How to use friend functions in class templates?
Apr 17, 2024 am 10:36 AM
Use friend functions in class templates to allow external functions to access private members. Steps: Declare a friend function: Use the "friend" keyword in the class template. Define friend functions: Use the type parameters of the class template to make it applicable to all types. Use friend functions: Call friend functions just like calling ordinary member functions.
Use friend functions in class templates
Use friend functions in class templates to allow external functions to access the class template Private member. Here's how to declare and use friend functions in a class template:
#include <iostream>
template <typename T>
class MyClass {
private:
T data;
public:
// 聲明友元函數(shù)
friend void print(const MyClass<T>& object);
// 成員函數(shù)
void set_data(const T& value) { data = value; }
};
// 友元函數(shù)定義
template <typename T>
void print(const MyClass<T>& object) {
std::cout << "Data: " << object.data << std::endl;
}
int main() {
MyClass<int> obj;
obj.set_data(10);
print(obj); // 調(diào)用友元函數(shù)
MyClass<std::string> strObj;
strObj.set_data("Hello!");
print(strObj); // 調(diào)用友元函數(shù)
return 0;
}Output:
Data: 10 Data: Hello!
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