C - The C Answer (2nd Edition) - Exercise 1-15

/* Rewrite the temperature conversion program of Section 1.2 to use a function for conversion. */

#include <stdio.h>

float celsius(float fahr);

/* print Fahrenheit-Celsius table or fahr = 0, 20, ..., 300; floating-point version */
main()
{
	float fahr;
	int lower, upper, step;
	lower = 0;    /* lower limit of temperature table */
	upper = 300;  /* upper limit */
	step = 20;    /* step size */
	fahr = lower;
	while(fahr <= upper)
	{
		printf("%3.0f %6.1f\n", fahr, celsius(fahr));
		fahr += step;
	}
}

/* celsius: convert fahr into celsius */
float celsius(float fahr)
{
	return (5.0 / 9.0) * (fahr - 32.0);
}