Sprinting problem

hello unity forms, this is my first post and i am new to unity
i have been trying to learn unity and i have done a little progress. i made a charecter controller with brackyes code on fps controller and i tried implimenting new functions to it like sprinting crouching etc however i tried to add sprinting with a fov effect (with GD,tweening) and eveything is fine that only thing is that i want it to only work when it its grounded , kind of like toggling to sprint, here is how i would like it to work:-
when that charecter is grounded and pressing w he can sprint and jump wile sprinting BUT
if that character is in mid air he cannot start sprinting.here are my codes

using UnityEngine;



public class player_movement_script : MonoBehaviour
{
    public CharacterController controller;
    public float speed = 10f;
    public float SprintSpeed = 15f;
    public float gravity = -30f;
    public float jumpheight = 3f;
    public Transform groundCheck;
    public float groundDistance = 0.4f;
    public LayerMask groundMask;
    public mouse_control Cam;

    public Vector3 velocity;
    bool isGrounded;
  

    // Update is called once per frame
    void Update()
    {
        isGrounded = controller.isGrounded;

        if (isGrounded && velocity.y < 0){
            velocity.y = -2f;
        }


        float player_positionX = Input.GetAxis("Horizontal");
        float player_positionY = Input.GetAxis("Vertical");

        Vector3 move = transform.right * player_positionX + transform.forward * player_positionY;
        //default
      
        Cam.DoFOV(60);

        if (Input.GetKey(KeyCode.LeftShift) && Input.GetKey(KeyCode.W))
        {
            controller.Move(move * SprintSpeed * Time.deltaTime);
            Cam.DoFOV(80);

        }
        else
        {
            controller.Move(move * speed * Time.deltaTime);
            Cam.DoFOV(60);
        }

      
        if (!isGrounded){
            velocity.y += gravity * Time.deltaTime;
        }

        if (Input.GetButtonDown("Jump") && isGrounded)
        {
            velocity.y = Mathf.Sqrt(jumpheight * -2f * gravity);
        }
      

        controller.Move(velocity * Time.deltaTime);
    }


}

note(fov funtion is referenced to a script in main camera)

please help me i am stuck and i serched everywhere for help

Well you have already shown how to detect if the player is on the ground with this section of code:

if (!isGrounded)
{
    velocity.y += gravity * Time.deltaTime;
}

if (Input.GetButtonDown("Jump") && isGrounded)
{
    velocity.y = Mathf.Sqrt(jumpheight * -2f * gravity);
}

So you merely need to apply to apply the same principle and check if the player is grounded in same if condition for jumping. Hell you could make it nice and readable like so:

Vector3 direction = move * Time.deltaTime;

bool sprintIsPressed = Input.GetKey(KeyCode.LeftShift);
bool wIsPressed = Input.GetKey(KeyCode.W);

bool canSprint == sprintIsPressed && wIsPressed && isGrounded;

if (canSprint)
{
    move *= SprintSpeed;   
    Cam.DoFOV(80);
}
else
{
    Cam.DoFOV(60);
}

controller.Move(direction);

Hopefully this gives you some ideas.

yes and inneed i have tried adding is grounded in the sprint condition

into

if (Input.GetKey(KeyCode.LeftShift) && Input.GetKey(KeyCode.W) && && isGrounde)
        {
            controller.Move(move * SprintSpeed * Time.deltaTime);
            Cam.DoFOV(80);
        }

and this causes the player to stop sprinting when it is on the air, and when it lands it gets back to sprinting.

i want the player to be able to sprint when it starts sprinting for the ground(doesn’t matter if it jumps)
the only condidtion i want is that the player cannont start sprinting in mid air

Then you just want to maintain some form of state. You could easily have a private bool isSprinting; that you flip to true only if the right condition is met (Shift + W + isGrounded). You can flip it back to false probably when the player isn’t inputting Shift or W any longer.

