how to read a key input unity code example

Example 1: unity key detection

if (Input.GetKeyDown(KeyCode.Space))
        {
            print("space key was pressed");
        }

Example 2: unity docs player input

using UnityEngine;
using System.Collections;public class ExampleClass : MonoBehaviour
{
    public void Update()
    {
        if (Input.GetButtonDown("Fire1"))
        {
            Debug.Log(Input.mousePosition);
        }
    }
}