From: swarsmatt AT aol DOT com (SWars Matt)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: C++ undefined referance error
Date: 6 Feb 1998 02:52:08 GMT
Lines: 28
Message-ID: <19980206025201.VAA00812@ladder03.news.aol.com>
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References: <34DA3361 DOT EBDD575 AT megsinet DOT net>
To: djgpp AT delorie DOT com
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>Hello, could someone please tell me why djgpp won't compile this code?
>
>#include <iostream.h>
>int main()
>{
>    cout << "hello world";
>    return 0;
>}
>
>    I've been compiling C programs for a while now with no problems, but
>when I went to try c++ I got two errors:
>". . . .ex1.cpp:  undefined reference to 'cout'" and
>". . . .undefined reference to 'ostream::operator<<(char const *)'"
>
>I downloaded the c++ libraries again and the c++ executable and made
>sure to end my file with *.cpp.  Also, I checked the faq but I couldn't
>find anything about this.  As I said before, it worked fine compiling c
>programs.  Thanks, Pat
>

This is a common mistake. You see, including a header just tells the main
function that these other functions/classes/whatever exist, basically. They
still must be defined. This is where libraries come in. The problem would be
that you didn't link the library (-liostr, I think). Alternatively, you could
compile with gxx, not gcc, so that the C++ libraries are automatically linked
in.
Hope that solves your problem!