File.ReadLines(String) Method in C# with Examples
File.ReadLines(String) is an inbuilt File class method that is used to read the lines of a file.
Syntax:
public static System.Collections.Generic.IEnumerable ReadLines (string path);
Parameter: This function accepts a parameter which is illustrated below:
- path: This is the specified file for reading.
Exceptions:
- ArgumentException: The path is a zero-length string, contains only white space, or one or more invalid characters defined by the GetInvalidPathChars() method.
- ArgumentNullException: The path is null.
- DirectoryNotFoundException: The path is invalid.
- FileNotFoundException: The file specified by the path was not found.
- IOException: An I/O error occurred while opening the file.
- PathTooLongException: The path exceeds the system-defined maximum length.
- SecurityException: The caller does not have the required permission.
- UnauthorizedAccessException: The path specifies a file that is read-only. OR this operation is not supported on the current platform. OR the path is a directory. OR the caller does not have the required permission.
Return Value: Returns all the lines of the specified file.
Below are the programs to illustrate the File.ReadLines(String) method.
Program 1: Initially, a file file.txt is created with some contents shown below-
// C# program to illustrate the usage // of File.ReadLines(String) method // Using System and System.IO namespaces using System; using System.IO; public class GFG { public static void Main(String[] argv) { // Calling the ReadLines(String) function foreach ( string line in File.ReadLines( @"file.txt" )) { // Printing the file contents Console.WriteLine(line); } } } |
Output:
GFG gfg Beginner w3wiki w3wiki
Program 2: Initially, a file file.txt is created with some contents shown below-
Below code filter some contents from the file and prints them back.
// C# program to illustrate the usage // of File.ReadLines(String) method // Using System and System.IO namespaces using System; using System.IO; public class GFG { public static void Main(String[] argv) { // Calling the ReadLines(String) function foreach ( string line in File.ReadLines( @"file.txt" )) { // Filtering the file contents and printing if (line.Contains( "GFG" )) { Console.WriteLine(line); } } } } |
Output:
GFG