Tutorial by Examples: le

A while loop executes statements repeatedly until the given condition evaluates to false. This control statement is used when it is not known, in advance, how many times a block of code is to be executed. For example, to print all the numbers from 0 up to 9, the following code can be used: int i =...

This type of Singleton is thread safe, and prevents unnecessary locking after the Singleton instance has been created. Java SE 5 public class MySingleton { // instance of class private static volatile MySingleton instance = null; // Private constructor private MySingleton()...

When defining discriminated unions you can name elements of tuple types and use these names during pattern matching. type Shape = | Circle of diameter:int | Rectangle of width:int * height:int let shapeIsTenWide = function | Circle(diameter=10) | Rectangle(width=10) -> t...

Clicking the Select an element in the page to inspect it button in the upper left corner of the Elements tab in Chrome or Inspector tab in Firefox, available from Developer Tools, and then clicking on a element of the page highlights the element and assigns it to the $0 variable. Elements inspecto...

Classes in MATLAB are divided into two major categories: value classes and handle classes. The major difference is that when copying an instance of a value class, the underlying data is copied to the new instance, while for handle classes the new instance points to the original data and changing val...

SELECT Id, FName, LName, (SELECT COUNT(*) FROM Cars WHERE Cars.CustomerId = Customers.Id) AS NumberOfCars FROM Customers

A simple program that writes "Hello, world!" to test.txt, reads back the data, and prints it out. Demonstrates simple file I/O operations. package main import ( "fmt" "io/ioutil" ) func main() { hello := []byte("Hello, world!") //...

package main import ( "fmt" "io/ioutil" ) func main() { files, err := ioutil.ReadDir(".") if err != nil { panic(err) } fmt.Println("Files and folders in the current directory:") for _, fileInfo := range fi...

To create a pure JSON table you need to provide a single field with the type JSONB: CREATE TABLE mytable (data JSONB NOT NULL); You should also create a basic index: CREATE INDEX mytable_idx ON mytable USING gin (data jsonb_path_ops); At this point you can insert data in to the table and que...

Taking a complex JSON document in a table: CREATE TABLE mytable (data JSONB NOT NULL); CREATE INDEX mytable_idx ON mytable USING gin (data jsonb_path_ops); INSERT INTO mytable VALUES($$ { "name": "Alice", "emails": [ "[email protected]", ...

The current stable version of scikit-learn requires: Python (>= 2.6 or >= 3.3), NumPy (>= 1.6.1), SciPy (>= 0.9). For most installation pip python package manager can install python and all of its dependencies: pip install scikit-learn However for linux systems it is recomm...

You can require a generic type to extend multiple upper bounds. Example: we want to sort a list of numbers but Number doesn't implement Comparable. public <T extends Number & Comparable<T>> void sortNumbers( List<T> n ) { Collections.sort( n ); } In this example T must...

Responding to Editing Notifications textViewShouldBeginEditing(_:) textViewDidBeginEditing(_:) textViewShouldEndEditing(_:) textViewDidEndEditing(_:) Responding to Text Changes textView(_:shouldChangeTextIn:replacementText:) textViewDidChange(_:) Responding to URL textView(_: UITe...

Auto-implemented properties were introduced in C# 3. An auto-implemented property is declared with an empty getter and setter (accessors): public bool IsValid { get; set; } When an auto-implemented property is written in your code, the compiler creates a private anonymous field that can only be...

Lets assume we have some Film model: public class Film { public string Title { get; set; } public string Category { get; set; } public int Year { get; set; } } Group by Category property: foreach (var grp in films.GroupBy(f => f.Category)) { var groupCategory = grp.Key; ...

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...

This is the primary purpose of cat. cat file1 file2 file3 > file_all cat can also be used similarly to concatenate files as part of a pipeline, e.g. cat file1 file2 file3 | grep foo

You can use traits to modify methods of a class, using traits in stackable fashion. The following example shows how traits can be stacked. The ordering of the traits are important. Using different order of traits, different behavior is achieved. class Ball { def roll(ball : String) = println(&q...

If you need to remove one or more elements from a slice, or if you need to work with a sub slice of another existing one; you can use the following method. Following examples uses slice of int, but that works with all type of slice. So for that, we need a slice, from witch we will remove some ...

A while loop will evaluate a condition and if true will perform an action. As long as the condition evaluates to true the action will continue to be performed. while(condition){ code_block } The following example creates a loop that will count down from 10 to 0 $i = 10 while($i -ge 0){ ...