UnityEngine.Component does not contain definition for

I copied a script from Unity’s site for camera pinch zoom but when I saved the script I got the following message in Unity.
“UnityEngine.Component does not contain a definition for” and everything that contained the word orthographic and fieldOfView was after that

Here is the script
using UnityEngine;

public class PinchZoom : MonoBehaviour
{
public float perspectiveZoomSpeed = 0.5f; // The rate of change of the field of view in perspective mode.
public float orthoZoomSpeed = 0.5f; // The rate of change of the orthographic size in orthographic mode.

void Update()
{
	// If there are two touches on the device...
	if (Input.touchCount == 2)
	{
		// Store both touches.
		Touch touchZero = Input.GetTouch(0);
		Touch touchOne = Input.GetTouch(1);

		// Find the position in the previous frame of each touch.
		Vector2 touchZeroPrevPos = touchZero.position - touchZero.deltaPosition;
		Vector2 touchOnePrevPos = touchOne.position - touchOne.deltaPosition;

		// Find the magnitude of the vector (the distance) between the touches in each frame.
		float prevTouchDeltaMag = (touchZeroPrevPos - touchOnePrevPos).magnitude;
		float touchDeltaMag = (touchZero.position - touchOne.position).magnitude;

		// Find the difference in the distances between each frame.
		float deltaMagnitudeDiff = prevTouchDeltaMag - touchDeltaMag;

		// If the camera is orthographic...
		if (camera.isOrthoGraphic)
		{
			// ... change the orthographic size based on the change in distance between the touches.
			camera.orthographicSize += deltaMagnitudeDiff * orthoZoomSpeed;

			// Make sure the orthographic size never drops below zero.
			camera.orthographicSize = Mathf.Max(camera.orthographicSize, 0.1f);
		}
		else
		{
			// Otherwise change the field of view based on the change in distance between the touches.
			camera.fieldOfView += deltaMagnitudeDiff * perspectiveZoomSpeed;

			// Clamp the field of view to make sure it's between 0 and 180.
			camera.fieldOfView = Mathf.Clamp(camera.fieldOfView, 0.1f, 179.9f);
		}
	}
}

}

Please help me

Use this instead:

 // Otherwise change the field of view based on the change in distance between the touches.
            Camera.main.fieldOfView += deltaMagnitudeDiff * perspectiveZoomSpeed;
            // Clamp the field of view to make sure it's between 0 and 180.
            Camera.main.fieldOfView = Mathf.Clamp(Camera.main.fieldOfView, 0.1f, 179.9f);