Is _ (single underscore) a valid C++ variable name?

Question

With gcc 4.7.2 this compiles just fine for me:

int main()
{
  int _ = 1;
  return 0;
}

Can I expect this to compile in general? I\'ve read

Answer 1

Yeah it's a valid prefix. Running

#include 

using namespace std;

int main()
{
char* _ = "Hello World";
cout << _ << endl; 
return 0;
}

prints out "Hello World" as expected. It's not a very helpful varible name but it is valid