array = [1, 2, 3]; foreach ($array as $value) { echo $value; } Outputs: 123. To use foreach loop with an object, it has to implement Iterator interface. When you iterate over associative arrays: $arra...

You must be very careful when providing a forwarding reference overload as it may match too well: struct A { A() = default; // #1 A(A const& ) = default; // #2 template <class T> A(T&& ); // #3 }; The intent here was that A is c...

Objective-C //set off-image mySwitch.offImage = [UIImage imageNamed:@"off_image"]; [mySwitch setOffImage:[UIImage imageNamed:@"off_image"]]; //set on-image mySwitch.onImage = [UIImage imageNamed:@"on_image"]; [mySwitch setOnImage:[UIImage imageNamed:@"on_im...

.htaccess can be used to force your HTTP site to redirect to HTTPS. Here's a quick way that doesn't require editing the code for your domain: RewriteEngine On RewriteCond %{HTTPS} =off RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301] Warning: The code above assumes that you can tr...

SP.SOD.executeOrDelayUntilScriptLoaded(showDialog,"sp.js"); function showDialog(){ var options = SP.UI.$create_DialogOptions(); options.url = "/mySite/lists/myList/NewForm.aspx"; options.dialogReturnValueCallback = myCallBackFunction; SP.UI.ModalDialog.show...

SP.SOD.executeOrDelayUntilScriptLoaded(showUserInfo,"sp.js"); function showUserInfo(){ var clientContext = new SP.ClientContext(); var user = clientContext.get_web().get_currentUser(); clientContext.load(user); clientContext.executeQueryAsync(function(){ ...

Note: You cannot develop react-native apps for iOS on Windows, only react-native android apps. The official setup docs for react-native on windows can be found here. If you need more details there is a granular guide here. Tools/Environment Windows 10 command line tool (eg Powershell or window...

Converting an NSDate object to string is just 3 steps. 1. Create an NSDateFormatter object Swift let dateFormatter = NSDateFormatter() Swift 3 let dateFormatter = DateFormatter() Objective-C NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init]; 2. Set the date format in whic...

Array.prototype.map(): Returns a new array with the results of calling a provided function on every element in the original array. The following code example takes an array of persons and creates a new array containing persons with a 'fullName' property var personsArray = [ { id: 1, f...