Question

What is the error in this file?
I get:

foo2.cpp:9: error: expected primary-expression before '(' token
foo2.cpp:9: error: expected primary-expression before 'int'
foo2.cpp:9: error: expected ';' before '{' token

int main(void)
{
  class X {
    int i;
  public:
    X(int ii = 0);
  };

  X::X(int ii) { i = ii; }
  return 0;
}

Answer 1

First, may I ask, WHY?

Second, you can’t provide an implementation inside a method (including main). If you must do this, keep the implementation inline:

int main()
{
  class X {
    int i;
  public:
    X(int ii = 0){ i = ii; }
  };
  return 0;
}