错误C2146：语法错误：在标识符'A1'之前缺少'，'

Question

I am trying to modify the class “cpair” and the function “Add” to be a template class and function.

#include "stdafx.h"
#include <iostream>
using namespace std;

class cpair
{
public:
    cpair(int x=0, int y=0) {A=x; B=y;}
    void print()
          {cout << A <<" "<<B<<endl;}
    int A, B;
};

void Add(cpair A1, cpair A2, cpair &R)
{
    R.A= A1.A + A2.A;
       R.B= A1.B + A2.B;
}

int _tmain(int argc, _TCHAR* argv[])
{
    cpair A1(4,5), A2(1,3), result;
    Add(A1, A2, result);
    result.print();
    return 0;
}

This is my implementation below, but I have an error C2146: syntax error : missing ',' before identifier 'A1'.

#include "stdafx.h"
#include "stdafx.h"
#include <iostream>
using namespace std;

template <class T>
class cpair
{
public:
    cpair(T x=0, T y=0) {A=x; B=y;}
    void print()
          {cout << A <<" "<<B<<endl;}
    T A, B;
};

template <class T>
void Add(T cpair A1, T cpair A2, T cpair &R)
{
    R.A= A1.A + A2.A;
    R.B= A1.B + A2.B;
}

template <class T>
int _tmain(int argc, _TCHAR* argv[])
{
    cpair A1(4,5), A2(1,3), result;
    Add(A1, A2, result);
    result.print();

    return 0;
}

How do I convert the class and function to be a template class and function?

Answer 1

Note the correct syntax for using cpair as class template and defining Add() as a function template . void Add(T cpair A1, ... is not a valid syntax, you need to declare Add() like this: void Add(cpair<T> A1, cpair<T> A2, cpair<T> &R) .

I believe this is a working version of what you wanted:

#include <iostream>
using namespace std;

template <class T>
class cpair
{
public:
    cpair(T x = 0, T y = 0) { A = x; B = y; }
    void print()
    {
        cout << A << " " << B << endl;
    }
    T A, B;
};

template <class T>
void Add(cpair<T> A1, cpair<T> A2, cpair<T> &R)
{
    R.A = A1.A + A2.A;
    R.B = A1.B + A2.B;
}

int main()
{
    cpair<int> A1(4, 5), A2(1, 3), result;
    Add(A1, A2, result);
    result.print();

    return 0;
}

Live here .