Using the vi editor, write a C program that computes and prints the factorial of a user-entered integer. More detailed specifications include:

• The factorial of an integer is defined as follows:
  • the factorial of integers less than 0 is not defined
  • the factorial of 0 is 1
  • the factorial of 1 is 1
  • the factorial of n where n > 1 is n times the factorial of (n - 1)
  • examples:
    the factorial of 3 is , which is 6
    the factorial of 5 is , which is 120
• If the user enters a negative integer, an error message should be printed and the factorial should not be computed.
• If the user enters 0 or a positive integer, the factorial should be computed and printed.
• Use the following code to get an integer value from the user and place it into an integer variable num.

    printf("Enter the number to find the factorial of: ");
    scanf("%d", &num);

  You can assume that the user will not enter anything except an integer (i.e. not a float or alphabetic letters).
• To hand in:
  • Either turn in a print out of your source code, or email me (wahls@psu.edu) the file containing your source code. If you email me the program, I will email you your score and any comments on your program sometime after the due date. I will also save a copy of your program to prevent later disputes.
  • Your code will be graded on correctness, readability, the clarity of messages printed for the user and appropriate use of comments.
• Hints: Test your program with negative numbers, 0, 1, and other positive numbers. Also, don't forget that control-c can be used to break out of an infinite loop. If your program runs for more than a few seconds, you will probably need to stop it this way.
• Extra Credit: For five points of extra credit, do the assignment again but use a different kind of loop than you used the first time. For example, if you used a for loop, use a while or a do while loop for the extra credit.

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