What does $ in c# mean?

The $ symbol in C# has the following three main meanings: 1. String interpolation, used to embed expressions in strings; 2. Anonymous types, used to create temporary types whose properties and initializers Corresponding to the expressions in; 3. Pattern matching, used to match different expression patterns and specify operations.

$

in C# In C#, the $ symbol has the following meaning:

String Interpolation

#$ notation is used for string interpolation, allowing expressions to be embedded directly in a string. This allows us to easily insert variables, constants, and complex expressions into strings.

Syntax:

<code class="c#">$"字符串 {变量} 表达式"</code>

For example:

<code class="c#">int age = 25;
string message = $"我的年龄是 {age}。";</code>

Anonymous type

$ The symbol is also used for anonymous type. It allows us to create an unnamed temporary type whose properties correspond to the expression in the initializer.

Syntax:

<code class="c#">new { 属性名 = 值, ... }</code>

For example:

<code class="c#">var person = new { Name = "Alice", Age = 25 };</code>

Pattern matching

In C# 9.0, $ Symbols are used for pattern matching. It allows us to match different expression patterns and specify different actions for each pattern.

Syntax:

<code class="c#">expression switch
{
    pattern1 => expression1,
    pattern2 => expression2,
    ...
}</code>

For example:

<code class="c#">switch (age)
{
    case 18..25:
        Console.WriteLine("年轻人");
        break;
    case 26..60:
        Console.WriteLine("中年人");
        break;
    default:
        Console.WriteLine("老年人");
        break;
}</code>

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