C++ stl map compiler problem with GCC/codeblocks - c++

Question

The following code supposedly works with VS 2008 but I'm having trouble around line 53
where:
portMap_.erase(it);
I'm using 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<<"\n\nCreating 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;
}
Heres the error:
map_example\map_example.cpp||In function 'int main()':|
map_example\map_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 files\codeblocks\mingw\bin\..\lib\gcc\mingw32\4.4.1\include\c++\bits\stl_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 files\codeblocks\mingw\bin\..\lib\gcc\mingw32\4.4.1\include\c++\bits\stl_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 files\codeblocks\mingw\bin\..\lib\gcc\mingw32\4.4.1\include\c++\bits\stl_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 ===|

Answer 1

Your iterator is defined as const. Try a non-const iterator.
You can also erase an element by simply using a key_type. In your example, it would be:
portMap_.erase(z);

Answer 2

Try change from map<string, int>::const_iterator it; to map<string, int>::iterator it.