[C++] 交換指針

編寫一個函數，令其交換兩個int指針。

交換兩個值可以使用兩種形式，一種是使用引用傳遞實參進行交換，另一種是使用指針以值傳遞的方式進行交換。

題目要求交換兩個int指針，也可以參考交換值的兩種形式。

1、使用指向指針的指針進行交換。

void swapPointerUsePointer(int **p, int **q)
{
    int *t = *p;
    *p = *q;
    *q = t;
}

2、使用引用來傳遞指針進行交換、

void swapPointerUseReference(int *&p, int *&q)
{
    int *t = p;
    p = q;
    q = t;
}

測試代碼如下：

int main()
{
    int a = 100, *p = &a;
    int b = 200, *q = &b;
    cout << "original pointer and value: " << endl;
    cout << "a: " << p << " value: " << *p << endl;
    cout << "b: " << q << " value: " << *q << endl;
    cout << endl;
    cout << "after swap by pointer the current pointer and value: " << endl;
    swapPointerUsePointer(&p, &q);
    cout << "a: " << p << " value: " << *p << endl;
    cout << "b: " << q << " value: " << *q << endl;
    cout << endl;
    cout << "after swap by reference the current pointer and value: " << endl;
    swapPointerUseReference(p, q);
    cout << "a: " << p << " value: " << *p << endl;
    cout << "b: " << q << " value: " << *q << endl;
    cout << endl;
    return 0;
}

測試結果如下：

original pointer and value:
a: 006FF780 value: 100
b: 006FF768 value: 200

after swap by pointer the current pointer and value:
a: 006FF768 value: 200
b: 006FF780 value: 100

after swap by reference the current pointer and value:
a: 006FF780 value: 100
b: 006FF768 value: 200