Tutorial by Examples: l

Getting and setting elements

Use .get(key) to get value by key and .set(key, value) to assign a value to a key. If the element with the specified key doesn't exist in the map, .get() returns undefined. .set() method returns the map object, so you can chain .set() calls. const map = new Map(); console.log(map.get(1)); // und...

JavaScript • Map

Getting the number of elements of a Map

To get the numbers of elements of a Map, use the .size property: const map = new Map([[1, 2], [3, 4]]); console.log(map.size); // 2

JavaScript • Map

Setting state Added of a single entity

EntityState.Added can be set in two fully equivalent ways: By setting the state of its entry in the context: context.Entry(entity).State = EntityState.Added; By adding it to a DbSet of the context: context.Entities.Add(entity); When calling SaveChanges, the entity will be inse...

Entity Framework • Managing entity state

Remove unused alternative resources

All libraries come with resources that are not necessary useful to your application. For example Google Play Services comes with translations for languages your own application don’t even support. You can configure the build.gradle file to specify which resource you want to keep. For example: de...

android-gradle • Shrink Code and Resources

delegate

Delegates are types that represent a reference to a method. They are used for passing methods as arguments to other methods. Delegates can hold static methods, instance methods, anonymous methods, or lambda expressions. class DelegateExample { public void Run() { //using class ...

C# Language • Keywords

Linking projects for faster debugging and development

Building project dependencies can sometimes be a tedious task. Instead of publishing a package version to NPM and installing the dependency to test the changes, use npm link. npm link creates a symlink so the latest code can be tested in a local environment. This makes testing global tools and proje...

Node.js • npm

Locating comments

To locate comments in BeautifulSoup, use the text (or string in the recent versions) argument checking the type to be Comment: from bs4 import BeautifulSoup from bs4 import Comment data = """ <html> <body> <div> <!-- desired text --&gt...

beautifulsoup • Locating elements

The Other Looping Constructs: while and repeat

R provides two additional looping constructs, while and repeat, which are typically used in situations where the number of iterations required is indeterminate. The while loop The general form of a while loop is as follows, while (condition) { ## do something ## in loop body } whe...

R Language • Control flow structures

Reading/Writing Data Using System.IO.File

First, let's see three different ways of extracting data from a file. string fileText = File.ReadAllText(file); string[] fileLines = File.ReadAllLines(file); byte[] fileBytes = File.ReadAllBytes(file); On the first line, we read all the data in the file as a string. On the second line, we r...

.NET Framework • System.IO

Serial Ports using System.IO.SerialPorts

Iterating over connected serial ports using System.IO.Ports; string[] ports = SerialPort.GetPortNames(); for (int i = 0; i < ports.Length; i++) { Console.WriteLine(ports[i]); } Instantiating a System.IO.SerialPort object using System.IO.Ports; SerialPort port = new SerialPort(); ...

.NET Framework • System.IO

In-place replacement of a List element

This example is about replacing a List element while ensuring that the replacement element is at the same position as the element that is replaced. This can be done using these methods: set(int index, T type) int indexOf(T type) Consider an ArrayList containing the elements "Program sta...

Java Language • Lists

Conversion by explicit constructor or explicit conversion function

A conversion that involves calling an explicit constructor or conversion function can't be done implicitly. We can request that the conversion be done explicitly using static_cast. The meaning is the same as that of a direct initialization, except that the result is a temporary. class C { std:...

C++ • Explicit type conversions

Implicit conversion

static_cast can perform any implicit conversion. This use of static_cast can occasionally be useful, such as in the following examples: When passing arguments to an ellipsis, the "expected" argument type is not statically known, so no implicit conversion will occur. const double x = ...

C++ • Explicit type conversions

Override Equals and GetHashCode on custom types

For a class Person like: public class Person { public string Name { get; set; } public int Age { get; set; } public string Clothes { get; set; } } var person1 = new Person { Name = "Jon", Age = 20, Clothes = "some clothes" }; var person2 = new Person { Name ...

C# Language • Equals and GetHashCode

Equals and GetHashCode in IEqualityComparator

For given type Person: public class Person { public string Name { get; set; } public int Age { get; set; } public string Clothes { get; set; } } List<Person> persons = new List<Person> { new Person{ Name = "Jon", Age = 20, Clothes = "some clothes...

C# Language • Equals and GetHashCode

Rendering text along an arc.

This example shows how to render text along an arc. It includes how you can add functionality to the CanvasRenderingContext2D by extending its prototype. This examples is derived from the stackoverflow answer Circular Text. Example rendering Example code The example adds 3 new text renderi...

html5-canvas • Text

DML Triggers

DML Triggers are fired as a response to dml statements (insert, update or delete). A dml trigger can be created to address one or more dml events for a single table or view. This means that a single dml trigger can handle inserting, updating and deleting records from a specific table or view, but ...

Microsoft SQL Server • Trigger

Initializing object properties with null

All modern JavaScript JIT compilers trying to optimize code based on expected object structures. Some tip from mdn. Fortunately, the objects and properties are often "predictable", and in such cases their underlying structure can also be predictable. JITs can rely on this to make pred...

JavaScript • Performance Tips

Multiprocessing using built-in fork functions

You can use built-in functions to run PHP processes as forks. This is the most simple way to achieve parallel work if you don't need your threads to talk to each other. This allows you to put time intensive tasks (like uploading a file to another server or sending an email) to another thread so you...

PHP • Multiprocessing

[[fallthrough]]

C++17 Whenever a case is ended in a switch, the code of the next case will get executed. This last one can be prevented by using the ´break` statement. As this so-called fallthrough behavior can introduce bugs when not intended, several compilers and static analyzers give a warning on this. From ...

C++ • Attributes