maximum value of int

Why not write a piece of code like:

int  max_neg = ~(1 << 31);
int  all_ones = -1;
int max_pos = all_ones & max_neg;

#include <iostrema>

int main(){
    int32_t maxSigned = -1U >> 1;
    cout << maxSigned << '\n';
    return 0;
}

It might be architecture dependent but it does work at least in my setup.