Converting inches to feet
You could move the duplicated lines into a function, something like this should work:

#include &lt;stdio.h&gt;

float get_input(void)
{
    float input;

    printf("Enter a distance in inches (0 to quit): ");
    scanf("%f", &amp;input);

    return input;
}

int main()
{
    float inches, floatFeet, input;
    int feet;

    while (input = get_input())
    {
        feet = input/12;
        inches = (input-feet*12);
        floatFeet = input/12;
        printf("%d feet and %f inches or %f feet \n\n",feet,inches,floatFeet);
    }

    printf("Goodbye!\n");
}