another pointer question

[adam2016]

Hi guys I'm getting the hang of pointers thanks to all the great people on this forum =) but I have one question here is my sample code

 #include <iostream>

using namespace std;


struct spaceShip{

    int position;
    int weaponPower;
    int* nextEnemy;

};

spaceShip* getNewEnemy(){

     spaceShip* p_ship = new spaceShip;
     p_ship->position = 0;
     p_ship->weaponPower = 20;
     p_ship->nextEnemy = NULL;

     return p_ship;
}

void upgradeWeapons(spaceShip* s){

      (*s).weaponPower += 30;

}


int main()
{
    spaceShip one;
    spaceShip* pointer;
    pointer = &one;

    one.weaponPower = 20;
    upgradeWeapons(pointer);

    cout << one.weaponPower << endl;
}

anyway what is the difference between passing a pointer into a function which has a pointer as the parameters like upgradeWeapons and passing a memory address into the same function both seem to work fine and I get the same result but I thought when I passed in a memory address I might get an error so how come this is legal and what is the difference?

example

int main()
{
    spaceShip one;
    spaceShip* pointer;
    pointer = &one;

    one.weaponPower = 20;
    upgradeWeapons(pointer); // LEGAL

    cout << one.weaponPower << endl;
}

and

int main()
{
    spaceShip one;
    spaceShip* pointer;
    pointer = &one;

    one.weaponPower = 20;
    upgradeWeapons(&one); // ALSO LEGAL

    cout << one.weaponPower << endl;
}

Thanks

[Peter87]

There is no difference. &one gives you a pointer to one.

[keskiverto]

Note that you could avoid pointers by using reference parameters:

void upgradeWeapons( spaceShip & s ){
      s.weaponPower += 30;
}

With the pointer version this is syntactically legal:

int main()
{
  upgradeWeapons( nullptr );
}

If it is legal, is it logically correct too?

[MikeyBoy]

anyway what is the difference between passing a pointer into a function which has a pointer as the parameters like upgradeWeapons and passing a memory address into the same function both seem to work fine and I get the same result but I thought when I passed in a memory address I might get an error so how come this is legal and what is the difference?

There is no difference. A pointer is a memory address. More specifically, a pointer is an integer, and the value of that integer is a memory address.

When you pass a pointer into a function, you are passing in a memory address.