Using Of Pointers in Functions

/*
  Write a program using pointers to input any number
  and then pass that number to the function which will
  increment the value pointed by that pointer by 1
*/
#include<iostream.h>

void increment(int* p);        // function declaration
int main(){
   int a;
  
   int* p=&a;    // declaring pointer p and intializing it to address of integer a
  
   cout << " Enter a number: ";
   cin >> a;
  
   cout << endl << "You have enetered: " << a << endl;
  
   increment(p);
  
   cout << endl << "Value after incrementing is: " << a << endl;
  
   // Another way to call for function is to send the address like below
  
   increment(&a);
  
   cout << endl << "Value after second increment is: " << a << endl;
         
return 0;
} // end main()

// ========= increment() ================
void increment(int* p1){
   (*p1)++;
return;
} // end increment()