C++ 中通过引用传递参数

我们已经讨论了如何使用指针来实现 引用调用 的概念。这里是另一个通过引用调用的示例，它使用了 C++ 中的引用。

#include <iostream>
using namespace std;

// function declaration
void swap(int& x, int& y);

int main () {
   // local variable declaration:
   int a = 100;
   int b = 200;

   cout << "Before swap, value of a :" << a << endl;
   cout << "Before swap, value of b :" << b << endl;

   /* calling a function to swap the values.*/
   swap(a, b);

   cout << "After swap, value of a :" << a << endl;
   cout << "After swap, value of b :" << b << endl;

   return 0;
}

// function definition to swap the values.
void swap(int& x, int& y) {

   int temp;
   temp = x; /* save the value at address x */
   x = y;    /* put y into x */
   y = temp; /* put x into y */

   return;
}

当上述代码被编译并执行时，会产生以下结果−

Before swap, value of a :100
Before swap, value of b :200
After swap, value of a :200
After swap, value of b :100