How does generic programming in C++ achieve code reuse through class templates?

Generic programming allows code that uses different types of data to be implemented by creating class templates, where T is the type parameter. The syntax for creating a class template is: template class MyClass {/class definition/}. To use a class template, instantiate it with a concrete type: MyClass myIntClass. In practice, you can use the class template ArrayMultiplier to multiply the elements in the array by a specific value without specifying the type of the array element: ArrayMultiplier myMultiplier; myMultiplier.multiply(arr, arrSize, multiplier).

Using Class Templates to Implement Generic Programming in C

Generic programming is a technique that allows you to write usable codes for different types of data. This can be achieved by creating a class template that defines a class with type parameters.

Creating a class template

To create a class template you need to use the following syntax:

template <typename T>
class MyClass {
    // 类定义
};

Here, T is Type parameters, which will be replaced with concrete types.

Using Class Templates

To use a class template, instantiate it using a concrete type. For example:

MyClass<int> myIntClass;

This will create an instance of MyClass with T replaced by int.

Practical Case

Let us consider a function that multiplies the elements in an array by a certain value:

void multiplyArray(int* arr, int size, int factor) {
    for (int i = 0; i < size; i++) {
        arr[i] *= factor;
    }
}

This function can only be used with integers array. To make it universal for any type of data, we can use a class template:

template <typename T>
class ArrayMultiplier {
public:
    void multiply(T* arr, int size, T factor) {
        for (int i = 0; i < size; i++) {
            arr[i] *= factor;
        }
    }
};

To use this class, we instantiate ArrayMultiplier and call the multiply method:

ArrayMultiplier<int> intMultiplier;
int arr[] = {1, 2, 3};
intMultiplier.multiply(arr, 3, 10);

Now this code can be used for any type of array without any modification.

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