extern void abort(void); extern void __assert_fail(const char *, const char *, unsigned int, const char *) __attribute__ ((__nothrow__ , __leaf__)) __attribute__ ((__noreturn__)); void reach_error() { __assert_fail("0", "MultCommutative-2.c", 3, "reach_error"); } /* * Recursive implementation multiplication by repeated addition * Check that this multiplication is commutative * * Author: Jan Leike * Date: 2013-07-17 * */ extern int __VERIFIER_nondet_int(void); // Multiplies two integers n and m int mult(int n, int m) { if (m < 0) { return mult(n, -m); } if (m == 0) { return 0; } return n + mult(n, m - 1); } int main() { int m = __VERIFIER_nondet_int(); if (m < 0 || m > 46340) { return 0; } int n = __VERIFIER_nondet_int(); if (n < 0 || n > 46340) { return 0; } int res1 = mult(m, n); int res2 = mult(n, m); if (res1 != res2 && m > 0 && n > 0) { ERROR: {reach_error();abort();} } else { return 0; } }