How to do something if two keys are pressed at the same time in a specific order?

Hi, so I am making an fps game, and i made animations for walking in 4 directions: walking forward, walking backwards, walking left and walking right, i am using the animator but my “problem” is that when i am pressing “a” (is playing the “walking left” animation), and then i press “d” (while pressing a), it plays the animation to go to the right, but i want it to keep playing the “walking left” animation until i release the “a” key so the character can finally play the “walking right” animation. My code is this one.

public class FPSController : MonoBehaviour {
	static Animator anim;
	// Use this for initialization
	void Start () {
		anim = GetComponent<Animator> ();
		anim.SetInteger ("isWalking", 0);
	}
	
	// Update is called once per frame
	void Update () {
		bool isForward;
		bool isBack;
		bool isLeft;
		bool isRight;

		isForward = Input.GetKeyDown ("w");
		isBack = Input.GetKeyDown ("s");
		isLeft = Input.GetKeyDown ("a");
		isRight = Input.GetKeyDown ("d");

		if (isForward == true) {
			anim.SetFloat("Speed", 0.0f);
			anim.SetInteger ("isWalking", 1);
		}
		if (isBack == true) {
			anim.SetFloat("Speed", 0.5f);
			anim.SetInteger ("isWalking", 1);
		}
		if (isLeft == true) {
			anim.SetFloat("Speed", 1.0f);
			anim.SetInteger ("isWalking", 1);
		}
		if (isRight == true) {
			anim.SetFloat("Speed", 1.5f);
			anim.SetInteger ("isWalking", 1);
		}
		if(Input.anyKey == false){
			anim.SetInteger ("isWalking", 0);
		}

		if (Input.GetButtonDown ("Fire2")) {
			anim.SetBool ("isAiming", true);
		} 
		if (Input.GetButtonUp ("Fire2")) {
			anim.SetBool ("isAiming", false);
		} 
		if (Input.GetKeyDown (KeyCode.LeftShift)) {
			anim.SetInteger ("isWalking", 2);
		}
		if (Input.GetKeyUp (KeyCode.LeftShift)) {
			anim.SetInteger ("isWalking", 1);
		}
	}

}

I am using the default controller for the movement itself (the one that comes in the standard assets).
In advance, thank you, if someone can help me.

Handle Your State in the Actual (Animator) State Machine Instead!

I think the first and most important problem here is that you’re handling all your states in that script itself instead of in the animator controller, which is already a state machine designed for that exact purpose!

In the animator you can setup many different conditions to control exactly what, when and how animations play. It’s a huge topic though, so I would recommend you go study up on the Animator controller more.

As for the code itself, the D key overrides the A key simply because your checking isRight after checking isLeft. Changing the order of these if conditions will change the priority. However, then you just have the oppiste problem of A overriding D, So it would be best to just add an additional check to each if statement, like this:

         if (isRight == true && isLeft == false) {
             anim.SetFloat("Speed", 1.5f);
             anim.SetInteger ("isWalking", 1);
         }

But all these conditions should actually be controlled in the animator controller itself.