usr/lib/learn/C/L3.1a

#print
(Section 1.3)
The file Ref.c contains a copy of
a program to convert Fahrenheit to
Celsius that prints from 0 to 300
degrees in steps of 20.
Modify it to print from 300 down to 0
in steps of 50. Type ready when you're done.
#once #create Ref
 300  148.9
 250  121.1
 200   93.3
 150   65.6
 100   37.8
  50   10.0
   0  -17.8
#once #create Ref.c
/* print Fahrenheit-Celsius table
        for f = 0, 20, ..., 300 */
main()
{
        int lower, upper, step;
        float fahr, celsius;

        lower = 0;      /* lower limit of temperature table */
        upper = 300;    /* upper limit */
        step = 20;      /* step size */

        fahr = lower;
        while (fahr <= upper) {
                celsius = (5.0/9.0) * (fahr-32.0);
                printf("%4.0f %6.1f\n", fahr, celsius);
                fahr = fahr + step;
        }
}
#user
a.out >x
#cmp Ref x
#succeed
Here's our solution:

main()  /* Fahrenheit-Celsius 300 ... 0 by 50 */
{
        int lower, upper, step;
        float fahr;

        lower = 0;      /* lower limit of temperature table */
        upper = 300;    /* upper limit */
        step = 50;      /* step size */

        for (fahr = upper; fahr >= lower; fahr = fahr - step)
                printf("%4.0f %6.1f\n", fahr, (5.0/9.0) * (fahr-32.0));
}
#log
#next
3.1b 10