C++ Pointers

Some stuff on Pointers (again).

#include <iostream>
using namespace std;

int main()
{
    string name = "Harry";  // Variable declaration
    string* ptr = &name;    // A pointer variable, with the name ptr,
                            // that stores the address of name.
                           
    // The following outputs the name, the address of name,
    // the address with the pointer and the contents of the address the
    // pointer points to. (known as de referencing the pointer).
   
    cout << name << " " << &name << " " << ptr << " " << *ptr << endl;
   
    *ptr = "Hello"; // change the value at the memory location
   
    // The following outputs the contents of the address the pointer
    // points to and also the name, which has been updated via the pointer.
    cout << *ptr << " " << name << endl;

}

Also;

#include <stdio.h>

int main()
{
    int n=5;
    int *ptr =&n;

    printf("Value of n = %d \n",n);
   
    printf("Address of n = %p \n",&n);
   
    printf("The value stored at the address %p is %d \n", &n, *ptr);
   
    printf("Lets now add 1 to n... \n");
   
    *ptr = *ptr +1;

    // *ptr++ doesn't work as expected but (*ptr)++ does.

   
    printf("The value stored at the address %p is %d \n", &n, *ptr);
   
    printf("%d \n",n == *ptr);

    return 0;
}

See also here

The following shows a value being passed as a reference

#include <iostream>
using namespace std;

void doSomething(int&);

int main()
{
    int i = 10;
    cout << i << endl;
    doSomething(i); 
    return 0;
}

void doSomething(int& i)  // receives i as a reference
{
    cout << i << endl;
}

The following shows a value being passed as a pointer

#include <iostream>
using namespace std;

void doSomething(int*);

int main()
{
    int i = 10;
    cout << i << endl;
    doSomething(&i);
}

void doSomething(int* i)
{
     cout << *i << endl;
}