File.OpenRead() Method in C# with Examples Last Updated : 28 Apr, 2025 Comments Improve Suggest changes Like Article Like Report File.OpenRead(String) is an inbuilt File class method which is used to open an existing file for reading.Syntax: public static System.IO.FileStream OpenRead (string path); Parameter: This function accepts a parameter which is illustrated below: path: This is the specified file which is going to be opened for reading. Exceptions: ArgumentException: The path is a zero-length string, contains only white space, or one or more invalid characters as defined by InvalidPathChars.ArgumentNullException: The path is null.PathTooLongException: The specified path, file name, or both exceed the system-defined maximum length.DirectoryNotFoundException: The specified path is invalid.UnauthorizedAccessException: The path specified a directory. OR the caller does not have the required permission.FileNotFoundException: The file specified in the path was not found.NotSupportedException: The path is in an invalid format.IOException: An I/O error occurred while opening the file. Return Value: Returns a read-only FileStream on the specified path.Below are the programs to illustrate the File.OpenRead(String) method.Program 1: Before running the below code, a file file.txt is created with some contents shown below Below code open the file file.txt for reading. C# // C# program to illustrate the usage // of File.OpenRead(String) method // Using System, System.IO and // System.Text namespaces using System; using System.IO; using System.Text; class Test { public static void Main() { // Specifying a file string path = @"file.txt"; // Opening the existing file for reading using(FileStream fs = File.OpenRead(path)) { byte[] b = new byte[1024]; UTF8Encoding temp = new UTF8Encoding(true); while (fs.Read(b, 0, b.Length) > 0) { // Printing the file contents Console.WriteLine(temp.GetString(b)); } } } } Executing: GeeksforGeeks Program 2: Initially, a file file.txt is created with some contents shown below- This below code will overwrite the file contents with other specified contents then final contents will be printed. C# // C# program to illustrate the usage // of File.OpenRead(String) method // Using System, System.IO and // System.Text namespaces using System; using System.IO; using System.Text; class GFG { public static void Main() { // Specifying a file string path = @"file.txt"; // Opening the file for overwriting with // another contents using(FileStream fs = File.OpenWrite(path)) { Byte[] info = new UTF8Encoding(true).GetBytes("GFG is a CS portal."); fs.Write(info, 0, info.Length); } // Opening the existing file for reading using(FileStream fs = File.OpenRead(path)) { byte[] b = new byte[1024]; UTF8Encoding temp = new UTF8Encoding(true); while (fs.Read(b, 0, b.Length) > 0) { // Printing the file contents Console.WriteLine(temp.GetString(b)); } } } } Executing: GFG is a CS portal. Comment More infoAdvertise with us Next Article File.Move() Method in C# with Examples K Kanchan_Ray Follow Improve Article Tags : C# CSharp-File-Handling Similar Reads File.OpenWrite() Method in C# with Examples File.OpenWrite(String) is an inbuilt File class method that is used to open an existing file or creates a new file for writing. 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