Weird initialization in C

Question

I have this piece of code and i don\'t know how it works

#include 

int main(void)
{
    int numero = ({const int i = 10; i+10;});

    printf         


        

Answer 1

It's a GCC statement expression. It executes the statements in it, and returns the value evaluated in the last statement. Thus numero is initialized to 20. If you delete the second part, there is no expression as the last statement, so it can't get a value from the statement expression.

The braces are necessary to disambiguate it from ordinary C parenthesized expressions.