Does GCC support long long int?

Question

Title basically says it all... does GCC support:

long long int

which would be a 64 bit integer?

Also, is long long int part of the standard? Thanks

Answer 1

long long int is a part of the C99 standard, and I know GCC supports it. And now I can prove it.

Answer 2

Yes GCC does support long long int, which is a part of C99 standard.

The standard does not mandate its size in bits, but required values of LLONG_MIN and LLONG_MAX in <limits.h> imply it's at least 64-bit (exact 64-bit wide integer types are int64_t/uint64_t from <stdint.h>).

1. LLONG_MIN must be at most -9223372036854775807
2. LLONG_MAX must be at least 9223372036854775807

Answer 3

I believe that usually an unsigned long long is the traditional representation of a 64-bit integer. I'm assuming long long int would work too, but I've never personally seen any 64-bit vars declared that way before.

Answer 4

On my 32-bit machine,

int main()
{
    printf("%d\n", sizeof(long long int));
    return 0;
}

compiled with gcc prints 8 (8 bytes * 8 bits/byte = 64 bits).

Answer 5

Yes, long long is part of C99, as well as long long constants (10222333444555LL) and a few support elements. (LLONG_MAX, llrint(d), llround(d), some others.) And gcc has implemented it for some time now.

Answer 6

In order to print long long int variables:

long long int lli = 100000000;

printf("%lld\n", lli);

Answer 7

long longs are well supported, and have been for a long long time [sorry]. As I understand it, this should have been 128 bit on 64-bit platforms, but for compatibility/portability reasons in GCC, has standardised on a 64-bit width.

See also: (u)int128_t, and this discussion on GCC's 128-bit integer support