How to define C++ template class?

Template classes allow developers to create reusable code. They only need to define a template class, include the type parameter as a template parameter in angle brackets, and provide the actual type when instantiating. You can use the template class to store different types of data. and operations.

How to define a C++ template class

Template is a powerful tool in C++ that allows you to create reusable code without No need to write separate classes or functions for each type. In this article, we will explore how to define a C++ template class.

Syntax

The syntax for defining a template class is as follows:

template<typename T>
class ClassName {
    // 模板类的代码
};

where T is a type parameter, which represents the template class Can be used with any type.

Example

Let us create a template class that can store and print any type of data:

template<typename T>
class ValueHolder {
public:
    ValueHolder(T value) : value(value) {}

    void printValue() {
        std::cout << value << std::endl;
    }
private:
    T value;
};

Now, we can Using the ValueHolder template class:

int main() {
    ValueHolder<int> intHolder(42);
    intHolder.printValue();  // 输出：42

    ValueHolder<std::string> stringHolder("Hello, world!");
    stringHolder.printValue();  // 输出：Hello, world!

    return 0;
}

Here we create two ValueHolder instances: one for the int type and the other for In std::string type. Both instances are capable of storing and printing values ​​of their corresponding types.

Restrictions in template classes

• Template classes only allow template parameters to be types, not variables or constants.
• Template parameters must be used within the scope of the template class.
• All instances in a template class must have the same type parameters.

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