What's wrong with my code

Hi,

I am new to this forum and to programming for that matter.
I am following the CS50 (computer science) online course
from last year and I have problems with one of the assignments.
I am supposed to write a code to calculate the amount of coins
it takes to give change from certain amount of dollars inputed.
There are only 4 coins used (quarter, dime, nickel and penny).
I have found some other similar programs online but I would really
like to know what's wrong with my code.

And I can't believe that somebody asked identical question a few
minutes before me.

Code:

#include <math.h>
#include <stdio.h>

int main (void)
{
    // asks user to enter the amount and veryfies the input
    
    float dollars;
    do
    {
        printf("Enter the amount to get change for:");
        scanf("%f", &dollars);
    }
    while (dollars <= 0);
    
    // converts dollars into cents
    
    int cents = round(dollars * 100);
    
    // calculates the number of coins needed to give change
    
    int quarter = 25;
    int dime = 10;
    int nickel = 5;
    int penny = 1;
    int coins = 0;
    
    while (cents >= quarter)
    {
        cents -= quarter;
        coins++;
    }
    
    while (cents >= dime)
    {
        cents -= dime;
        coins++;
    }
    
    while (cents -= nickel)
    {
        cents -= nickel;
        coins++;
    }
    
    while (cents -= penny)
    {
        cents -= penny;
        coins++;
    }
    
    printf("%d\n", coins);

return 0;
}

Thanks for any help

Kamil

Code:

 while (dollars <= 0);

This has no effect.It is equivalent to this

Code:

 while (dollars <= 0)
  {
        
   }

Maybe this is not what you wanted to do.
Good for you that you help the other guy with the same post.

It was supposed to be the part of do-while loop

Oh you are right.Sorry :/

first your declaration is wrong.

int quarter = 25; int dime = 10;
int nickel = 5;

int penny = 1;
int coins = 0;

you have to declarate the type at the beginning, and if you want to give your variable new values just write (varible name) = (new value);
same thing with

int cents = round(dollars * 100);

Originally Posted by c-da

first your declaration is wrong.

you have to declarate the type at the beginning, and if you want to give your variable new values just write (varible name) = (new value);
same thing with

Not in C99.He can in the new standard

Originally Posted by std10093

Not in C99.He can in the new standard

thanks for the info.

Code:

while (cents -= nickel)
{
    cents -= nickel;
    coins++;
}
    
while (cents -= penny)
{
    cents -= penny;
    coins++;
}

Typos?

Bye, Andreas

Are you certain that the assignment only asks how many coins, and not how many of each type?

Originally Posted by kamil77

Code:

   while (cents -= nickel)
    {
        cents -= nickel;
        coins++;
    }
    
    while (cents -= penny)
    {
        cents -= penny;
        coins++;
    }

Think about your conditions in while loop....

Thanks Andreas and dojha00.

Thank you guys for taking your time to go through my code and pointing out the silly mistake that I have made.
Everything is working fine now. I guess what I needed was another set of eyes on it.

Regards
Kamil