mult.c

/*
 * demonstrate integer overflow with multiplication
 *
 * Matt Bishop, ECS 36A
 * April 4, 2024	original version
 */
#include <stdio.h>

int main(void)
{
	int ii, jj, kk;		/* used for integer multiplication */
	long int i, j, k;	/* used for long multiplication */

	/* compute the product using longs   */
	/* there is no integer overflow here */
	i = 222222222L;
	j = 555555555L;
	k = i * j;

	/* compute the product using ints */
	/* there is integer overflow here */
	ii = 222222222;
	jj = 555555555;
	kk = ii * jj;

	/* now show the difference */
	printf("The product should be %ld\n", k);
	printf("but with integers, it overflows: %d\n", kk);

	/* th-th-that's all, folks! */
	return(0);
}

Matt Bishop Office: 2209 Watershed Sciences Phone: +1 (530) 752-8060 Email: mabishop@ucdavis.edu

ECS 36A, Programming & Problem Solving Version of April 2, 2024 at 12:13PM

You can get the raw source code here.