Easy tutorial for C / C ++ - class 6 (Dynamic memory allocation 2)

Easy tutorial for C / C ++ - class 6 (Dynamic memory allocation 2)

- The 'new' operator is used for dynamic memory allocation in the constructor, and the 'delete' operator is used to release the memory in the destructor. Let's look at a simple example.

Example Code

#include <iostream>

#include <iomanip>

using namespace std;

class t_Class{

   private :

     int n;

     int *p;

   public :

     t_Class(int, int);

     ~t_Class();

     void prn();

};

t_Class::t_Class(int num, int ini){

    p = new int[num];

    n = num ;

    for(int i = 0; i < n; i++){

         p[i] = ini;

         }

}

void t_Class::prn(){

    cout << " Size           : " << n << endl ;

    cout << " Initial values : " << endl;

    cout << endl;

    for(int i = 0; i < n; i++){

    cout << " p[" << i << "] = " << p[i] << endl;

         }

}

t_Class::~t_Class(){

    delete []p;

}

int main() {

     int n, v;

     cout << " Size           : " ;

     cin >> n ;

     cout << " Initial values : " ;

     cin >> v ;

     cout << endl;

     t_Class x(n,v);

     x.prn();

     return 0;

}

- A class 't_Class' was declared. And integer variable 'n' as member variable and pointer variable 'p' to be used for dynamic memory allocation were also declared.

- Let's create a constructor with two integer arguments. The argument 'num' indicates the size of the array to be allocated dynamic memory. The argument 'ini' represents the initial values of the array to be created. We used 'for loop' to initialize each element of array by 'ini'.

- Use the output function 'prn ()' to check that the size of the array and the initial value appear correctly. And in the destructor, we use the 'delete' operator to release the allocated memory.

- Declared two integer variables 'n' and 'v' in the main function. I will use the 'cin' object to input the size and initial value of the array with the keyboard.

- The object 'x' is declared and given 'n' and 'v' as arguments. Let's check the output through the output function 'prn ()'.

results :

 Size        :

- You will be prompted to enter the size of the array. Let's enter 7 here.

 Size        : 7

 Initial values :

- You are prompted to enter the initial value of the array. Enter 1 here and press Enter.

 Size           : 7

 Initial values : 1  

 Size           : 7

 Initial values :

 p[0] = 1

 p[1] = 1

 p[2] = 1

 p[3] = 1

 p[4] = 1

 p[5] = 1

 p[6] = 1

- An array of size 7 is created and the values of array elements are initialized to 1.