Question

I am trying to understand how operator overloads works.

I want to code it so that I can write

Log(Log::LEVEL_ERR) << "fatal error: " << 13 ; 

And for both the string and the number the overloaded operator is used.

I now have

class Log{
  public:
    std::ostream& operator<<(char const*);
}

std::ostream& Log::operator<<(char const* text){
  if (Log::isToWrite()) {
    printLevel();
    std::cout << text;
  }
  return std::cout;
}

This only get’s me the string but not the number, why?

Edit
@bitmask Just to be clear, you mean implement like this:

class Log{
  public:
    friend  Log& operator<<(Log& in, char const* text);
}

friend  Log& operator<<(Log& in, char const* text){
  if (in.isToWrite()) {
    in.printLevel();
    std::cout << text;
  }
  return std::cout;
}

Because I get these everywhere now:

error: Semantic Issue: Invalid operands to binary expression (‘Log’ and ‘const char [15]’)

Maybe this is really simple but can you spell it out for me?
I’m really not getting it.

Answer 1

Because you returned an ostream&, the next << operator matches operator<<(ostream&, int). You should return *this; (type is Log&) instead, so that the next << operator matches an operator defined for your class.