什么是“&"在C ++中意味着什么? [英] What does '&' mean in C++?

问题描述

'&'是什么在C ++中意味着什么?

What does '&' mean in C++?

与功能内一样

void Read_wav::read_wav(const string &filename)
{

}

它在C语言中的等效含义是什么?

And what is its equivalent in C?

如果我想将上述C ++函数转换为C函数，该怎么办?

If I want to transform the above C++ function into a C function, how would I do it?

推荐答案

在这种情况下，&将变量作为引用.

In that context, the & makes the variable a reference.

通常，当您将变量传递给函数时，该变量将被复制，并且该函数将在副本上运行.函数返回时，原始变量不变.传递引用时，即使函数返回后，也不会进行复制，也不会显示该函数所做的更改.

Usually, when you pass an variable to a function, the variable is copied and the function works on the copy. When the function returns, your original variable is unchanged. When you pass a reference, no copy is made and changes made by the function show up even after the function returns.

C没有引用，但是C ++引用在功能上与C中的指针相同.实际上唯一的区别是，在使用它们时必须取消引用指针:

C doesn't have references, but a C++ reference is functionally the same as a pointer in C. Really the only difference is that pointers have to be dereferenced when you use them:

    *filename = "file.wav";

但是引用可以像原始变量一样使用:

But references can be used as though they were the original variable:

    filename = "file.wav";

表面上，引用应该永远不会为空，尽管这并非不可能.

Ostensibly, references are supposed to never be null, although it's not impossible for that to happen.

等效的C函数为:

     void read_wav(const char* filename)
     {

     }

这是因为C没有 string .在C中，通常的做法是在需要字符串时将指针发送到字符数组.与C ++中一样，如果您输入字符串常量

This is because C doesn't have string. Usual practice in C is to send a pointer to an array of characters when you need a string. As in C++, if you type a string constant

    read_wav("file.wav");

类型为 const char * .

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