What will this C code do?

void main(){
int x=1;
printf("%d\n",x=2);
}

>>134
I can now see why I'm even having to argue with you with something that should be obvious. You can't read. Of course that's not an expression. "Used as an expression" means:

if (foo);
There. I used it as an expression.

Also, int foo; is an external definition, not just a declaration. Just in case you didn't know.