How to get a decimal answer when dividing variables.

[nathan801]

I'm writing a simple program using if statements. I can't get the 2nd condition to give an accurate answer. I'm dividing two integer variables in an attempt to use the ceil() function on the answer to round up. I keep getting 1 when dividing 240/200. The first condition works but i honestly do not know why. The numbers i have been inputting to test are 150.99 for small package, 50.99 for large package and 240 for number of invitations. Thank you in advance.

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

#define TRUE 1

int main () {

    int SMALL=50; // number of invitations in a small package
    int LARGE=200.0000; // number of invitations in a large
    int amount=0.0000; // total number of invitations
    float costSmall=0.0; // cost of a small package
    float costLarge=0.0; // cost of large package

    printf("What is the cost of a small package (in dollars)?\n");
    scanf("%f", &costSmall);
    printf("What is the cost of a large package (in dollars)?\n");
    scanf("%f", &costLarge);
    printf("How many invitations are you sending?\n");
    scanf("%d", &amount);

    double a=0.00; //number of large packages
    double b=0.00; //number of small packages

    if (costSmall < costLarge)  {
        a = amount/LARGE;
        b =(amount - a*LARGE);
        ceil(a)

    }
    if (costSmall>costLarge) {
    a=(amount/LARGE);
    b=0;




    }
    printf("\nYou should buy %.0f small package(s).\n", b);
    printf("You should buy %.0f large package(s).\n", a);
    printf("Your total cost for invitations will be $%.2f", a*costLarge+b*costSmall);

    printf("\n\n");
    system("PAUSE");
    return 0;
}

[Mathhead200]

(double)amount / LARGE or the conventional C++ way: static_cast<double>(amount) / LARGE
If you explicitly cast either operand to a double it will implicitly cast the other and invoke the double / double operation that you want.

[nathan801]

Thanks for the quick reply. So I entered:
a = (double)amount/LARGE;
b = 0;
ceil(a);

I got the same answer. I apologize to make you spell it out but it seems im obviously missing something.

[Mathhead200]

What do you think ceil(a) does? (Think carefully...) Also can you explain the decimal numbers on line 9 and 10? What is the point of assigning a compile-time constant double to an int variable?