Question

#include <stdio.h>
int main()
{
    long long x = 0x8ce4b16b;
    long long y = x<<4;
    printf("%lx, %lx, abc\n", x, y);
    return 0;
}

I’m getting
8ce4b16b, 0, abc… Is this okay?

However if I change printf like printf("%lld, %lx, abc\n", x, y);

The output becomes:
2363797867, ce4b16b0, abc

Why could have been this behaviour!! 🙁

Answer 1

Using incorrect format specifier in printf invokes Undefined Behaviour. The correct format specifier for long long is %lld.

Also make sure that you dont have signed integer overflow in your code because that’s UB too.