Check out example codes for "unity get component". It will help you in understanding the concepts better.

Code Example 1

using UnityEngine;

public class TryGetComponentExample : MonoBehaviour
{
    void Start()
    {
    	// Since Unity  2019.2 you can use TryGetComponent to check
        // if an object has a component, it will not allocate GC in 
        // the editor if the object doesn't have one.
        if (TryGetComponent(out Rigidbody rigidFound))
        {
        	// Deactivate rigidbody
            rigidFound.enabled = false;
        }
        
		// For versions below 2019.2 you can do it this way:
        // Create a variable
        Rigidbody rigidFound = GetComponent<Rigidbody>();
        
        // If the 'Rigidbody' exist in the gameobject
        if(rigidFound != null)
        {
        	// Deactivate rigidbody
            rigidFound.enabled = false;
        }
	}
}

Code Example 2

public GameObject Var; //only if the component you want is on a different gameObject

void Start(){
	Var.GetComponent<Component>(); //just GetComponent<Component>(); if the component you want is on the same object as script
}

Code Example 3

using UnityEngine;public class GetComponentExample : MonoBehaviour
{
    void Start()
    {
        HingeJoint hinge = gameObject.GetComponent(typeof(HingeJoint)) as HingeJoint;        if (hinge != null)
            hinge.useSpring = false;
    }
}

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