EN CSharp Keyword as

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C#: as

Handbook C# · Practical Guide

Attempts to convert a reference or nullable value; returns null if the conversion does not fit.

Simple example (Example.cs)

Save this example separately as Example.cs. Run it independently of the other examples on this page.

Example.cs:

// PROJECT-EXAMPLE
object value = "ore";
string? text = value as string;
System.Console.WriteLine(text ?? "Missing");

Result:

ore

Syntax

value as Type

Example 1: simple form

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using System.IO;
using System.Runtime.InteropServices;
using System.Runtime.CompilerServices;

public static class Program
{
    public static async Task Main(string[] args)
    {
        object value = "ore";
        string? text = value as string;
        Console.WriteLine(text ?? "Missing");
    }
}

Example 2: another practical form

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using System.IO;
using System.Runtime.InteropServices;
using System.Runtime.CompilerServices;

public static class Program
{
    public static async Task Main(string[] args)
    {
        object value = 12;
        int? number = value as int?;
        Console.WriteLine(number.GetValueOrDefault());
    }
}

Official source: Microsoft Learn.