/*
 * simple program illustrating integer I/O
 *
 * revision of previous example but including error checking.
 */
#include <stdio.h>
#include <stdlib.h>

int main(void) {
	int x = 10;
	int y = x*2;

    /* 
     * simple example of printing integer values 
     */

	printf("x = %d, y = %d\n", x, y);

    /* 
     * simple examples of prompting for integer values
     * notice the "&" in front of the target variable name --
     * we will talk later about what this means, but for now 
     * just be aware that it is needed!
     */

	printf("enter x\n");
    if (scanf("%d", &x) != 1) {
        printf("not a number\n");
        return EXIT_FAILURE; /* defined in stdlib.h */
    }
	printf("enter y\n");
    if (scanf("%d", &y) != 1) {
        printf("not a number\n");
        return EXIT_FAILURE;
    }
	printf("x = %d, y = %d\n", x, y);

	printf("enter x, y\n");
	if (scanf("%d %d", &x, &y) != 2) {
        printf("not a number\n");
        return EXIT_FAILURE;
    }
	printf("x = %d, y = %d\n", x, y);

	return 0;
}