函數的Call By Value、Call By Address 及Call By Reference 和指標、參照之間的關係，常常讓人暈頭轉向。蔡明志大師這本「指標的藝術」講解得深入淺出，值得一讀。以下我引用此書p.206-p.208的一個例子，再稍做修改，讓同學們可以藉由簡易圖示更加容易明白。如果能看原文，那當然是最好的啦!

Call By Value 、 Call By Address 、 Call by Reference

#include <iostream>

using namespace std;

void swap_by_address(int *, int*);

void swap_by_reference(int &, int &);

void swap_by_value(int, int);

int main()

{

      int x=100, y=200;

    /* Call by value */

      x=100; y=200;

      cout << "Call by value ";

    swap_by_value(x, y);  

      cout << "x=" << x << ", y=" << y << endl;

      /* Call by address */

      x=100; y=200;

      cout << "Call by address ";

    swap_by_address(&x, &y);

      cout << "x=" << x << ", y=" << y << endl;

      /* Call by reference */

      x=100; y=200;

      cout << "Call by reference ";

    swap_by_reference(x, y);  

      cout << "x=" << x << ", y=" << y << endl;

    system("pause");

    return 0;

}

     

void swap_by_value(int a, int b) {       int temp;       temp = a;       a = b;       b = temp; }

 

void swap_by_address(int *a, int *b) {       int temp;       temp = *a;       *a = *b;       *b = temp; }

 

void swap_by_reference(int &a, int &b) {       int temp;       temp = a;       a = b;       b = temp; }