In C code.

3. Factorial (fact.c) The factorial of a positive integer is defined as n! = n*n-1*n-2........3 + 2 + 1 and by definition 0! = 1. Write a program that prompts the user to enter an integer number and uses a function named factorial (described below) to calculate the factorial of that number. Function prototype: long factorial(int n) Sample Output: Number to calculate for: 5! = 120 5 Data Type Requirement: Input data for the factorial function is of type int, output is of type long Input Validation: Input value must be greater than equal to 0