Tutorial by Examples: ar

Get all combinations / permutations of an array

The permutation method, when called with a block yields a two dimensional array consisting of all ordered sequences of a collection of numbers. If this method is called without a block, it will return an enumerator. To convert to an array, call the to_a method. ExampleResult[1,2,3].permutation#&lt...

Ruby Language • Arrays

HTML markup

example input: <html> <head> <title>the title</title> <link href='css/app.css' type='text/css' rel='stylesheet'> <script src='js/app.js'></script> </head> <body> <h1>header</h1> <div> &l...

DOM • Getting started with DOM

Sort a dynamic array via generic TArray.Sort

uses System.Generics.Collections, { TArray } System.Generics.Defaults; { TComparer<T> } var StringArray: TArray<string>; { Also works with "array of string" } ... { Sorts the array case insensitive } TArray.Sort<string>(StringArray, TComparer<string>...

Embarcadero Delphi • Generics

Creating a data type with value constructor parameters

Value constructors are functions that return a value of a data type. Because of this, just like any other function, they can take one or more parameters: data Foo = Bar String Int | Biz String Let's check the type of the Bar value constructor. :t Bar prints Bar :: String -> Int -> Foo...

Haskell Language • Creating Custom Data Types

Creating a data type with type parameters

Type constructors can take one or more type parameters: data Foo a b = Bar a b | Biz a b Type parameters in Haskell must begin with a lowercase letter. Our custom data type is not a real type yet. In order to create values of our type, we must substitute all type parameters with actual types. Be...

Haskell Language • Creating Custom Data Types

Duplicate Parameters

Strict mode does not allow you to use duplicate function parameter names. function foo(bar, bar) {} // No error. bar is set to the final argument when called "use strict"; function foo(bar, bar) {}; // SyntaxError: duplicate formal argument bar

JavaScript • Strict mode

Advanced use of SetTimer: Calling the same function with different parameters

This is an example of something that would have been straight up impossible with labels. If you execute the same label multiple times at the same time and they rely on variables that are being defined within them, they very likely interfere and cause unexpected behavior. Here is how to do it with f...

AutoHotkey • Use functions instead of labels

Pipe Forward and Backward

Pipe operators are used to pass parameters to a function in a simple and elegant way. It allows to eliminate intermediate values and make function calls easier to read. In F#, there are two pipe operators: Forward (|>): Passing parameters from left to right let print message = print...

F# • Functions

List-appending to a nested dictionary

If we have this dictionary: set alpha {alice {items {}} bob {items {}} claudia {items {}} derek {items {}}} And want to add "fork" and "peanut" to Alice's items, this code won't work: dict lappend alpha alice items fork peanut dict get $alpha alice # => items {} items f...

tcl • Dictionaries

Declaring background page in the manifest

There are two ways to register a background page in the extension manifest. The scripts property In the common case, a background page doesn't require any HTML markup. We can register these kinds of background pages using the scripts property. In this case, a background page will be generated...

google-chrome-extension • Background pages

Sorting built-in arrays

The sort algorithm sorts a sequence defined by two iterators. This is enough to sort a built-in (also known as c-style) array. C++11 int arr1[] = {36, 24, 42, 60, 59}; // sort numbers in ascending order sort(std::begin(arr1), std::end(arr1)); // sort numbers in descending order sort(std::b...

C++ • Sorting

Ref and Out Parameters

The ref keyword is used to pass an Argument as Reference. out will do the same as ref but it does not require an assigned value by the caller prior to calling the function. Ref Parameter :-If you want to pass a variable as ref parameter then you need to initialize it before you pass it as ref param...

C# Language • Function with multiple return values

Custom data type with record parameters

Assume we want to create a data type Person, which has a first and last name, an age, a phone number, a street, a zip code and a town. We could write data Person = Person String String Int Int String String String If we want now to get the phone number, we need to make a function getPhone :: P...

Haskell Language • Creating Custom Data Types

Starting thinky in node.js

thinky is a lightweight node.js ORM for RethinkDB. First you need to have RethinkDB running on your server. Then install the thinky.io npm package into your project. npm install --save thinky Now import thinky into your model file. const thinky = require('thinky)(); const type = thinky.type ...

rethinkdb • using thinky.io with RethinkDB

Marshaling structs with private fields

As a good developer you have created following struct with both exported and unexported fields: type MyStruct struct { uuid string Name string } Example in Playground: https://play.golang.org/p/Zk94Il2ANZ Now you want to Marshal() this struct into valid JSON for storage in somet...

Go • JSON

Uninitialized variable

BAD CODE Dim f As System.Windows.Forms.Form f.ShowModal() GOOD CODE Dim f As System.Windows.Forms.Form = New System.Windows.Forms.Form ' Dim f As New System.Windows.Forms.Form ' alternative syntax f.ShowModal() EVEN BETTER CODE (Ensure proper disposal of IDisposable object more info) Us...

Visual Basic .NET Language • NullReferenceException

Getting binary representation of an image file

This example is inspired by this question. We'll assume you know how to load a file using the File API. // preliminary code to handle getting local file and finally printing to console // the results of our function ArrayBufferToBinary(). var file = // get handle to local file. var reader = new...

JavaScript • Binary Data

Searching For A Value In A Binary Search Tree With Recursion in C/C++

Structure for Binary Search Tree (BST) nodes: struct node { int data; node * left; node * right; } Search Algorithm // Check if a value exists in the tree bool BSTSearch(node * current, int value) { if (current->data == value) { return true; } e...

Recursion • Getting started with Recursion

Select dataset except where values are in this other dataset

--dataset schemas must be identical SELECT 'Data1' as 'Column' UNION ALL SELECT 'Data2' as 'Column' UNION ALL SELECT 'Data3' as 'Column' UNION ALL SELECT 'Data4' as 'Column' UNION ALL SELECT 'Data5' as 'Column' EXCEPT SELECT 'Data3' as 'Column' --Returns Data1, Data2, Data4, and Data5

SQL • EXCEPT

RLMObject Base Model Class with Primary Key - Objective-C

An example of a RLMObject base model class that uses a primary key and some generic default properties. Subclasses can then set metadata specific to their needs. @interface BaseModel : RLMObject @property NSString *uuid; @property NSString *metadata; @end @implementation BaseModel + (N...

iOS • Realm