Tutorial by Examples: er

Python 2.x2.3 Objects of different types can be compared. The results are arbitrary, but consistent. They are ordered such that None is less than anything else, numeric types are smaller than non-numeric types, and everything else is ordered lexicographically by type. Thus, an int is less than a st...

def say_hello_to(name) puts "Hello #{name}" end say_hello_to('Charles') # Hello Charles

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

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...

def welcome_guests(*guests) guests.each { |guest| puts "Welcome #{guest}!" } end welcome_guests('Tom') # Welcome Tom! welcome_guests('Rob', 'Sally', 'Lucas') # Welcome Rob! # Welcome Sally! # W...

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...

Generate a certificate In order to run a HTTPS server, a certificate is necessary. Generating a self-signed certificate with openssl is done by executing this command: openssl req -x509 -newkey rsa:4096 -sha256 -nodes -keyout key.pem -out cert.pem -subj "/CN=example.com" -days 3650` T...

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...

Basic usage: PropertyInfo prop = myInstance.GetType().GetProperty("myProperty"); // get the value myInstance.myProperty object value = prop.GetValue(myInstance); int newValue = 1; // set the value myInstance.myProperty to newValue prop.setValue(myInstance, newValue); Setting rea...

This example use the default boxplot() function and the irisdata frame. > head(iris) Sepal.Length Sepal.Width Petal.Length Petal.Width Species 1 5.1 3.5 1.4 0.2 setosa 2 4.9 3.0 1.4 0.2 setosa 3 4.7 3.2 ...

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...

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...

Inner join returns only those records/rows that match/exists in both the tables based on one or more conditions (specified using ON keyword). It is the most common type of join. The general syntax for inner join is: SELECT * FROM table_1 INNER JOIN table_2 ON table_1.column_name = table_2.col...

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...

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 ...

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...

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...

slice1 := []string{"!"} slice2 := []string{"Hello", "world"} slice := append(slice1, slice2...) Run in the Go Playground

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 ...