How to read from a text file (C# Programming Guide)

 https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/file-system/how-to-read-from-a-text-file

This example reads the contents of a text file by using the static methods ReadAllText and ReadAllLines from the System.IO.File class.

For an example that uses StreamReader, see How to read a text file one line at a time.

 Note

The files that are used in this example are created in the topic How to write to a text file.

Example

C#

class ReadFromFile
{
    static void Main()
    {
        // The files used in this example are created in the topic
        // How to: Write to a Text File. You can change the path and
        // file name to substitute text files of your own.

        // Example #1
        // Read the file as one string.
        string text = System.IO.File.ReadAllText(@"C:\Users\Public\TestFolder\WriteText.txt");

        // Display the file contents to the console. Variable text is a string.
        System.Console.WriteLine("Contents of WriteText.txt = {0}", text);

        // Example #2
        // Read each line of the file into a string array. Each element
        // of the array is one line of the file.
        string[] lines = System.IO.File.ReadAllLines(@"C:\Users\Public\TestFolder\WriteLines2.txt");

        // Display the file contents by using a foreach loop.
        System.Console.WriteLine("Contents of WriteLines2.txt = ");
        foreach (string line in lines)
        {
            // Use a tab to indent each line of the file.
            Console.WriteLine("\t" + line);
        }

        // Keep the console window open in debug mode.
        Console.WriteLine("Press any key to exit.");
        System.Console.ReadKey();
    }
}

Compiling the Code

Copy the code and paste it into a C# console application.

If you are not using the text files from How to write to a text file, replace the argument to ReadAllText and ReadAllLines with the appropriate path and file name on your computer.

Robust Programming

The following conditions may cause an exception:

• The file doesn't exist or doesn't exist at the specified location. Check the path and the spelling of the file name.

.NET Security

Do not rely on the name of a file to determine the contents of the file. For example, the file myFile.cs might not be a C# source file.

See also

• System.IO
• C# Programming Guide
• File System and the Registry (C# Programming Guide)