Some sound Script Error

Unity Engine
1

Hello to everyone I take script from this question: Footstep sounds when walking - Questions & Answers - Unity Discussions and modify it a little but in the part of Script audio.clip = concreteSound[Random.Range(0, concreteSound.Lenght)]; the “Length” make an Error does not contain a definition. Can some one please help me to fix it.

Here is the full Script:

public class footStepSoundControll : MonoBehaviour {
    public CharacterController controller;
    public AudioClip concreteSound;
    private bool step = true;
    float audioStepLengthWalk = 0.45f;
    // Use this for initialization
    void Start () {
        controller = GetComponent<CharacterController>();
    }
    void OnControllerColliderHit (ControllerColliderHit hit)
    {
        //Debug.Log("Controller hit the ground");
        if (controller.isGrounded && controller.velocity.magnitude < 7 && controller.velocity.magnitude > 5 && hit.gameObject.tag == "Untagged" && step == true )
        {
            WalkOnConcrete();
        }
    }
    IEnumerator WaitForFootSteps(float stepsLength)
    {
        step = false;
        yield return new WaitForSeconds(stepsLength);
        step = true;
    }
    public void WalkOnConcrete ()
    {
        audio.clip = concreteSound[Random.Range(0, concreteSound.Lenght)];
        audio.volume = 0.1f;
        audio.Play();
        StartCoroutine(WaitForFootSteps(audioStepLengthWalk));
    }
   
}
2

Alsow if use script like this it plays sound but only onese when button is pressed, and ones when button is Up

public void WalkOnConcrete ()
    {
        audio.clip = concreteSound; //[Random.Range(0, concreteSound.Lenght)];
        audio.volume = 1f;
        audio.Play();
        StartCoroutine(WaitForFootSteps(audioStepLengthWalk));
    }
3

In your first post your script has a typo at line 26 (Lenght instead of Length).

4

I fixed it thing is thats not the reason of error, i forgot to input an array in AudioClip part [ ] , now I fixed it and the problem gone, but sound still play only once when walking insted of looping.