NetNews Usenet Archive 1992 #31/NN_1992_31.iso/spool/comp/lang/cplus/18321

Text File | 1992-12-22 | 1.5 KB | 51 lines

Path: sparky!uunet!think.com!sdd.hp.com!zaphod.mps.ohio-state.edu!not-for-mail
From: [e-mail] (Liming Ren)
Newsgroups: comp.lang.c++
Subject: Automatic conversion! Can we do this?
Date: 22 Dec 1992 15:11:52 -0500
Organization: Department of Mathematics, The Ohio State University
Lines: 39
Distribution: world
Message-ID: <[e-mail]>
NNTP-Posting-Host: function.mps.ohio-state.edu

I wrote a string class and overloaded  operator + to achive the function
of strcat(). It is my understanding that the compiler will do the conversion
from char * to string using the function I supplied. What is strange is I can
do:

string a, b("Merry");
a=b+" Chrismas";
a="C" + b;

But I can't do:   a="Merry" + " Chrismas";
The compiler complains that "pointer +pointer" and the conversion does not
happen. I tried to overload + with (char*, char*). The compiler did not
allow me. HERE is the class:

class string{
  char *str;
  int size;
 public:
  string()  {str=new char[10]; size=9;}
  string(const char *p){ str=strdup(p); size=strlen(p);}
  string(const string& s){str=strdup(s.str); size=s.size;}
  ~string(){delete [] str;}
  string& operator=(const string&s){/*body*/    }
  friend string operator+(const string&,const string&){/*body*/}
};

main()
{
  string a;
  a="Merry" +" Chrismas";
}

It seems to me the compiler has no clue what is going on if I supply two
pointers. It needs at least one operand to be string to invoke the
overloaded + on string class. Is there a way to overcome this?


Merry Christmas!