My First C Program

For this assignment, you will write a C program called first.c. This program reads two numbers from the user, and produces a few arguably-interesting facts about the numbers. See the example output for the exact output expected from your program.

Here’s an outline for the program:

Read in the two numbers.
If either number is 4, complain and stop.
Say what the numbers are.
Display the result of dividing the first number by the second one, using floating-point division. What if the second number is zero? Check the examples.
Display the positive difference of the two numbers.
Display which numbers are divisible by seven. This one is tricky. Look carefully at the examples, below. What should you print if one is divisible and one isn’t? What if both are divisible? Read the examples, below. For the record: 11 is not divisible by seven, but 14, 0, and -28 are.

Examples

Here are a few example runs of the program. Underlined text is typed by the user, the “%” is the command prompt, the rest is from the program. (You don’t have to make it underlined—that’s just how it looks here, so you can tell who does what.) Don’t be creative about your output—it must look exactly like this (except for the leading spaces):

    % c99 first.c
    % ./a.out
    Enter numbers: 21 105
    Your numbers are 21 and 105
    21 divided by 105: 0.200000
    Difference: 84
    Both are divisible by seven.
    % ./a.out
    Enter numbers: 17 12
    Your numbers are 17 and 12
    17 divided by 12: 1.416667
    Difference: 5
    Neither is divisible by seven.
    % ./a.out
    Enter numbers: 14 -3
    Your numbers are 14 and -3
    14 divided by -3: -4.666667
    Difference: 17
    14 is divisible by seven, however, -3 isn't.
    % ./a.out
    Enter numbers: 4 7
    Bad luck!
    % ./a.out
    Enter numbers: 60 0
    Your numbers are 60 and 0
    60 divided by zero: boom!
    Difference: 60
    60 isn't divisible by seven, but 0 is.
    %

Requirements

You must turn in the .c file; not the binary, not the executable, not the a.out.
Your program must be named: first.c
We will only test your code with integer input.
We will test your program with several different sets of numbers, not necessarily listed above.
You must comment your code appropriately, including your name, date and purpose of the program at the very very very beginning of the file.
You may ONLY use two int variables, declared in main, in your entire program. No other variables, of any type, are allowed.
Your output should be exactly the same as the examples above, given the input as specified.

A Brief Conversation About Requirements

“You’re not serious about only two variables, are you?”
“I'm serious.”
“That can’t be done!”
“Can too.”

“Surely, you don’t mean exactly the same output. Close is good enough, right?”
“No, I mean super-duper-mega-totally-exactly the same.”
“Well, you don’t care about upper/lower case, right?”
“I do care.”
“You can’t take off points for spelling!”
“Sure, I can. Copy what you see in the assignment.”
“Well, you don’t care about spaces, right?”
“I care about spaces, too.”
“What about periods?”
“Those matter, as well.”
“You mean that everything has to be exactly the same?”
“Yes, that’s what I meant to say.”

“What do you mean by the very very very beginning of the file?”
“Dear oh dear.”

How to submit your homework:

Follow the directions on the homework page.

How to receive negative points:

Turn in someone else’s work.

CS156: Intro to C, Part I