Why is -2147483648 automatically promoted to long when it can fit in int?

Question

#include 

int main()
{
    printf(\"%zu\\n\", sizeof(-2147483648));
    printf(\"%zu\\n\", sizeof(-2147483647-1));
    return 0;
}

Answer 1

The number 2147483648 is too large to fit into an int, so it is promoted to long.

Then, after the number has already been promoted to long, its negative is computed, yielding -2147483648.

If you're curious, you can look at limits.h. On my platform, which uses glibc,

#  define INT_MIN       (-INT_MAX - 1)
#  define INT_MAX       2147483647

On MinGW, sizeof(long) == 4, so promotion to long won't cut it. According to the C11 standard, the value must be promoted to long long. This doesn't happen, probably because your MinGW compiler is defaulting to C90 or earlier.