传值、传址和传引用

　　在编写个人函数的时候，你将受到C++中一条基本原则的限制：在默认的情况下，参数只能以值传递的方式给函数。这句话的理解是：被传递到函数的只是变量的值，永远不会是变量本身。举例如下：

#include <iostream>

void changeAge( int age, int newAge );

// 如果想要实现计划功能，需要怎么改？
 
main()
{
    int age = 24;
    std::cout << "My age is " << age << "\n";
    
    changeAge( age, age+1 );
    
    std::cout << "Now my age is " << age << "\n";
}

void changeAge( int age, int newAge )
{
    age = newAge;
    std::cout << "In this , my age is " << age << "\n";
}

My age is 24
In this , my age is 25
Now my age is 24
请按任意键继续. . .

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