Tutorial by Examples: u

Multiple required parameters

def greet(greeting, name) puts "#{greeting} #{name}" end greet('Hi', 'Sophie') # Hi Sophie

Ruby Language • Methods

def make_animal_sound(sound = 'Cuack') puts sound end make_animal_sound('Mooo') # Mooo make_animal_sound # Cuack It's possible to include defaults for multiple arguments: def make_animal_sound(sound = 'Cuack', volume = 11) play_sound(sound, volume) end make_animal_so...

Ruby Language • Methods

Basic String manipulation

fn main() { // Statically allocated string slice let hello = "Hello world"; // This is equivalent to the previous one let hello_again: &'static str = "Hello world"; // An empty String let mut string = String::new(); // An empty String ...

Rust • Strings

Traits to facilitate horizontal code reuse

Let's say we have an interface for logging: interface Logger { function log($message); } Now say we have two concrete implementations of the Logger interface: the FileLogger and the ConsoleLogger. class FileLogger implements Logger { public function log($message) { // Append...

PHP • Traits

Calling a function from another C file

foo.h #ifndef FOO_DOT_H /* This is an "include guard" */ #define FOO_DOT_H /* prevents the file from being included twice. */ /* Including a header file twice causes all kinds */ /* of interesting problems.*/ /** * This is a functi...

C Language • Declarations

Using a Global Variable

Use of global variables is generally discouraged. It makes your program more difficult to understand, and harder to debug. But sometimes using a global variable is acceptable. global.h #ifndef GLOBAL_DOT_H /* This is an "include guard" */ #define GLOBAL_DOT_H /** * This tells ...

C Language • Declarations

onUpgrade() method

SQLiteOpenHelper is a helper class to manage database creation and version management. In this class, the onUpgrade() method is responsible for upgrading the database when you make changes to the schema. It is called when the database file already exists, but its version is lower than the one spec...

Android • SQLite

SUM

Sum function sum the value of all the rows in the group. If the group by clause is omitted then sums all the rows. select sum(salary) TotalSalary from employees; TotalSalary2500 select DepartmentId, sum(salary) TotalSalary from employees group by DepartmentId; DepartmentIdTotalSalary12000...

SQL • Functions (Aggregate)

Forcing a static constructor to be called

While static constructors are always called before the first usage of a type it's sometimes useful to be able to force them to be called and the RuntimeHelpers class provide an helper for it: using System.Runtime.CompilerServices; // ... RuntimeHelpers.RunClassConstructor(typeof(Foo).TypeHand...

C# Language • Constructors and Finalizers

Installation or Setup

To prepare your web site or web application to use Kendo UI, simply add the style and script files in the <head> section of your page. CDN services are provided for the minified versions of official Kendo UI releases, for both HTTP and HTTPS protocols. JQuery is also required to use Kendo UI...

kendo-ui • Getting started with kendo-ui

Creating a new program using Mono

First install Mono by going through the install instructions for the platform of your choice as described in their installation section. Mono is available for Mac OS X, Windows and Linux. After installation is done, create a text file, name it HelloWorld.cs and copy the following content into it: ...

C# Language • Getting started with C# Language

Using pointer parameters to return multiple values

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...

C Language • Function Parameters

Multiple Inheritance

Multiple inheritance is a feature that allows one class to inherit from multiple classes(i.e., more than one parent). Ruby does not support multiple inheritance. It only supports single-inheritance (i.e. class can have only one parent), but you can use composition to build more complex classes using...

Ruby Language • Inheritance

Installation or Setup

Executable File Download the .exe from http://dev.sitecore.net/ and double-click to start. This .exe will do everything for you - attach databases, modify host file, and set folder permissions. The only downside is that it leaves an entry in the registry under [HKEY_LOCAL_MACHINE\SOFTWARE\Sitecore...

sitecore • Getting started with sitecore

Construct a string from Array

The String.Join method will help us to construct a string From array/list of characters or string. This method accepts two parameters. The first one is the delimiter or the separator which will help you to separate each element in the array. And the second parameter is the Array itself. String from...

C# Language • Common String Operations

Formatting using ToString

Usually we are using String.Format method for formatting purpose, the.ToString is usually used for converting other types to string. We can specify the format along with the ToString method while conversion is taking place, So we can avoid an additional Formatting. Let Me Explain how it works with d...

C# Language • Common String Operations

Outer Join

Left Outer Join LEFT JOIN returns all rows from the left table, matched to rows from the right table where the ON clause conditions are met. Rows in which the ON clause is not met have NULL in all of the right table's columns. The syntax of a LEFT JOIN is: SELECT * FROM table_1 AS t1 LEFT JOIN ta...

Microsoft SQL Server • Join

Manually triggering GC

You can manually trigger the Garbage Collector by calling System.gc(); However, Java does not guarantee that the Garbage Collector has run when the call returns. This method simply "suggests" to the JVM (Java Virtual Machine) that you want it to run the garbage collector, but does not ...

Java Language • Java Memory Management

Enums with Abstract Methods

Enums can define abstract methods, which each enum member is required to implement. enum Action { DODGE { public boolean execute(Player player) { return player.isAttacking(); } }, ATTACK { public boolean execute(Player player) { re...

Java Language • Enums

Default Values for Properties

Setting a default value can be done by using Initializers (C#6) public class Name { public string First { get; set; } = "James"; public string Last { get; set; } = "Smith"; } If it is read only you can return values like this: public class Name { pu...

C# Language • Properties