c++ - What does the integer suffix J mean?

Question

I have the following source:

int main() { 000J; }

With gcc 4.8.4 it compiles without errors. I know there are suffixes like L or U, but I didn't find anything about J.

So what does it do?

Answer 1

I get a warning:

Imaginary constants are a GNU extension

The J suffix is a GNU extension, which causes the literal to be of a _Complex type.

More info here: https://gcc.gnu.org/onlinedocs/gcc/Complex.html