Custom string class (C++)

Question

I\'m trying to write my own C++ String class for educational and need purposes.
The first thing is that I don\'t know that much about operators and that\'s why I want to

Answer 1

Here's what's going on:

1. The constructor is indeed called twice. Once for "hello" and once for " world". The order is undefined.
2. The CString::operator + is called on the 1st CString ("hello"), passing the second CString (" world") as it's argument. The return value of CString::operator + is a new CString
3. Since you're assigning in initialization, i.e: CString a = [CString result of operator +], c++ will just call you're copy constructor. Hence the call to CString(CString& ) that you're seeing in the debugger.

Now, that's 4 total objects just created, one for each string literal ("hello", and " world"), one for the concatenation of those (the result of the CString::operator + call, and one to hold the result (CString a = ...). Each one of those temporary objects will have it's destructor called.

As for why you're not getting the printf, I have no idea. I just copy pasted your code in this file:

#include 
#include 

[your code]

int main(int argc,char* argv[]) {
  CString a = CString("hello") + CString(" world");
  printf(a);
}

And when I ran the resulting executable, I got hello world as the output. This is on Ubuntu with g++ 4.4. Not exactly sure why under the VS debugger it's not printing anything.