How to use the templates in a method parameter in a class

Question

I have a problem when use the templates with a method parameter inside a class.
The following is an example but not my real code which has the problem, in order to simplify the code.

Class declaration:

class Test {

public:
    Test();
    template <class T>
    void PrintData(T info);
};

Class definition:

Test::Test(){}

void Test::PrintData(T info){
    cout << info << endl;
}

When usage:

int main(){
    Test test;
    test.PrintData<const char*>("Thank you.");

    return 0;
}

The error messages:

variable or field 'PrintData' declared void
'T' was not declared in this scope

What is the problem in my code, and/or how to use the templates with the method parameter correctly ?

ravi · Accepted Answer · 2014-12-22T14:14:25.327

2

template<typename T>
void Test::PrintData(T info){

would be the correct definition of that function. Along with that include definitions also in header.

edited Dec 22 '14 at 14:14

answered Dec 22 '14 at 14:03

ravi

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score 0 · Answer 2 · answered Dec 22 '14 at 14:15

0

in class definition section where u defied your PrintData function, reference of template is required

so your definition will be like this template <class T> void Test::PrintData(T info){ cout << info << endl; }

answered Dec 22 '14 at 14:15

Abdullah

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score 0 · Answer 3 · answered Dec 22 '14 at 14:48

You need to put the definition of the template member function in the header file and it should work fine.

header:

#include <iostream>

class Test 
{
public:
    Test();
    template <class T>
    void PrintData(T info);
};

template <class T>
void Test::PrintData(T info)
{
    std::cout << info << std::endl;
}

How to use the templates in a method parameter in a class

3 Answers3