Path.GetFileNameWithoutExtension(string)

Description

Returns the file base component of the specified path string without the extension.

The return value consists of the string returned by GetFileName(), minus the extension separator character and extension.

//Remember to import IO to make Path work.
import System.IO;

function Start () {
    //This will print "foo".
    Debug.Log(Path.GetFileNameWithoutExtension("/Some/File/At/foo.extension"));
}

using System.IO;
using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    void Start() {
        Debug.Log(Path.GetFileNameWithoutExtension("/Some/File/At/foo.extension"));
    }
}