Tutorial by Examples: co

String#exclude? The inverse of String#include? "hello".exclude? "lo" # => false "hello".exclude? "ol" # => true "hello".exclude? ?h # => false

String#squish Returns a version of the given string without leading or trailing whitespace, and combines all consecutive whitespace in the interior to single spaces. Destructive version squish! operates directly on the string instance. Handles both ASCII and Unicode whitespace. %{ Multi-line ...

String#pluralize Returns of plural form of the string. Optionally takes a count parameter and returns singular form if count == 1. Also accepts a locale parameter for language-specific pluralization. 'post'.pluralize # => "posts" 'octopus'.pluralize # => &quot...

When this program #include <stdio.h> #include <string.h> int main(void) { int num = 0; char str[128], *lf; scanf("%d", &num); fgets(str, sizeof(str), stdin); if ((lf = strchr(str, '\n')) != NULL) *lf = '\0'; printf("%d \"%s\&...

Say you want to add a foreign key company_id to the users table, and you want to have a NOT NULL constraint on it. If you already have data in users, you will have to do this in multiple steps. class AddCompanyIdToUsers < ActiveRecord::Migration def up # add the column with NULL allowed ...

const foobar = `foo bar` encoding := base64.StdEncoding encodedFooBar := make([]byte, encoding.EncodedLen(len(foobar))) encoding.Encode(encodedFooBar, []byte(foobar)) fmt.Printf("%s", encodedFooBar) // Output: Zm9vIGJhcg== Playground

str := base64.StdEncoding.EncodeToString([]byte(`foo bar`)) fmt.Println(str) // Output: Zm9vIGJhcg== Playground

encoding := base64.StdEncoding data := []byte(`Zm9vIGJhcg==`) decoded := make([]byte, encoding.DecodedLen(len(data))) n, err := encoding.Decode(decoded, data) if err != nil { log.Fatal(err) } // Because we don't know the length of the data that is encoded // (only the max length), we n...

decoded, err := base64.StdEncoding.DecodeString(`biws`) if err != nil { log.Fatal(err) } fmt.Printf("%s", decoded) // Output: n,, Playground

Activity class takes care of creating a window for you in which you can place your UI with setContentView. There are three setContentView methods: setContentView(int layoutResID) - Set the activity content from a layout resource. setContentView(View view) - Set the activity content to an explic...

There are two Collections.sort() methods: One that takes a List<T> as a parameter where T must implement Comparable and override the compareTo() method that determines sort order. One that takes a List and a Comparator as the arguments, where the Comparator determines the sort order. ...

Creating a Window with OpenGL context (extension loading through GLEW): #define GLEW_STATIC #include <GL/glew.h> #include <SDL2/SDL.h> int main(int argc, char* argv[]) { SDL_Init(SDL_INIT_VIDEO); /* Initialises Video Subsystem in SDL */ /* Setting up OpenGL version a...

The Null-Coalescing operator ?? will return the left-hand side when not null. If it is null, it will return the right-hand side. object foo = null; object bar = new object(); var c = foo ?? bar; //c will be bar since foo was null The ?? operator can be chained which allows the removal of if...

Databings are essential for working with XAML. The XAML dialect for UWP apps provides a type of binding: the {x:Bind} markup extension. Working with {Binding XXX} and {x:Bind XXX} is mostly equivalent, with the difference that the x:Bind extension works at compile time, which enables better debuggi...

Knitr is an R package that allows us to intermingle R code with LaTeX code. One way to achieve this is inline code chunks. This apporach is demonstrated below. # r-noweb-file.Rnw \documentclass{article} \begin{document} This is an Rnw file (R noweb). It contains a combination of LateX and ...

Knitr is an R package that allows us to intermingle R code with LaTeX code. One way to achieve this is internal code chunks. This apporach is demonstrated below. # r-noweb-file.Rnw \documentclass{article} \begin{document} This is an Rnw file (R noweb). It contains a combination of LateX a...

Command line scripts inside python packages are common. You can organise your package in such a way that when a user installs the package, the script will be available on their path. If you had the greetings package which had the command line script hello_world.py. greetings/ greetings/ ...

The Composite pattern is a design pattern that allows to treat a group of objects as a single instance of an object. It is one of the Gang of Four's structural design patterns. Example below demonstrate how Composite can be used to log to multiple places using single Log invocation. This approach a...

MySQL provides the following arithmetic operators OperatorNameExample+AdditionSELECT 3+5; -> 8 SELECT 3.5+2.5; -> 6.0 SELECT 3.5+2; -> 5.5-SubtractionSELECT 3-5; -> -2*MultiplicationSELECT 3 * 5; -> 15/DivisionSELECT 20 / 4; -> 5 SELECT 355 / 113; -> 3.1416 SELECT 10.0 / 0; -...

Pi The following returns the value of PI formatted to 6 decimal places. The actual value is good to DOUBLE; SELECT PI(); -> 3.141593