C++ 参数化构造函数

2025年8月29日 | 3 分钟阅读

我们知道，每当我们创建一个类时，都会生成一个默认构造函数，这在其他语言中通常是不可见的。但是，当我们自己创建一个构造函数时，我们就可以灵活地传递在主函数中创建对象时我们认为对构造函数必要的参数。创建一个参数化构造函数非常简单。我们只需在类函数中创建我们的构造函数，并传递必要的参数。

C++ 代码

// Here we are writing down the C++ Programming language code
// demonstrate the concept of Parameterized constructor in C++
#include <iostream>
using namespace std;
// the below code snippet helps us with creating the
// Parameterized constructor class in C++ language
class ParamA {
private:
// we have declared that variables b and c in private mode are
int b, c;
public:
ParamA (int b1, int c1)
{
    // we have declared that variables b and c in private mode are
    // given the values here as b1 and c1 now
b = b1;
c = c1;
}
// this is the getter to get the value for variable b when it is
// called
int getX ()
{
return b;
}
// this is the getter to get the value for variable c when it is
// called
int getY ()
{
return c;
}
};
// the main driver code functionality starts from here
int main ()
{
ParamA p1(10, 15);
cout << "the value we have created for p1.b is: " << p1. getX() << ", the value we have created for p1.b is: p1.c = " << p1.getY();
return 0;
}

输出

/ tm p/ po Rl 42 Ph db .o
the value we have created for p1.b is: 10, the value we have created for p1.b is: p1.c = 15

C++ 代码

// Here we are writing down the C++ Programming language code
// demonstrate the concept of Parameterized constructor in C++
#include <iostream>
using namespace std;
// the below code snippet helps us with creating the
// Parameterized constructor class in C++ language
class ParamCode {
public:
int x;
ParamCode (int i);
~ParamCode ();
};
ParamCode::ParamCode (int i) {
x = i;
}
ParamCode::~ParamCode() {
cout<< "After destructing the objects which are having the value of x is as follows:  " << x <<" \n";
}
// the main driver code functionality starts from here
int main () {
ParamCode t1(20);
ParamCode t2(15);
cout<< "the values for t1.x is:  "<<t1.x <<" " << "the values for t2.x is:  "<<t2.x << "\n";
return 0;
}

输出

/tmp/poRl42Phdb.o
the values for t1.x is:  20 the values for t2.x is:  15
After destructing the objects which have the value of x is as follows:  15
After destructing the objects which have the value of x is as follows:  20

C++ 代码

// Here we are writing down the C++ Programming language code
// demonstrate the concept of Parameterized constructor in C++

#include <iostream>

using namespace std;

// the below class we are creating to calculate the length of the rectangle 

class rectangle {

   private:

       double length;

       double breadth;

   public:

       // to demonstrate our concept, we are creating parameterised constructor to calculate the length of the rectangle
       rectangle(double len, double brt) {

// below code helps us with initialising the members of the private members of the class with certain variables 
                 length = len;

                 breadth = brt;

       }

       double calculateArea() {

                 return length * breadth;

       }

};

// the main driver code functionality starts from here

int main() {

       // below code snippet we have written in C++ programming language helps us with creating the objects
       // which are initialised with certain data members to make the object creation successful

       rectangle rect1(840, 18.6);

       rectangle rect2(628.5, 46);
       
       // the below couple of cout statements help us print the values after the operation is performed successfully!

       cout << "after calculating the area of rectangle 1 we have got as: " << rect1.calculateArea() << endl;

       cout << "after calculating the area of rectangle 2 we have got as: "<< rect2.calculateArea() << endl;

       return 0;

}

输出

after calculating the area of rectangle 1, we have got as 15624
after estimating the size of rectangle two, we have obtained: 28911

下一主题C++ 中的构造函数重载

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