I am new to templates in C++. Can anyone explain why my specialised constructor never gets executed. It works when I remove the const and reference operator.
#include<iostream>
#include<string>
using namespace std;
template<typename T>
class CData
{
public:
CData(const T&);
CData(const char*&);
private:
T m_Data;
};
template<typename T>
CData<T>::CData(const T& Val)
{
cout << "Template" << endl;
m_Data = Val;
}
template<>
CData<char*>::CData(const char* &Str)
{
cout << "Char*" << endl;
m_Data = new char[strlen(Str) + 1];
strcpy(m_Data, Str);
}
void main()
{
CData<int> obj1(10);
CData<char*> obj2("Hello");
}
The output is
Template
Template
Because you cannot bind "Hello"
to a const char*&
.
The information dyp added in comments is quite interesting:
A string literal is an array lvalue, which can be converted to a pointer prvalue. A pointer prvalue cannot bind to a non-const lvalue reference like const char* &
Which means you can actually make it work by replacing const char*&
by const char* const&
, or even const char* &&
in c++11, not sure if this is really smart in your use case though.