File.OpenText() Method in C# with Examples

10 Nov, 2021
File.OpenText(String) is an inbuilt File class method which is used to open an existing UTF-8 encoded text file for reading.Syntax:  
public static System.IO.StreamReader OpenText (string path);
Parameter: This function accepts a parameter which is illustrated below:  
path: This is the specified text file which is going to be opened for reading.
Exceptions: 
UnauthorizedAccessException: The caller does not have the required permission.
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.
FileNotFoundException: The file specified in the path was not found.
NotSupportedException: The path is in an invalid format.
Return Value: Returns a StreamReader on the specified path.Below are the programs to illustrate the File.OpenText(String) method.Program 1: Before running the below code, a text file file.txt is created with some contents shown below-
Below code open the text file file.txt for reading.
C#
// C# program to illustrate the usage// of File.OpenText(String) method // Using System and System.IO// namespacesusing System;using System.IO; class Test {    public static void Main()    {        // Specifying a text file        string path = @"file.txt";         // Opening the file for reading        using(StreamReader sr = File.OpenText(path))        {            string s = "";            while ((s = sr.ReadLine()) != null) {                // printing the file contents                Console.WriteLine(s);            }        }    }}
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.OpenText(String) method // Using System and System.IO// namespacesusing System;using System.IO; class Test {    public static void Main()    {        // Specifying a text file        string path = @"file.txt";         // Checking the existence of file        if (File.Exists(path)) {            using(StreamWriter sw = File.CreateText(path))            {                // Overwriting the file with below                // specified contents                sw.WriteLine("GFG is a CS portal.");            }        }         // Opening the file for reading        using(StreamReader sr = File.OpenText(path))        {            string s = "";            while ((s = sr.ReadLine()) != null) {                // printing the overwritten content                Console.WriteLine(s);            }        }    }}
Executing: 
GFG is a CS portal.
arorakashish0911
clintra
CSharp-File-Handling
C#
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