Tutorial by Examples: co

Angles are in Radians, not Degrees. All computations are done in IEEE 754 64-bit floating point. All floating point computations are subject to small errors, known as machine ε (epsilon) errors, so avoid trying to compare them for equality. There is no way to avoid these errors when using floating p...

public class ConnectSocketExample { private int HTTP_PORT = 80; /** * example method to create unconnected socket * then connect to it * at end return connected socket * * @param httpHostName - endpoint host name fot socket connection * @throws IOEx...

import java.util.Scanner; Scanner s = new Scanner(System.in); int number = s.nextInt(); If you want to read an int from the command line, just use this snippet. First of all, you have to create a Scanner object, that listens to System.in, which is by default the Command Line, when you start ...

Mapping Applying a function to all elements of an array : array_map('strtoupper', $array); Be aware that this is the only method of the list where the callback comes first. Reducing (or folding) Reducing an array to a single value : $sum = array_reduce($numbers, function ($carry, $number) { ...

WebSocket provides a duplex/bidirectional communication protocol over a single TCP connection. the client opens a connection to a server that is listening for a WebSocket request a client connects to a server using a URI. A server may listen to requests from multiple clients. Server Endpoint...

The easiest and quickest way to encode a Haskell data type to JSON with Aeson is using generics. {-# LANGUAGE DeriveGeneric #-} import GHC.Generics import Data.Text import Data.Aeson import Data.ByteString.Lazy First let us create a data type Person: data Person = Person { firstName :...

You should not save props into state. It is considered an anti-pattern. For example: export default class MyComponent extends React.Component { constructor() { super(); this.state = { url: '' } this.onChange = this.onChange.bind(this); ...

If you want to extract something from a webpage (or any representation/programming language), a regex is the wrong tool for the task. You should instead use your language's libraries to achieve the task. If you want to read HTML, or XML, or JSON, just use the library that parses it properly and ser...

By using the .HasKey() method, a set of properties can be explicitly configured as the composite primary key of the entity. using System.Data.Entity; // .. public class PersonContext : DbContext { // .. protected override void OnModelCreating(DbModelBuilder modelBuilder) {...

Since workers run in a separate thread from the one that created them, communication needs to happen via postMessage. Note: Because of the different export prefixes, some browsers have webkitPostMessage instead of postMessage. You should override postMessage to make sure workers "work" (n...

XSD schema (schema.xsd) The following xml schema (xsd) defines a list of users with attributes name and reputation. <?xml version="1.0"?> <xs:schema version="1.0" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:ns="http://www...

The markdown help states Available conditionals are gt, gte, lt, lte, eq, and neq. <!-- if version [eq C++03] --> eq equal to <!-- end version if --> <!-- if version [neq C++03] --> neq not equal to <!-- end version if --> <!-- if version [gt C++03] -...

Multiple conditions can be used. <!-- if version [lte 1.2.0] [gt 1.3.12] [gt 1.4.9] [neq 1.2.0] [eq 1.5.7] --> content <!-- end version if -->

SELECT s.name AS [schema], t.object_id AS [table_object_id], t.name AS [table_name], c.column_id, c.name AS [column_name], i.name AS [index_name], i.type_desc AS [index_type] FROM sys.schemas AS s INNER JOIN sys.tables AS t ON s.schema_id = t.schema_id I...

One might want to GROUP BY more than one column declare @temp table(age int, name varchar(15)) insert into @temp select 18, 'matt' union all select 21, 'matt' union all select 21, 'matt' union all select 18, 'luke' union all select 18, 'luke' union all select 21, 'luke' union all select 1...

-- Identity primary key - unique arbitrary increment number create table person ( id int identity(1,1) primary key not null, firstName varchar(100) not null, lastName varchar(100) not null, dob DateTime not null, ssn varchar(9) not null )

-- composite key - using two or more existing columns within a table to create a primary key create table person ( firstName varchar(100) not null, lastName varchar(100) not null, dob DateTime not null, ssn varchar(9) not null, primary key (firstName, lastName, dob) )

AssemblyConfiguration: The AssemblyConfiguration attribute must have the configuration that was used to build the assembly. Use conditional compilation to properly include different assembly configurations. Use the block similar to the example below. Add as many different configurations as you com...

The using keyword ensures that the resource defined within the statement only exists within the scope of the statement itself. Any resources defined within the statement must implement the IDisposable interface. These are incredibly important when dealing with any connections that implement the IDi...

In addition to break, there is also the keyword continue. Instead of breaking completely the loop, it will simply skip the current iteration. It could be useful if you don't want some code to be executed if a particular value is set. Here's a simple example: for (int i = 1; i <= 10; i++) { ...