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[QUOTE="Daniel T., post: 2560804"]
[i]

// Libraries hold more than just books, but everything a
// library holds must have a code associated with it.
class Resource
{
   string code;
public:
   Resource( string code_ ): code( code_ ) { }
   virtual ~Resource() { }
   const string& getCode() const { return code; }
};

struct has_code : unary_function<Resource, int>
{
   string code;
   has_code( const string& code_ ): code( code_ ) { }
   bool operator()( const Resource& resource ) const {
      return resource.getCode() == code;
   }
};

class Library
{
   vector<Resource> resources;
public:
   bool codeExists( const string& tcode ) const {
      return find_if( resources.begin(), resources.end(),
         has_code( tcode ) ) != resources.end();
   }
};

class Book : public Resource
{
   // add whatever here
};

I am inclined to make Library a full fledged class...

bool findcode( const Library& lib, const string& tcode )
{
   for (Library::const_iterator it = lib.begin(); it != lib.end(); ++it)
      if ( it->getCode() == tcode )
         return true;
   return false;
}

(a) If all you need to know is if something with the code 'tcode' 
exists, then return a 'bool' instead of an 'int'.

(b) You don't need to cast the '*itor' into a 'Book&'

(c) You don't need to use the 'compare' member-function, simply compare 
them with operator==.

(d) 'b.getCode' needs parens after it... 'b.getCode()'[/i]
[/QUOTE]

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