I am working on code where I am handed a vector of pointers vector<T*>
or a map<std::string, T*>, and I have to delete the objects and set the
pointers to zero. I have been using a 'for' loop and thought it might be
instructive to write a 'deletePointer' which can be used in an algorithm
or standalone.
(code at end of mail)
I discovered I could not simply
for_each(v.begin(),v.end(),deletePointer);
but had to put in a type adapter for the vector, and this works but is
cumbersome.
However the syntax to use for deleting the pointers in the 'values' of
the map completely escapes me. Can anyone help?
thanks
shaun
#include <iostream>
#include <string>
#include <vector>
#include <map>
#include <utility>
#include <algorithm>
template <class T>
void deletePointer(T* &myPointer){
delete myPointer;
myPointer = NULL;
}
//adapter, general template for non-pointers
template <class T>
struct TypeOf{
typedef void pointee;
};
//adapter for pointer
template <class T>
struct TypeOf<T*>{
typedef T pointee;
};
using namespace std;
void print (string * elem){
cout<<*elem<<" ";
}
void printPointer(string * p){
cout<<hex<<p<<" ";
}
int main (int argc, char * const argv[]) {
string * pMyString = new string;
*pMyString = "hello";
cout << "Heres the newed string :"<<*pMyString<<endl;
cout << "with pointer value :"<<hex<<pMyString<<endl;
//Deletion with resetting the pointer:
deletePointer(pMyString);
//
cout << "The string has been deleted, and now.."<<endl;
cout << "the pointer value is :"<<hex<<pMyString<<endl;
//set up map and vector
map<int, string*> myMap;
vector<string *> myVec;
typedef string * PString;
for (int i(0);i not_eq 10; ++i){
PString pString=new string;
PString pString2=new string;
*pString = "burt";
*pString2 = "smith";
myVec.push_back(pString);
myMap.insert(make_pair(i,pString2));
}
for_each(myVec.begin(),myVec.end(),print);
cout<<endl;
for_each(myVec.begin(),myVec.end(),printPointer);
cout<<endl;
for_each(myVec.begin(),myVec.end(),deletePointer<
TypeOf<PString>::pointee >);
for_each(myVec.begin(),myVec.end(),printPointer);
cout<<endl;
//Now: how to delete a map of pointers using for_each?
return 0;
}
your containers. Then deleting takes care of itself. If you don't have