How do you read a file asynchronously in C#?

Question

ICSM Computer · Answer

In C#, you can read a file asynchronously using methods like 
File.ReadAllTextAsync, File.ReadAllLinesAsync, or by using 
StreamReader.ReadLineAsync() in an async loop. Asynchronous file I/O is useful for keeping your app responsive, especially in UI or web apps.
Example 1: Read the entire file as a string
using System;
using System.IO;
using System.Threading.Tasks;
class Program
{
    static async Task Main()
    {
        string filePath = @"C:\example.txt";
        try
        {
            string content = await File.ReadAllTextAsync(filePath);
            Console.WriteLine(content);
        }
        catch (Exception ex)
        {
            Console.WriteLine("Error: " + ex.Message);
        }
    }
}
Example 2: Read file line-by-line asynchronously
using System;
using System.IO;
using System.Threading.Tasks;
class Program
{
    static async Task Main()
    {
        string filePath = @"C:\example.txt";
        try
        {
            using (StreamReader reader = new StreamReader(filePath))
            {
                string? line;
                while ((line = await reader.ReadLineAsync()) != null)
                {
                    Console.WriteLine(line);
                }
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine("Error: " + ex.Message);
        }
    }
}
Other async file reading methods:
File.ReadAllLinesAsync(path) – returns a string[]File.ReadBytesAsync(path) – returns a byte[] (for binary files)

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How do you read a file asynchronously in C#?

ICSM Computer

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1 Answers

Example 1: Read the entire file as a string

Example 2: Read file line-by-line asynchronously

Other async file reading methods:

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