C ++函数参数以指针的地址作为参数。这是如何使用？它是什么？ [英] C++ function parameter takes an address of a pointer as an argument. How is this used? What is it for?

问题描述

想象一下这样的函数：

 函数（Human *& human）{
 // Implementation 
} 
  

是什么？它会用于什么？如何区别只是传递一个指针或引用？

解决方案

p>它就像一个双指针。

例如，human可以指向Jeff，而函数可以指向修改它以指向Ann。

  Human ann（Ann）; 
 
 void function（Human *& human）
 {
 human =& ann; 
} 
 
 int main（）
 {
人类jeff（Jeff）; 
 Human * p =& jeff; 
 function（p）; // p now point to ann 
 return 0; 
} 
  

Imagine a function like this:

 function(Human *&human){
      // Implementation
 }

Can you explain what exactly a *& is? And what would it be used for? How is different than just passing a pointer or a reference? Can you give a small and explanatory sample?

Thank you.

解决方案

It is like a double pointer. You're passing the pointer by reference allowing the 'function' function to modify the value of the pointer.

For example 'human' could be pointing to Jeff and function could modify it to point to Ann.

Human ann("Ann");

void function(Human *& human)
{
    human = &ann;
}

int main()
{
    Human jeff("Jeff");
    Human* p = &jeff;
    function(p);  // p now points to ann
    return 0;
}

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