C++ 使用参数化构造函数初始化对象数组

我们需要在定义数组时创建对象，因为在定义类时，我们需要注意不会分配任何存储空间。因此，使用类创建对象变得至关重要。在C++中，有多种方法可以使用参数化构造函数初始化对象数组；下面分别讨论了每种方法以及它们相应的C++代码和输出。

1. 使用函数调用

C++代码

// The below code demonstrates the Concept of How to initialise an Array of 
// objects with parameterized constructors in C++
#include 
using namespace std;

class Test {
    // The below variables are private.
private:
private y;

public:
    // The below code snippet is a parameter for our concept
    Test(int cx, int cy)
    {
        x = cx;
        y = cy;
    }
    // The below code snippet helps us with creating a 
    // method to add two numbers for our objects
    void add() { cout << x + y << endl; }
};
int main()
{

   // the below code helps us with initializiinitialisingects which are 
   // about three in number with the help of function calls of the 
   // constructor, which is a parameterised function which has
   // the array elements 
    Test obj[] = { Test(11, 11), Test(12, 12), Test(13, 13) };


    // the in-built add method helps us with adding up the elements of the 
    // array
    for (int i = 0; i < 3; i++) {
        obj[i].add();
    }

    return 0;
}

输出：

/tmp/2y4t0S9PoQ.o
22
24
26

2. 使用函数malloc()

C++代码

// The below code demonstrates the Concept of How to initialise an Array of 
// objects with parameterized constructors in C++
#include 
#define N 15

using namespace std;

class Test {
// The below variables are private.
    int x, y;

public:
// The below code snippet is a parameter for our concept
    Test(int x, int y)
    {
        this->x = x;
        this->y = y;
    }

    // The below function helps us to print the values 
    void print() { cout << x << " " << y << endl; }
};

int main()
{

    // the below code snippet allocates a dynamic array 
    // which is of size N using the
    // pre-defined malloc() function
    Test* arr = (Test*)malloc(sizeof(Test) * N);


    // the below code snippet calls the constructor in the
// for loop ranging from index 0 to N for each index of the array declared
    for (int i = 0; i < N; i++) {
        arr[i] = Test(i, i + 1);
    }


    //The below function helps us to print the content in our array declared
    for (int i = 0; i < N; i++) {
        arr[i].print();
    }

    return 0;
}

输出：

/tmp/2y4t0S9PoQ.o
0 1
1 2
2 3
3 4
4 5
5 6
6 7
7 8
8 9
9 10
10 11
11 12
12 13
13 14
14 15

3. 使用 NEW 关键字

C++ 代码

// The below code demonstrates the Concept of How to initialise an Array of 
// objects with parameterized constructors in C++

#include 
#define N 15

using namespace std;

class Test {
// The below variables are private.
    int x, y;

public:
    // below, we have created a dummy constructor for testing purposes 
    Test() {}

    // The below code snippet is a parameter for our concept

    Test(int x, int y)
    {
        this->x = x;
        this->y = y;
    }

    // The below function helps us to print the values 
    void print() { cout << x << " " << y << endl; }
};

int main()
{
    // the below code snippet allocates a dynamic array 
    // which is of size N using the 
    // using the new keyword
    Test* arr = new Test[N];

    // the below code snippet calls the constructor in the
// for loop ranging from index 0 to N for each index of the array declared

    for (int i = 0; i < N; i++) {
        arr[i] = Test(i, i + 1);
    }


//The below function helps us to print the content in our array declared
    for (int i = 0; i < N; i++) {
        arr[i].print();
    }

    return 0;
}

输出：

/tmp/2y4t0S9PoQ.o
0 1
1 2
2 3
3 4
4 5
5 6
6 7
7 8
8 9
9 10
10 11
11 12
12 13
13 14
14 15