Help with pset1 greedy.c

Question

very new to this and trying to learn, any help might be appreciated. Got through all the errors but not getting the output i need.

#include <stdio.h>
#include <cs50.h>
#define QUARTER 25
#define DIME 10
#define NICKLE 5
#define PENNY 1

int main(void)
{
    float r = 0;
    float num;
    int c = 0;
    //Get Change, negative check
    num = get_float();
    if (num < 0.00)
    {
        printf("Retry: ");
        num = get_float();
    }
    else
    {
        r = (num * 100);
    }
    //Quarter minus change check
    do
    {
         r = (r - QUARTER);
         c++;
         printf("Remainder: %f Count: %i\n", r, c);
    }
    while (QUARTER <= r);
    //Dime minus change check
    if (r > 0.00)
    {
        do
        {
            r = (r - DIME);
            c++;
            printf("Remainder: %f Count: %i\n", r, c);
        }
        while (DIME <= r);
    }
    else printf("Remainder: %f Count: %i\n", r, c);
    // Nickle minus change check
    if (r > 0.00)
    {
        do
        {
            r = (r - NICKLE);
            c++;
            printf("Remainder: %f Count: %i\n", r, c);
        }
        while (NICKLE <= r);
    }
    else printf("Remainder: %f Count: %i\n", r, c);
    //Penny minus change check
    if (r > 0.00)
    {
        do
        {
            r = (r - PENNY);
            c++;
            printf("Remainder: %f Count: %i\n", r, c);
        }
        while (PENNY <= r);
    }
    else printf("Remainder: %f Count: %i\n", r, c);
}

Answer 1

Your logic is flawed. In order to break out of a do...while loop, or any loop for that matter, there has to be something within the conditional statement that changes otherwise it will run forever. In your case, none of the variables q, t, f, o or n change at any time within your code.

If you have a value of change required and you want to see how many coins of a certain value are inside, you could do the following:

while the amount of change required is greater than the value of a coin
   subtract the value of the coin from change required
   add 1 to the coin count
repeat with other coin values until change required is 0

Also note the difference between a do...while loop and a while loop. A do...while loop will always run at least once, until it gets to the while statement at the end where it decides whether that condition is true or false. A while loop may run 0 times as the condition is evaluated before the loop is even run. Because of this, your code will add at least one coin of each value, whereas that may not actually be the desired outcome.

I would suggest that you work with one value of coin to start with, remove the other loops altogether and it will make it much easier to troubleshoot. Once it works for one type of coin, it is simple to repeat the loop for other values.