Get File Extension in C#

Introduction

The Extension property of the FileInfo class returns the extension of a file. The following code snippet returns the extension of a file.

C# Get File Extension

string extn = fi.Extension;
Console.WriteLine("File Extension: {0}", extn);

Example

Here is a complete code example. Don't forget to import System.IO and System.Text namespaces in your project. The following code example uses a FileInfo class to create an object by passing a complete filename. The FileInfo class provides properties to get information about a file, such as file name, size, full path, extension, and directory name, and is read-only when the file was created and last updated.

// Full file name. Change your file name
string fileName = @"/Users/praveen/Desktop/images/November.pdf";
FileInfo fi = new FileInfo(fileName);

// Get File Name
string justFileName = fi.Name;
Console.WriteLine("File Name: {0}", justFileName);

// Get file name with full path
string fullFileName = fi.FullName;
Console.WriteLine("File Name: {0}", fullFileName);

// Get file extension
string extn = fi.Extension;
Console.WriteLine("File Extension: {0}", extn);

// Get directory name
string directoryName = fi.DirectoryName;
Console.WriteLine("Directory Name: {0}", directoryName);

// File Exists ?
bool exists = fi.Exists;
Console.WriteLine("File Exists: {0}", exists);

if (fi.Exists)
{
    // Get file size
    long size = fi.Length;
    Console.WriteLine("File Size in Bytes: {0}", size);

    // File ReadOnly ?
    bool IsReadOnly = fi.IsReadOnly;
    Console.WriteLine("Is ReadOnly: {0}", IsReadOnly);

    // Creation, last access, and last write time
    DateTime creationTime = fi.CreationTime;
    Console.WriteLine("Creation time: {0}", creationTime);

    DateTime accessTime = fi.LastAccessTime;
    Console.WriteLine("Last access time: {0}", accessTime);

    DateTime updatedTime = fi.LastWriteTime;
    Console.WriteLine("Last write time: {0}", updatedTime);
}

The output looks like the following, where you can see the file extension is displayed.

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