unity getting a component and adding it in code code example

Example 1: unity add component

//Use the AddComponent<T>() Method to add a component to your gameobject
GameObject gameObject;

gameObject.AddComponent<BoxCollider>(); //Component has to be an actual Unity component

Example 2: c# addcomponent

// Consider an existing GameObject, gameObj
Rigidbody addedComp = gameObj.AddComponent<Rigidbody>() as Rigidbody;
// You can also add custom components by class name