greedy.c giving unexpected result

Question

For some reason, everytime I run my code the result gives me a multiple of 4, is it rounding to 0.25 cents everytime? I checked the code with other users and it seems fine the rounding part...

./greedy Change: 1 Coins used: 4

./greedy Change: 5 Coins used: 20

./greedy Change: 10 Coins used:40

#include <stdio.h>
#include <cs50.h>
#include <math.h>

float in;
int out = 0;

int main(void){

    do{
        printf("Change: ");
        in = get_float();
    }
    while (in < 0);
    //round amount
   in = round(100 * in);

    while(in >= 25){
        in -= 25;
        out++;
    }
    while(in >= 10){
        in -= 10;
        out++;
    }
    while(in >= 5){
        in -= 5;
        out++;
    }
    while(in >= 1){
        in -= 1;
        out++;
    }
    printf("Coins used: %i\n", out);

}

Answer 1

Greedy.c is outputting what it should - if you walk through the program with in at 1, 5, 10, you should expect out to be 4 quarters, 20 quarters, and 40 quarters, respectively. (1 divided by 0.25 is 4, 5 divided by 0.25 is 20, etc.)

printf("Coins used: %i\n", out); is causing you to fail check50. You see, check50 is expecting a number, not Coins used: ... Though Coins used: may help the user understand your program, check50 is very strict and wants a number (in this case, out), not a string like Coins used:. This should push you in the right direction.

If this answers your question, hit the green checkmark! Don't forget to comment below if you still have issues/questions.

Answer 2

Your code is doing what it's meant to. For 1 dollar, it's returning 4 quarters, for five dollars, it's returning 20. Try some more odd value for input, like 0.87 (3 quarters, 1 dime, 2 cents => 6 coins).

I somewhat dislike that you store the now-integer number of cents in a floating point variable again, but that does not cause any problem here for reasonable inputs, is just inefficient.