I defined a class template and function templates. I hope to print all types with the funciton:
template <typename T> void MyQueue<T>::Print()
{
std::vector<int>::iterator It1;
It1 = data.begin();
for ( It1 = data.begin( ) ; It1 != data.end( ) ; It1++ )
cout << " " << *It1<<endl;

}
by using vector template. Now it just works for int. How can I change it to work for typename T
std::vector<typename T>::iterator It1;
always failed.

Thank you!

/////////////////////////////////////////
#include <iostream>
#include <vector>
#include <string>
using namespace std;

template <typename T>
class MyQueue
{
std::vector<T> data;
public:
void Add(T const &);
void Remove();
void Print();
};

template <typename T> void MyQueue<T> ::Add(T const &d)
{
data.push_back(d);
}

template <typename T> void MyQueue<T>::Remove()
{
data.erase(data.begin( ) + 0,data.begin( ) + 1);
}

template <typename T> void MyQueue<T>::Print()
{
std::vector<int>::iterator It1;
It1 = data.begin();
for ( It1 = data.begin( ) ; It1 != data.end( ) ; It1++ )
cout << " " << *It1<<endl;

}
//Usage for C++ class templates
int main()
{
MyQueue<int> q;
q.Add(1);
q.Add(2);

cout<<"Before removing data"<<endl;
q.Print();

q.Remove();
cout<<"After removing data"<<endl;
q.Print();
MyQueue<string> str;
str.Add("stirng1");
str.Add("string2");

cout<<"Before removing data"<<endl;
str.Print();

str.Remove();
cout<<"After removing data"<<endl;
str.Print();
return 0;

}

You've specialised the vector in the template to int, you should pass in T.

When I changed

std::vector<T>::iterator It1;s

I got those compiling errors:

template.cpp: In member function ‘void MyQueue<T>::Print()’:
template.cpp:28: error: expected `;' before ‘It1’
template.cpp:29: error: ‘It1’ was not declared in this scope
template.cpp: In member function ‘void MyQueue<T>::Print() [with T = std::basic_string<char, std::char_traits<char>, std::allocator<char> >]’:
template.cpp:55: instantiated from here
template.cpp:28: error: dependent-name ‘std::vector<T,std::allocator<_CharT> >::iterator’ is parsed as a non-type, but instantiation yields a type
template.cpp:28: note: say ‘typename std::vector<T,std::allocator<_CharT> >::iterator’ if a type is meant

Use



Better yet use const_iterator and make Print() a const member function.

I get the same error when I compile under GCC 3.4.x. I'll try it on 4.x when I get home.

It compiles fine with Visual Studio 2005.

Thanks jsmith and kbw. Now it works with
typename std::vector<T>::iterator It1;