Why is "sizeof(double) > -1" false?

Question

int main()
{
    if(sizeof(double) > -1)
        printf("M");
    else
        printf("m");
    return 0;
}

I expected the output to be M but it is m. Can anybody please explain me the reason for the output?

https://stackoverflow.com/questions/20853451/void-main-ifsizeofint-1-printftrue-else-printffalse — KamilCuk, Mar 16 '21 at 12:34

score 3 · Answer 1 · answered Mar 16 '21 at 12:31

3

That's because sizeof returns a size_t value, that is, a unsigned integer type, so, -1 will overflow.

answered Mar 16 '21 at 12:31

Educorreia

3

In `sizeof(double) > -1`, −1 is converted to `size_t`. This is defined to wrap and not to overflow. – Eric Postpischil Mar 16 '21 at 12:34

1 Answers1