CODEWITHSUNDEEP
ccs50
Matteo Rehm
Matteo Rehm

Reputation: 7

CS50: "expected prompt for input, not exit code of 0" not too sure what I am doing wrong here

I was just wondering what I did wrong here, because when the program is executed, it runs just fine. I'm a newbie at programming and am very lost. Any advise would be great!

#include <stdio.h>
#include <cs50.h>
#include <math.h>
int main(void)
{
    printf("Days in Month:\n");
    int days = GetInt();
    for (; days < 28 || days > 31; days = GetInt())
    {   
        printf("No month has that amount of days! Please try again.\n");
    }
    printf("Pennies on first day:\n");
    int pennies = GetInt();
    for (; pennies < 0; pennies = GetInt())
    {   
        printf("You can't have negative pennies! Please try again.\n");
    }
    if (pennies == 1) 
        printf("$%.2f",pow ((pennies + 1), (days - 1)));
    else 
        printf("$%.2f",pow (pennies, days));
}

Check50 yields:

~/workspace/chapter1/ $ check50 1617.chapter1.pennies pennies.c
:) pennies.c exists
:) pennies.c compiles
:( 28 days, 1 penny on first day
   \ expected output, but not "$134217728.00"
:( 31 days, 1 penny on first day
   \ expected output, but not "$1073741824.00"
:( 29 days, 2 pennies on first day
   \ expected output, but not "$536870912.00"
:( 30 days, 30 pennies on first day
   \ expected output, but not "$20589113209464899002378237447530552256..."
:) rejects days not 28, 29, 30, or 31
:( rejects non-positive pennies
   \ expected prompt for input, not exit code of 0
:) rejects a non-numeric days input of "foo"
:) rejects a non-numeric penny input of "foo"
:) rejects a non-numeric days input of ""
:) rejects a non-numeric penny input of ""

As you can see it says that it is accepting negative inputs and is not yielding the correct amount of money. Is this a bug in check50, or did I do something wrong?

Upvotes: 0

Views: 836

Answers (1)

Schwern
Schwern

Reputation: 165318

Assuming it's this assignment, your math is wrong.

The assignment is what happens if your initial amount of pennies doubles every day for a month. If you start with 5 pennies, that means 5 then 10 then 20 then 40... 5 * 2 * 2 * 2 ... or 5 * 2N where N is the number of days.

But you have pow(pennies, days). If pennies = 5 and days = 30 that's 530 which is something entirely different and very large.

What you need is pennies * pow(2, days). And that's the number of pennies, so divide by 100 to get the dollar amount.

This isn't 100% correct, but since this is an exercise I leave the rest of the details up to you.

As to the "exit 0" problem, it's this:

for (; pennies < 0; pennies = GetInt())
{   
    printf("You can't have negative pennies! Please try again.\n");
}

You're allowing 0 pennies. You're supposed to reject that.

If the user does not input a positive integer for the first day’s number of pennies, the program should prompt the user to retry.

As to why it says it didn't get a prompt, it gave you 0 pennies and expected to be prompted again. Whoever wrote the checking code didn't think to see if it got output.

Upvotes: 1

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