/*
 * Program demonstrating use of struct.
 */
#include <stdio.h>
#include <stdlib.h>

/* struct representing a fraction */
struct fraction {
    int numerator;
    int denominator;
};

/* function declarations -- comments below with definitions */
void init_fraction(struct fraction * f, int numerator, int denominator);
int print_fraction(FILE * outfile, struct fraction * f);

/* main program */
int main(void) {

    struct fraction f1;
    int numerator;
    int denominator;

    printf("enter numerator and denominator:\n");
    if (scanf("%d %d", &numerator, &denominator) != 2) {
        fprintf(stderr, "values must be numeric\n");
        return EXIT_FAILURE;
    }
    init_fraction(&f1, numerator, denominator);
    fprintf(stdout, "the fraction is ");
    print_fraction(stdout, &f1);
    fprintf(stdout, "\n");
    return EXIT_SUCCESS;
}

/* 
 * initialize instance of "fraction" structure.
 */
void init_fraction(struct fraction * f, int numerator, int denominator) {
    /* another syntax
    (*f).numerator = numerator;
    (*f).denominator = denominator;
    */
    f->numerator = numerator;
    f->denominator = denominator;
}

/* 
 * "print" instance of "fraction" structure (write in n / d to outfile),
 *   using fprintf.
 *
 * returns return value from fprintf (which is usually ignored, but
 *   return for consistency, or just in case caller wants it).
 */
int print_fraction(FILE * outfile, struct fraction * f) {
    return fprintf(outfile, "%d/%d", f->numerator, f->denominator);
}