C/C++ 判断两个整数相乘是否溢出

判断两int相乘是否溢出，目前找到的最正确方式：int is_mul_overflow(int a, int b) {    if( a >= 0 && b >=0  ) {        return INT_MAX / a < b;    }    else if( a < 0 && b < 0 ) {        return INT_MAX / a > b;    }    else if( a * b == INT_MIN ) {        return 0;    }    else {        return a < 0 ? is_mul_overflow(-a, b) : is_mul_overflow(a, -b);    }}void check(int n1, int n2, int expect_ret, int case_n) {    int ret = is_mul_overflow(n1, n2);    if( expect_ret == is_mul_overflow(n1, n2) )        printf("test pass case:%d\n",case_n);    else        printf("test fail case:%d\n",case_n);}int main() {    int case_n = 0;    check(1, 0x80000000, 0, ++case_n);    check(-1, 0x80000000, 1, ++case_n);    check(0x80000000, -1, 1, ++case_n);    check(-1, 0x80000001, 0, ++case_n);    check(0x80000001, -1, 0, ++case_n);    check(1, 0x7fffffff, 0, ++case_n);    check(0x7fffffff, 1, 0, ++case_n);    check(2, 0x7fffffff, 1, ++case_n);    check(0x7fffffff, 2, 1, ++case_n);    check(0x7fffffff, -1, 0, ++case_n);    check(-1, 0x7fffffff, 0, ++case_n);    check(2, 0xc0000000, 0, ++case_n);    check(0xc0000000, 2, 0, ++case_n);    check(0x70000000, 2, 1, ++case_n);    check(2, 0x70000000, 1, ++case_n);    printf("%x\n", INT_MIN);    printf("%x\n", INT_MAX);    return 0;}

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原文链接: https://www.cnblogs.com/klzwj1988/archive/2011/09/12/2174134.html

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