How to Properly Overload the Angle Bracket Operator for a Template Class?

Overloading the Angle Bracket Operator for a Template Class

Trying to overload the

To resolve this, one must specify that the friend declaration applies to a specialized instance of the template class Pair with specific template arguments. This is achieved by using empty angle brackets after the operator declaration in the friend declaration.

The corrected code looks like this:

<code class="cpp">template <class t class u>
class Pair {
public:
    Pair(T v1, U v2) : val1(v1), val2(v2) {}
    ~Pair() {}
    Pair& operator=(const Pair&);
    friend ostream& operator (ostream&, Pair<t u>&);

private:
    T val1;
    U val2;
};</t></class></code>

Additionally, the function definition for the overloaded operator must be declared before the template class definition, as follows:

<code class="cpp">template <class t class u>
ostream& operator (ostream& out, Pair<t u>& v);

template <class t class u>
class Pair {
    // ...
};</class></t></class></code>

By making these changes, the compiler can correctly identify the friend function as a specialization for the Pair template and avoid the warning regarding a non-template function declaration.

The above is the detailed content of How to Properly Overload the Angle Bracket Operator for a Template Class?. For more information, please follow other related articles on the PHP Chinese website!