ATL / WTL / STL

R.Bischoff | C++
 
.NET, Kommst du mit?

#include <iostream>
#include <string> 
#include <hash_map> 
using namespace std; 

/** BEGIN FIX **/ 
namespace std 
{ 
template<> struct hash< std::string > 
{ 
size_t operator()( const std::string& x ) const 
{ 
return hash< const char* >()( x.c_str() ); 
} 
}; 
} 
/** END FIX **/ 

hash_map <string, int> months; 
int main(void) { 
months["january"] = 31; 
months["february"] = 28; 
return 0; 
} 

namespace std {
  template<>
    size_t hash_compare<string>::operator()(const string &s) const
    {
      unsigned long retv = 0;
      for (string::const_iterator iter = s.begin();
	iter != s.end(); ++iter)
      {
        retv = 5 * retv + *iter;
      }
      return size_t(retv);
    }
}

1. use STLPort (where hash_map and hash_set have a hash comparison function defined for std::strings - and also you get nice features like debug mode, which tells you when you've made boo-boos like pushing an iterator outside a container, or used mismatched iterators)
   
2. Upgrade to VS.NET 2003. It cost me GBP19 (USD30 roughly) and was worth every penny - especially for the way more compliant compiler and faster IDE (well, I think it is - subjectively).
   

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

class cat
{
public:
	cat(int age)
		: age_(age)
	{
	}

	int get_age() const { return age_; }

private:
	int age_;
};

bool apredicate(const cat& a, const cat& b)
{
return a.get_age() < b.get_age();
}

int main()
{
	vector<cat> v;
	v.push_back(cat(0));
	v.push_back(cat(2));
	v.push_back(cat(1));
	v.push_back(cat(4));
	v.push_back(cat(3));
	v.push_back(cat(9));
	sort(v.begin(),v.end(),apredicate);
	for(int i = 0; i < v.size(); i++)
	{
		cout << v.at(i).get_age() << endl;
	}
	return 0;
}