> For the complete documentation index, see [llms.txt](https://mqjyl2012.gitbook.io/algorithm/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mqjyl2012.gitbook.io/algorithm/c-cpp/c++-syntax/pointers-and-references.md).

# 指针 & 引用

## :pencil2: 1、指针

## :pencil2: 2、引用

### :pen\_fountain: 2.1、引用和指针的区别

1. 指针是一个实体，需要分配内存空间。引用只是变量的别名，不需要分配 内存空间；
2. 引用在定义的时候必须进行初始化，并且不能够改变。指针在定义的时候 不一定要初始化，并且指向的空间可变（注：不能有引用的值不能为 NULL）；
3. 有多级指针，但是没有多级引用，只能有一级引用； 
4. 指针和引用的自增运算结果不一样。（指针是指向下一个空间，引用时引 用的变量值加 1）； 
5. sizeof 引用得到的是所指向的变量（对象）的大小，而 sizeof 指针得 到的是指针本身的大小；
6. 引用访问一个变量是直接访问，而指针访问一个变量是间接访问；
7. 使用指针前最好做类型检查，防止野指针的出现； 
8. 引用底层是通过指针实现的； 
9. 作为参数时也不同，传指针的实质是传值，传递的值是指针的地址；传引 用的实质是传地址，传递的是变量的地址。

### :pen\_fountain: 2.2、左值引用和右值引用


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