Tutorial by Examples: is

Returns unique values from an IEnumerable. Uniqueness is determined using the default equality comparer. int[] array = { 1, 2, 3, 4, 2, 5, 3, 1, 2 }; var distinct = array.Distinct(); // distinct = { 1, 2, 3, 4, 5 } To compare a custom data type, we need to implement the IEquatable<T> i...

Map<String, String> num = new HashMap<>(); num.put("one", "first"); if (num.containsKey("one")) { System.out.println(num.get("one")); // => first } Maps can contain null values For maps, one has to be carrefull not to confuse &quot...

The following code snippet shows how to open the Google Play Store Listing of your app in a safe way. Usually you want to use it when asking the user to leave a review for your app. private void openPlayStore() { String packageName = getPackageName(); Intent playStoreIntent = new Intent(I...

To get a verbose list of all devices connected to adb, write the following command in your terminal: adb devices -l Example Output List of devices attached ZX1G425DC6 device usb:336592896X product:shamu model:Nexus_6 device:shamu 013e4e127e59a868 device usb:337641472X produc...

Composer is a dependency/package manager for PHP. It can be used to install, keep track of, and update your project dependencies. Composer also takes care of autoloading the dependencies that your application relies on, letting you easily use the dependency inside your project without worrying about...

Ember comes with a built in helper that will provide computed properties for the status of an asynchronous task. Pros Built in – no need for an addon. Can be managed in the life cycle of a component. Provides convenient state properties that can drive the template logic. Cons Must be wra...

Units of measure are additional type annotations that can be added to floats or integers. They can be used to verify at compile time that calculations are using units consistently. To define annotations: [<Measure>] type m // meters [<Measure>] type s // seconds [<Measure>] typ...

While many people think that ^ means the start of a string, it actually means start of a line. For an actual start of string anchor use, \A. The string hello\nworld (or more clearly) hello world Would be matched by the regular expressions ^h, ^w and \Ah but not by \Aw

PowerShell comparison operators are comprised of a leading dash (-) followed by a name (eq for equal, gt for greater than, etc...). Names can be preceded by special characters to modify the behavior of the operator: i # Case-Insensitive Explicit (-ieq) c # Case-Sensitive Explicit (-ceq) Case-I...

class Animal def method_missing(method, *args, &block) say, speak = method.to_s.split("_") if say == "say" speak else super end end end => a = Animal.new => a.say_moo => "moo" => a.shout_moo => NoMethodE...

To remove existing column name from users table, run the command: rails generate migration RemoveNameFromUsers name:string This will generate the following migration: class RemoveNameFromUsers < ActiveRecord::Migration[5.0] def change remove_column :users, :name, :string end end ...

asp:ListView introduced in ASP.NET WebForms framework 3.5 is the most flexible of all DataPresentation Controls in the framework. An example of Grouping using ListView (which will come handy as an image gallery) Objective: To display three images in a row using asp:ListView Markup <asp:ListVie...

To catch a long click and use it you need to provide appropriate listener to button: View.OnLongClickListener listener = new View.OnLongClickListener() { public boolean onLongClick(View v) { Button clickedButton = (Button) v; String buttonText = clickedButton.getText().toStri...

Discriminated unions in F# offer a a way to define types which may hold any number of different data types. Their functionality is similar to C++ unions or VB variants, but with the additional benefit of being type safe. // define a discriminated union that can hold either a float or a string type...

Whenever you attempt to retrieve a certain field from a class like so: $animal = new Animal(); $height = $animal->height; PHP invokes the magic method __get($name), with $name equal to "height" in this case. Writing to a class field like so: $animal->height = 10; Will invoke...

The filter or map functions should often be replaced by list comprehensions. Guido Van Rossum describes this well in an open letter in 2005: filter(P, S) is almost always written clearer as [x for x in S if P(x)], and this has the huge advantage that the most common usages involve predicates tha...

The following code is for iOS 8 and lower for creating a login alert. // Create the UIAlertView var loginAlertView = new UIAlertView(title, message, null, cancelTitle, okTitle); // Setting the AlertViewStyle to UIAlertViewStyle.LoginAndPasswordInput loginAlertView.AlertViewStyle = UIAlertViewS...

This a basic example aimed at new users. It does not focus on explaining the difference between char and cellstring. It might happen that you want to get rid of the ' in your strings, although you never added them. In fact, those are artifacts that the command window uses to distinguish between ...

5.0 In PowerShell 5.0+ you can list available constructors by calling the static new-method without parentheses. PS> [DateTime]::new OverloadDefinitions ------------------- datetime new(long ticks) datetime new(long ticks, System.DateTimeKind kind) datetime new(int year, int month, int d...

A list in Erlang is a sequence of zero or more Erlang terms, implemented as a singly linked list. Each element in the list can be any type of term (any data type). 1> [1,2,3]. [1,2,3] 2> [wow,1,{a,b}]. [wow,1,{a,b}] The list's head is the first element of the list. The list's tail...