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| // ConstPointerTest.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <string>
#include <iostream>
#include <map>
class A{
public:
A (std::string aName) {name = aName;}
void setName(std::string aName) {name = aName;}
std::string getName() const {return name;}
private:
std::string name;
};
class B{
public:
//You can modify the object and the pointer.
void addpA(A * aA) {
std::cout << "A * aA" << std::endl;
aA->setName("A * aA");
pAs.insert(std::make_pair(aA->getName(), aA));
cpAs.insert(std::make_pair(aA->getName(), aA));
pcAs.insert(std::make_pair(aA->getName(), aA));
pAcs.insert(std::make_pair(aA->getName(), aA));
cpAcs.insert(std::make_pair(aA->getName(), aA));
aA = NULL;
}
// Constant pointed object
void addcpA(const A * aA) {
std::cout << "const A * aA" << std::endl;
//aA->setName("const A * aA"); 'A::setName' : cannot convert 'this' pointer from 'const A' to 'A &'
//pAs.insert(std::make_pair(aA->getName(), aA)); cannot convert from 'const A *const ' to 'A *'
cpAs.insert(std::make_pair(aA->getName(), aA));
pcAs.insert(std::make_pair(aA->getName(), aA));
// pAcs.insert(std::make_pair(aA->getName(), aA)); cannot convert from 'const A *const ' to 'A *const '
cpAcs.insert(std::make_pair(aA->getName(), aA));
aA = NULL;
}
// Same as addcpA
void addpcA(A const * aA) {
std::cout << "A const * aA" << std::endl;
//aA->setName("A const * aA"); 'A::setName' : cannot convert 'this' pointer from 'const A' to 'A &'
//pAs.insert(std::make_pair(aA->getName(), aA)); cannot convert from 'const A *const ' to 'A *const
cpAs.insert(std::make_pair(aA->getName(), aA));
pcAs.insert(std::make_pair(aA->getName(), aA));
//pAcs.insert(std::make_pair(aA->getName(), aA)); cannot convert from 'const A *const ' to 'A *const '
cpAcs.insert(std::make_pair(aA->getName(), aA));
aA = NULL;
}
// Constant pointer, we can modify the object
void addpAc(A * const aA ) {
std::cout << "A * const aA" << std::endl;
aA->setName("A * const aA");
pAs.insert(std::make_pair(aA->getName(), aA));
cpAs.insert(std::make_pair(aA->getName(), aA));
pcAs.insert(std::make_pair(aA->getName(), aA));
pAcs.insert(std::make_pair(aA->getName(), aA));
cpAcs.insert(std::make_pair(aA->getName(), aA));
//aA = NULL; 'aA' : you cannot assign to a variable that is const
}
// The total constant pointer and constant object.
void addcpAc(const A * const aA) {
std::cout << "const A * const aA" << std::endl;
//aA->setName("const A * const aA"); cannot convert 'this' pointer from 'const A' to 'A &'
//pAs.insert(std::make_pair(aA->getName(), aA)); cannot convert from 'const A *const ' to 'A *'
cpAs.insert(std::make_pair(aA->getName(), aA)); // Why does it work? You loose the const pointer
pcAs.insert(std::make_pair(aA->getName(), aA)); // Why does it work? You loose the const pointer
//pAcs.insert(std::make_pair(aA->getName(), aA)); cannot convert from 'const A *const ' to 'A *const '
cpAcs.insert(std::make_pair(aA->getName(), aA));
//aA = NULL; 'aA' : you cannot assign to a variable that is const
}
private:
A* a;
std::map < std::string, A* > pAs;
std::map < std::string, const A* > cpAs;
std::map < std::string, A const * > pcAs;
std::map < std::string, A* const> pAcs;
std::map < std::string, const A* const> cpAcs;
};
int _tmain(int argc, _TCHAR* argv[])
{
B b;
A* pA = new A("pA");
const A* cpA = new A("cpA");
A const * pcA = new A("pcA");
A * const pAc = new A("pAc");
const A * const cpAc = new A("cpAc");
std::cout << "Start" << std::endl << pA->getName() << std::endl << cpA->getName() << std::endl<< pcA->getName() << std::endl << pAc->getName() << std::endl << cpAc->getName() << std::endl;
std::cout << "// pA" << std::endl;
// pA
b.addpA(pA);
b.addcpA(pA);
b.addpcA(pA);
b.addpAc(pA);
b.addcpAc(pA);
std::cout << "// cpA" << std::endl;
// cpA
//b.addpA(cpA); //cannot convert parameter 1 from 'const A *' to 'A *'
b.addcpA(cpA);
b.addpcA(cpA);
//b.addpAc(cpA); //cannot convert parameter 1 from 'const A *' to 'A *const '
b.addcpAc(cpA);
std::cout << "// pcA" << std::endl;
//pcA
//b.addpA(pcA); //cannot convert parameter 1 from 'const A *' to 'A *'
b.addcpA(pcA);
b.addpcA(pcA);
//b.addpAc(pcA); // cannot convert parameter 1 from 'const A *' to 'A *const '
b.addcpAc(pcA);
std::cout << "// pAc" << std::endl;
//pAc
b.addpA(pAc);
b.addcpA(pAc);
b.addpcA(pAc);
b.addpAc(pAc);
b.addcpAc(pAc);
std::cout << "End" << std::endl << pA->getName() << std::endl << cpA->getName() << std::endl<< pcA->getName() << std::endl << pAc->getName() << std::endl << cpAc->getName() << std::endl;
int i;
std::cin >> i;
return 0;
} |
