I'm having problems with my #include statements

GCC 3.2 does not require/allow you to have a '.h' in standard C++ header files. A few examples are iostream, ostream, strstring, string, and any STL code. You still use '.h' for non-standard files which you include.

2.96 Code:

#include <iostream.h>
#include <string.h>
#include "myclass.h"

3.2 Code:

#include <iostream>
#include <string>
#include "myclass.h"

Unrecognized Symbols

I get an error about unrecognized symbols with cout, eol, cin, string, vector, etc.

Unlike GCC 2.96, version 3.2 actually requires you to write correct C++ code. One example is the use of namespaces to define scope. For example, if you are having unrecognized symbol errors with cout, you could do the following:

std::cout << "Hello, world";

This basically tells it where to look for cout; std is a namespace used by common C++ facilities. If you don't want to put std:: in front of every cout you could add the following line after your #includes:

using std::cout;

Now it knows where to get cout from. The following would set the namespace for everything in std (cout, eol, cin, etc):

``using namespace std;``

Here is a nice explanation of namespaces with example code: http://www.mvps.org/windev/cpp/nspaces.html

string::compare

Has something changed with string::compare?

In a nutshell, yes. The syntax is a little different.

2.96:

string::compare(string,start,end);

3.2:

string::compare(start,end,string);

Compatibility

I use GCC 2.96 at home and 3.2 at school (or vice-versa), how can I write code that is compatible with both?

Try something like the following:

#if (__GNUC__ >= 3)
                // Put your 3.2 code here
#else
                // Put your 2.96 code here
#endif

Changes in STL Constructs

Some of the STL Constructs I'm using don't work anymore.

hash_set, hash_map, and their related classes are not officially part of the STL, but are an extension proposed by SGI. The following changes apply to these constructs:

1. The location of the include files has changed. So #include <hash_set.h> becomes #include <ext/hash_set>.

2. The namespace is different, as well. It has changed to __gnu_cxx. Therefore: struct hash<yourClass> {...} becomes:

       namespace __gnu_cxx {
           struct hash<yourClass> {...}
       }
   
   and ``hash_set<yourClass, hash<yourClass>, ...>`` either becomes
   ``__gnu_cxx::hash_set<yourClass, __gnu_cxx::hash<yourClass>, ...>`` or you
   could add ``using namespace __gnu_cxx;`` near the top of your file, and
   leave the hash_set definition unchanged.