C# movement code with the maximum movement speed.

Looks simple, but I can’t get it done for hours!Need help!

What kind of Player Movement are you looking for?
Here’s an example:

using UnityEngine;
using System.Collections;

public class PlayerController : MonoBehaviour {

	private Rigidbody2D m_Rigidbody;

	public float m_Speed ;
	public float m_JumpHeight ;
	public Transform groundCheck;
	public float groundCheckRadius;
	public LayerMask whatIsGround;
	private bool grounded;
	private bool  doubleJumped;

	// Use this for initialization
	void Start () {


		// Use this for initialization




		m_Rigidbody = GetComponent<Rigidbody2D>();

	}
	void FixedUpdate(){
		grounded = Physics2D.OverlapCircle (groundCheck.position, groundCheckRadius, whatIsGround);

	}

	// Update is called once per frame
	void Update () {



		if (grounded)
			doubleJumped = false;

		if (Input.GetKeyDown (KeyCode.Space)&& grounded) {
			m_Rigidbody.velocity = new Vector2 (m_Rigidbody.velocity.x, m_JumpHeight);
		}
		if (Input.GetKeyDown (KeyCode.Space) && !doubleJumped && !grounded) {

			m_Rigidbody.velocity = new Vector2 (m_Rigidbody.velocity.x, m_JumpHeight);
			doubleJumped = true;

		}
		if (Input.GetKey (KeyCode.D)) {

			m_Rigidbody.velocity = new Vector2 (m_Speed, m_Rigidbody.velocity.y);


		}
		if (Input.GetKey (KeyCode.A)) {
		m_Rigidbody.velocity = new Vector2 (-m_Speed, m_Rigidbody.velocity.y);

	}

}

}