C program to convert Fahrenheit to Celsius always prints zero

I need some help with a program for converting Fahrenheit to Celsius in C. My code looks like t开发者_运维知识库his

#include <stdio.h>
int main(void)
{
    int fahrenheit;
    double celsius;

    printf("Enter the temperature in degrees fahrenheit:\n\n\n\n");
    scanf("%d", &fahrenheit);
    celsius = (5 / 9) * (fahrenheit - 32);
    printf("The converted temperature is %lf\n", celsius);

    return 0;
}

Every time I execute it it the result is 0.000000. I know I'm missing something but can't figure out what.

5/9 will result in integer division, which will = 0

Try 5.0/9.0 instead.

You problem is here :

celsius = (5/9) * (fahrenheit-32);

5/9 will always give you 0. Use (5.0/9.0) instead.

try celsius = ((double)5/9) * (fahrenheit-32); Or you can use 5.0.

The fact is that "/" looks at the operand type. In case of int the result is also an int, so you have 0. When 5 is treated as double, then the division will be executed correctly.

write 5/9.0 instead of 5/9 -- this forces double division

You need to use floating point arithmetic in order to perform these type of formulas with any accuracy. You can always convert the final result back to an integer, if needed.

When dealing with floats, it needs to be 5.0f / 9.0f.

When dealing with doubles, it needs to be 5.0 / 9.0.

When dealing with integers, remainders/fractions are always truncated. 5 / 9 results between 0 and 1, so it is truncated to just 0 every time. That multiplies the other side by zero and completely nullifies your answer every time.