Tutorial by Examples: re

A common pattern in C, to easily imitate returning multiple values from a function, is to use pointers. #include <stdio.h> void Get( int* c , double* d ) { *c = 72; *d = 175.0; } int main(void) { int a = 0; double b = 0.0; Get( &a , &b ); pr...

The Clojure community puts a large emphasis on interactive development, so quite a lot of interaction with Clojure happens within a REPL (read-eval-print-loop). When you input an expression into it, Clojure reads it, evaluates it, and prints the result of the evaluation, all in a loop. You should b...

An example that uses Parallel.ForEach loop to ping a given array of website urls. static void Main() { string [] urls = { "www.stackoverflow.com", "www.google.net", "www.facebook.com", "www.twitter.com" ...

This example aims to describe how one can utilize git rebase in interactive mode. It is expected that one has a basic understanding of what git rebase is and what it does. Interactive rebase is initiated using following command: git rebase -i The -i option refers to interactive mode. Using inte...

Enums have been backported from Python 3.4 to Python 2.4 through Python 3.3. You can get this the enum34 backport from PyPI. pip install enum34 Creation of an enum is identical to how it works in Python 3.4+ from enum import Enum class Color(Enum): red = 1 green = 2 blue = 3 ...

This Makefile will cross compile and zip up executables for Windows, Mac and Linux (ARM and x86). # Replace demo with your desired executable name appname := demo sources := $(wildcard *.go) build = GOOS=$(1) GOARCH=$(2) go build -o build/$(appname)$(3) tar = cd build && tar -cvzf $...

Case statements can be combined with if expressions to provide extra logic when pattern matching. def checkSign(x: Int): String = { x match { case a if a < 0 => s"$a is a negative number" case b if b > 0 => s"$b is a positive number" case c ...

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()...

As shown in Declaring Namespaces, we can define a class in a namespace as follows: namespace MyProject\Shapes; class Rectangle { ... } To reference this class the full path (including the namespace) needs to be used: $rectangle = new MyProject\Shapes\Rectangle(); This can be shortened by ...

Use a subquery to filter the result set. For example this will return all employees with a salary equal to the highest paid employee. SELECT * FROM Employees WHERE Salary = (SELECT MAX(Salary) FROM Employees)

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...

Creation of a Button is simple: Button sampleButton = new Button(); This will create a new Button without any text or graphic inside. If you want to create a Button with a text, simply use the constructor that takes a String as parameter (which sets the textProperty of the Button): Button samp...

Problem: Create a String containing n repetitions of a String s. The trivial approach would be repeatedly concatenating the String final int n = ... final String s = ... String result = ""; for (int i = 0; i < n; i++) { result += s; } This creates n new string instances ...

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...

You have started an interactive rebase. In the editor where you pick your commits, you decide that something is going wrong (for example a commit is missing, or you chose the wrong rebase destination), and you want to abort the rebase. To do this, simply delete all commits and actions (i.e. all lin...

Definition In software development, a breakpoint is an intentional stopping or pausing place in a program, put in place for debugging purposes. More generally, a breakpoint is a means of acquiring knowledge about a program during its execution. During the interruption, the programmer inspects th...

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 jump back to a previous commit, first find the commit's hash using git log. To temporarily jump back to that commit, detach your head with: git checkout 789abcd This places you at commit 789abcd. You can now make new commits on top of this old commit without affecting the branch your head is...