Tutorial by Examples: c

Core Extensions: String Filters

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 ...

Ruby on Rails • ActiveSupport

Core Extensions: String Inflection

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...

Ruby on Rails • ActiveSupport

Newline character is not consumed in typical scanf() call

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\&...

C Language • Common pitfalls

Asset packages

Asset Packages (with the file format of .unitypackage) are a commonly used way of distributing Unity projects to other users. When working with peripherals that have their own SDKs (eg. Oculus), you may be asked to download and import one of these packages. Importing a .unitypackage To import a pa...

unity3d • How to use asset packages

Adding a NOT NULL constraint to existing data

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 ...

Ruby on Rails • ActiveRecord Migrations

Minimal Chart Example

Depending on the version of Chart.JS you are using (the current one being 2.X), the syntax is different to create a minimal example of a bar chart (JSFiddle Demo for 2.X). Chart.js 2.X <html> <body> <canvas id="myChart" width="400" height="400&...

chart.js • Getting started with chart.js

Encoding

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

Go • Base64 Encoding

Encoding to a String

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

Go • Base64 Encoding

Decoding

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...

Go • Base64 Encoding

Decoding a String

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

Go • Base64 Encoding

Adding objects

Anything that needs to happen with data in an IndexedDB database happens in a transaction. There are a few things to note about transactions that are mentioned in the Remarks section at the bottom of this page. We'll use the database we set up in Opening a database. // Create a new readwrite (sinc...

JavaScript • IndexedDB

Initial project workflow

Create a new project dotnet new -l f# Restore any packages listed in project.json dotnet restore A project.lock.json file should be written out. Execute the program dotnet run The above will compile the code if required. The output of the default project created by dotnet new -l f# con...

F# • F# on .NET Core

Espresso custom matchers

Espresso by default has many matchers that help you find views that you need to do some checks or interactions with them. Most important ones can be found in the following cheat sheet: https://google.github.io/android-testing-support-library/docs/espresso/cheatsheet/ Some examples of matchers are...

Android • Testing UI with Espresso

Presenting UI with setContentView

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...

Android • Activity

Natural (comparable) vs explicit (comparator) sorting

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. ...

Java Language • Comparable and Comparator

Adding/Removing an Observer with a Block

Instead of adding an observer with a selector, a block can be used: id testObserver = [[NSNotificationCenter defaultCenter] addObserverForName:@"TestNotification" object:nil ...

iOS • NSNotificationCenter

Rosenbrock function

Think this could example could be better but you get the gist import numpy as np from scipy.optimize import _minimize from scipy import special import matplotlib.pyplot as plt from matplotlib import cm from numpy.random import randn x, y = np.mgrid[-2:2:100j, -2:2:100j] plt.pcolor(x, y, op...

scipy • How to write a Jacobian function for optimize.minimize

Cross Platform OpenGL context creation (using SDL2)

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...

opengl • Getting started with opengl

has_secure_token

Create User Model # Schema: User(token:string, auth_token:string) class User < ActiveRecord::Base has_secure_token has_secure_token :auth_token end Now when you create a new user a token and auth_token are automatically generated user = User.new user.save user.token # => "p...

Ruby on Rails • User Authentication in Rails

Creating an array of variables

$username = 'Hadibut'; $email = '[email protected]'; $variables = compact('username', 'email'); // $variables is now ['username' => 'Hadibut', 'email' => '[email protected]'] This method is often used in frameworks to pass an array of variables between two components.

PHP • Arrays