c++ stl映射编译问题与GCC/代码块

下面的代码应该与VS 2008一起工作，但我在第53行周围遇到了麻烦地点:

portMap_.erase(it);

我正在使用codeblocks/mingw/gcc 4.xx

#include<iostream>
#include<map>
#include<string>
using namespace std;
//defining a union that is used with newMap_
union uu
{
  char c;
  int i;
} u;
//Lets define two different maps
//The first parameter is key and second value
map<string, int> portMap_;
map<void *, uu> newMap_;
int main()
{
  //first entry in portmap
  portMap_["first"] = 1;
  //example of using the iterator
  map<string, int>::const_iterator it;
  string z = "second";
  it = portMap_.find(z); //not in the map so wont be found
  if(it == portMap_.end())
  {
    portMap_[z] = 22; //add second element
  }
  //Add thrid element directly
  z = "third";
  portMap_[z] = 12345;
  //Add 4th element by insert
  portMap_.insert(pair<string,int>("fourth", 4444));
  //Add 5th element by insert
  portMap_.insert(pair<string,int>("fifth", 5555));

  cout<<"n** Printing the portmap_ values **"<<endl;
  for(it = portMap_.begin(); it != portMap_.end(); ++it)
    cout<<"Key = "<<it->first<<"   Val = "<<it->second<<endl;
  cout<<"n** Removing fourth element **"<<endl;
  z = "fourth";
  it = portMap_.find(z);
  portMap_.erase(it);
  cout<<"n** Printing the portmap_ values **"<<endl;
  for(it = portMap_.begin(); it != portMap_.end(); ++it)
    cout<<"Key = "<<it->first<<"   Val = "<<it->second<<endl;
  //Playing with New Map
  cout<<"nnCreating New Map whose key is a void pointer"<<endl;
  uu u_val1, u_val2;
  void *val1, *val2;
  u_val1.i = 70, val1 = &u_val1;
  newMap_[val1]=u_val1;
  val2 = val1;
  map<void *, uu>::const_iterator it_new;
  it_new = newMap_.find(val2);
  if(it_new != newMap_.end())
  {
    u_val2 = it_new->second;
    cout<<"Note that since u_val2 is a union you can print i or c as required"<<endl;
    cout<<"val2 = "<<val2<<"    value.c = "<<u_val2.c<<endl;
    cout<<"val2 = "<<val2<<"    value.i = "<<u_val2.i<<endl;
  }
  return 0;
}

错误如下:

map_examplemap_example.cpp||In function 'int main()':|
map_examplemap_example.cpp|51|error: no matching function for call to 'std::map<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int> > >::erase(std::_Rb_tree_const_iterator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int> >&)'|
c:program filescodeblocksmingwbin..libgccmingw324.4.1includec++bitsstl_map.h|566|note: candidates are: void std::map<_Key, _Tp, _Compare, _Alloc>::erase(typename std::_Rb_tree<_Key, std::pair<const _Key, _Tp>, std::_Select1st<std::pair<const _Key, _Tp> >, _Compare, typename _Alloc::rebind<std::pair<const _Key, _Tp> >::other>::iterator) [with _Key = std::basic_string<char, std::char_traits<char>, std::allocator<char> >, _Tp = int, _Compare = std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, _Alloc = std::allocator<std::pair<const std::basic_string<char,|
c:program filescodeblocksmingwbin..libgccmingw324.4.1includec++bitsstl_map.h|581|note:                 typename std::_Rb_tree<_Key, std::pair<const _Key, _Tp>, std::_Select1st<std::pair<const _Key, _Tp> >, _Compare, typename _Alloc::rebind<std::pair<const _Key, _Tp> >::other>::size_type std::map<_Key, _Tp, _Compare, _Alloc>::erase(const _Key&) [with _Key = std::basic_string<char, std::char_traits<char>, std::allocator<char> >, _Tp = int, _Compare = std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, _Alloc = std::allocator<std::pair<const std::basic_stri|
c:program filescodeblocksmingwbin..libgccmingw324.4.1includec++bitsstl_map.h|596|note:                 void std::map<_Key, _Tp, _Compare, _Alloc>::erase(typename std::_Rb_tree<_Key, std::pair<const _Key, _Tp>, std::_Select1st<std::pair<const _Key, _Tp> >, _Compare, typename _Alloc::rebind<std::pair<const _Key, _Tp> >::other>::iterator, typename std::_Rb_tree<_Key, std::pair<const _Key, _Tp>, std::_Select1st<std::pair<const _Key, _Tp> >, _Compare, typename _Alloc::rebind<std::pair<const _Key, _Tp> >::other>::iterator) [with _Key = std::basic_string<char, std::char_traits<char>, std::all|
||=== Build finished: 1 errors, 0 warnings ===|