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event

An event allows the developer to implement a notification pattern. Simple example public class Server { // defines the event public event EventHandler DataChangeEvent; void RaiseEvent() { var ev = DataChangeEvent; if(ev != null) { ev(t...

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 %timeit and `%time` magics

The %timeit magic runs the given code many times, then returns the speed of the fastest result. In [1]: %timeit sum(range(100000)) 100 loops, best of 3: 2.91 ms per loop The %%timeit cell magic can be used to time blocks of code. In [2]: %%timeit ...: a = 0 ...: for i in range(100000):...

ipython • Magics

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

Exact Numerics

There are two basic classes of exact numeric data types - Integer, and Fixed Precision and Scale. Integer Data Types bit tinyint smallint int bigint Integers are numeric values that never contain a fractional portion, and always use a fixed amount of storage. The range and storage sizes o...