Bitwise shift operators: If the value of the right operand is negative or is greater than or equal to the width of the promoted left operand, the behavior is undefined.

bitshift.cpp

#include <stdio.h>

int main() {
    int n = 1;
    for (int i = 0; i < 32; i++) {
        n <<= 1;
    }
    printf("%d\n", n); // gcc: 0  msvc: 0

    int m = 1;
    m <<= 32;
    printf("%d\n", m); // gcc: 1  msvc: 1  (the behavior is undefined)

    long long lln = 1;
    for (int i = 0; i < 64; i++) {
        lln <<= 1;
    }
    printf("%lld\n", lln); // gcc: 0  msvc: 0

    long long llm = 1;
    llm <<= 64;
    printf("%lld\n", llm); // gcc: 1  msvc: 0  (the behavior is undefined)
}