Then later on, if isSprinting is true, you add a little extra onto the direction to move in before you supply it to controller.Move.

as i am beginner in in unity and in c sharp(i am not new in programming but in c sharp) it would be quite helpful if you could show me how to do that toggleing the sprint functing thing; nevertheless i have implimented a toggle function in past with bool values and didn’t changed anything but still help will be appriciated

// Toggle the boolean variable using the logical NOT operator
isToggled = !isToggled;

See where isGrounded is declared now see where isSprinting is declared. If you want state of isSprinting to persist between calls you need to move it outside of function. Variables declared within functions are wiped when function exits (there are gotchas, but that’s not beginner level details)

can please anyone can re write the code for me, i am working on my dream game and i am afraid that i will ruin it because i am very new to unity and priviously i messed with unity and runined my project, two times .
this time i am looking forward for help from professionals

You started working on your dream game without first taking the time to master the engine/software you’re going to be using? That is not a recipe for success!

No, you need to change your learning strategy. Try this one: ask yourself “Can I … ?” again and again.

Imphenzia: How Did I Learn To Make Games:

https://www.youtube.com/watch?v=b3DOnigmLBY

Tutorials and example code are great, but keep this in mind to maximize your success and minimize your frustration:

How to do tutorials properly, two (2) simple steps to success:

Step 1. Follow the tutorial and do every single step of the tutorial 100% precisely the way it is shown. Even the slightest deviation (even a single character!) generally ends in disaster. That’s how software engineering works. Every step must be taken, every single letter must be spelled, capitalized, punctuated and spaced (or not spaced) properly, literally NOTHING can be omitted or skipped.
Fortunately this is the easiest part to get right: Be a robot. Don’t make any mistakes.
BE PERFECT IN EVERYTHING YOU DO HERE!!

If you get any errors, learn how to read the error code and fix your error. Google is your friend here. Do NOT continue until you fix your error. Your error will probably be somewhere near the parenthesis numbers (line and character position) in the file. It is almost CERTAINLY your typo causing the error, so look again and fix it.

Step 2. Go back and work through every part of the tutorial again, and this time explain it to your doggie. See how I am doing that in my avatar picture? If you have no dog, explain it to your house plant. If you are unable to explain any part of it, STOP. DO NOT PROCEED. Now go learn how that part works. Read the documentation on the functions involved. Go back to the tutorial and try to figure out WHY they did that. This is the part that takes a LOT of time when you are new. It might take days or weeks to work through a single 5-minute tutorial. Stick with it. You will learn.

Step 2 is the part everybody seems to miss. Without Step 2 you are simply a code-typing monkey and outside of the specific tutorial you did, you will be completely lost. If you want to learn, you MUST do Step 2.

Of course, all this presupposes no errors in the tutorial. For certain tutorial makers (like Unity, Brackeys, Imphenzia, Sebastian Lague) this is usually the case. For some other less-well-known content creators, this is less true. Read the comments on the video: did anyone have issues like you did? If there’s an error, you will NEVER be the first guy to find it.

Beyond that, Step 3, 4, 5 and 6 become easy because you already understand!

Finally, when you have errors, don’t post here… just go fix your errors! Here’s how:

Remember: NOBODY here memorizes error codes. That’s not a thing. The error code is absolutely the least useful part of the error. It serves no purpose at all. Forget the error code. Put it out of your mind.

The complete error message contains everything you need to know to fix the error yourself.

The important parts of the error message are:

  • the description of the error itself (google this; you are NEVER the first one!)
  • the file it occurred in (critical!)
  • the line number and character position (the two numbers in parentheses)
  • also possibly useful is the stack trace (all the lines of text in the lower console window)

Always start with the FIRST error in the console window, as sometimes that error causes or compounds some or all of the subsequent errors. Often the error will be immediately prior to the indicated line, so make sure to check there as well.

Look in the documentation. Every API you attempt to use is probably documented somewhere. Are you using it correctly? Are you spelling it correctly?

All of that information is in the actual error message and you must pay attention to it. Learn how to identify it instantly so you don’t have to stop your progress and fiddle around with the forum.