Tutorial by Examples: r

Parameters can be marked as optional by giving them a default value. Optional parameters can be omitted when calling the function. string greet (string name, string language = "English") { if (language == "English") { return @"Hello, $name!"; } else ...

Value types (structures and enumerations) are passed by value to functions: a copy will be given to the function, not a reference to the variable. So the following function won't do anything. void add_three (int x) { x += 3; } int a = 39; add_three (a); assert (a == 39); // a is still 39...

You can assert that parameters have certain values with requires. int fib (int i) requires (i > 0) { if (i == 1) { return i; } else { return fib (i - 1) + fib (i - 2); } } fib (-1); You won't get any error during the compilation, but you'll get an error wh...

int sum (int x, ...) { int result = x; va_list list = va_list (); for (int? y = list.arg<int?> (); y != null; y = list.arg<int?> ()) { result += y; } return result; } int a = sum (1, 2, 3, 36); With this function, you can pass as many int as you w...

A key part of the Reader monad is the ask (https://hackage.haskell.org/package/mtl-2.2.1/docs/Control-Monad-Reader.html#v:ask) function, which is defined for illustrative purposes: import Control.Monad.Trans.Reader hiding (ask) import Control.Monad.Trans ask :: Monad m => ReaderT r m r ask ...

This is an official MATLAB example Consider the following code: month = [1;1;2;3;8;1;3;4;9;11;9;12;3;4;11]; temperature = [57;61;60;62;45;59;64;66;40;56;38;65;61;64;55]; maxTemp = accumarray(month,temperature,[],@max); The image below demonstrates the computation process done by accumarray in...

A discriminant of a record type may influence the structure of objects. A choice of components may exists in an object according as a discriminant had had a particular value when the object was created. To support this variation, a record type's definition includes a distinction by cases that depend...

Generic subprograms are usefull to create a subprograms that have the same structure for several types. For example, to swap two objects: generic type A_Type is private; procedure Swap (Left, Right : in out A_Type) is Temp : A_Type := Left; begin Left := Right; Right := Temp; ...

In Ada generic package, upon instantiation, data are duplicated; that is, if they contain global variables, each instance will have its own copy of the variable, properly typed and independent from the others. generic type T is private; package Gen is type C is tagged record V :...

Ada offers a wide variety of generic parameters which is difficult to translate into other languages. The parameters used during instantiation and as a consequence those on which the generic unit may rely on may be variables, types, subprograms, or package instances, with certain properties. For exa...

These exceptions are caused when the type of some object should be different TypeError: [definition/method] takes ? positional arguments but ? was given A function or method was called with more (or less) arguments than the ones it can accept. Example If more arguments are given: def foo(a): re...

Let's see all the basic component for create a simple Hallo World. Define which implementation of JPA 2.1 we will use Build the connection to database creating the persistence-unit Implements the entities Implements DAO (Data access object) for manipulate the entities Test the application ...

Getting elements to center or bottom align vertically has always been a challenge with CSS and Bootstrap. The desired vertical alignment may be within a parent container, or relative to adjacent elements. Now that Bootstrap 4 is flexbox by default there are many different approaches to vertical ali...

It's similar to Vue.js version 1, version 2 can be directly embedded in a single html file. To include Vue.js2 in html file, make sure you have the script file included in the HTML. For example, use the following HTML. It should display the Hello message correctly. <div id="app">{...

This example shows a simple but effective splash screen with animation that can be created by using Android Studio. Step 1: Create an animation Create a new directory named anim in the res directory. Right-click it and create a new Animation Resource file named fade_in.xml: Then, put the follow...

An example project (Git repo) that can be used as a starting point for doing some 3D rendering. The code for setting up OpenGL and the shaders is quite long and tedious so it wont fit well under this example format. Later pieces of it can be shown in separate examples detailing what exactly is going...

You can see the running demo by clicking here. HTML: <p> <span>Counter State</span><br /> (<em>Will increase each minute</em>): <p> <span id="counter-state" style="font-weight: bolder"></span> </p> &l...

Active Record Transactions can be applied to Model classes as well as Model instances, the objects within the transaction block need not all be instances of same class. This is because transactions are per-database connection, not per-model. For example: User.transaction do account.save! prof...

To flatten multidimensional array into single dimension, flatMap advance functions is used. Other use case is to neglect nil value from array & mapping values. Let's check with example:- Suppose We have an multidimensional array of cities & we want to sorted city name list in ascending orde...

Using Oracle SQL’s NVL2() function, you can create a display column which contains one value if a field contains data and another value if a field does not contain data. For example, in an Entity search, turn the presence of a primary e-mail address into a text display column: NVL2( {email} , 'YES...