Thread: ofstream a_file Help

How can i get the file name to be the id number? I have tried ofstream a_file(id".txt"); but got an error. Thanks.

#include <iostream.h>
#include <fstream.h>

int main()
{
int id=0;

id++;

ofstream a_file("example.txt");
a_file<<"hello:
a_file.close();

return 0;
}