OnTriggerExit Coroutine won't stop?

Question

i use StopCoroutine to stop "AttackPlayer", but their keep exculte the TakeDamage() function, even i stop it.

how to totally stop the IEnumerator , use bool to turn the whileloop on and off?

   void OnTriggerEnter(Collider other)
    {
        if (other.TryGetComponent(out Player player))
        {
            // Attack the player
            StartCoroutine(AttackPlayer(other));
        }
    }

   void OnTriggerExit(Collider other)
    {
        if (other.TryGetComponent(out Player player))
        {
            // Stop attacking the player
            StopCoroutine("AttackPlayer");
        }
    }

    IEnumerator AttackPlayer(Collider playerCollider)
    {
        Player player = playerCollider.GetComponent<Player>();
        while (player != null)
        {
              TakeDamage();
              yield return new WaitForSeconds(AttackSpeed);
        }
    }

Answer 1

S. Tank Çetin's answer correctly shows why your code doesn't work. What you can do instead is capture a reference to the coroutine in progress when you start it, then stop that:

Coroutine _attackInProgress;

void OnTriggerEnter(Collider other)
{
    if (_attackInProgress == null && other.TryGetComponent(out Player player))
    {
        // Attack the player
        _attackInProgress = StartCoroutine(AttackPlayer(player));
    }
}

void OnTriggerExit(Collider other)
{
    if (_attqckInProgress != null && other.TryGetComponent(out Player player))
    {
        // Stop attacking the player
        StopCoroutine(_attackInProgress);
        _attackInProgess = null;
    }
}

IEnumerator AttackPlayer(Player player)
{
    while (player != null)
    {
          TakeDamage();
          yield return new WaitForSeconds(AttackSpeed);
    }

    _attackInProgress = null;
}

You'll notice I (again) changed your AttackPlayer function to accept a Player, not a Collider. It's unnecessarily wasteful to search for the Player component twice, once in OnTriggerEnter and again in AttackPlayer, when the calling function could have just given it an instance of the type it needs directly.

Answer 2

You can't start with the function call syntax and end with the string syntax.

Note: Do not mix the three arguments. If a string is used as the argument in StartCoroutine, use the string in StopCoroutine. Similarly, use the IEnumerator in both StartCoroutine and StopCoroutine. Finally, use StopCoroutine with the Coroutine used for creation.

See here: https://docs.unity3d.com/ScriptReference/MonoBehaviour.StopCoroutine.html