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今天小编为大家带来的是

C语言（十一）：常量指针与函数。

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Dear you, this is the Learning Yard New School.

Today's editor brings you the

C language (11): Constant pointers and functions.

一、思维导图

此推文关于常量指针与函数的内容主要如下：

The main content of this tweet about constant pointers and functions is as follows:

二、常量和指针

(一)、常量

1、520,‘a’,3.14是常量

2、利用宏定义,如#define PRICE 345;

3、const修饰,如const float pi=3.14;

（1）Constants

1、520, ‘a’, 3.14 are constants

2. Use macro definitions such as # define PRICE 345;

3. Const modification, such as const float pi=3.14;

(二)、指向常量的指针

无法直接修改指针的值，但是可以通过修改指针指向的地址或指针指向未被const修饰的变量的值来改变指针的值

（2） Pointer to constant

You cannot directly modify the value of a pointer, but you can change the value of the pointer by modifying the address it points to or the value of a variable that is not modified by const

(三)、常量指针

格式:* const p

指向非常量的常量指针指向的值可以被改变，即*p可变；但是自身的值无法改变，即p不能改变。

指向常量的常量指针指针自身不可被修改，指针指向的值也不可以被修改。

（开发中极少使用，因为当指针指向的是一个变量时，通过修改变量也可以修改指针）

（3）constant pointer

Format: * const p

The value pointed to by a constant pointer to a non-constant quantity can be changed, that is, * p is variable; However, its own value cannot be changed, that is, p cannot be changed.

A constant pointer to a constant cannot itself be modified, nor can the value pointed to by the pointer be modified.

(It is rarely used in development because when a pointer points to a variable, it can also be modified by modifying the variable.)

(四)指向“指向常量的常量指针”的指针

格式:* const *pp

（4） Pointer to "Constant Pointer to Constant"

Format: * const * pp

这里要注意p的地址与p中存放的地址是不同的两个东西

在这里，p中存放的地址为000000000062FE14(P),而p中的地址为000000000062FE08(&p)

Note that the address of p is different from the address stored in p

Here, the address stored in p is 0000000000 62FE14 (P), while the address stored in p is 0000000000 62FE08 (&p)

三、函数

(一)目前我们在开发中遇到的问题

（1） Problems we currently encounter in development

(二)函数的定义

类型名 函数名(参数列表)

{

函数体

}

如果没有参数还是要带上小括号

（2） Definition of functions

Type name Function name (parameter list)

{

Function body

}

If there are no parameters, use parentheses

示例:

give typical examples：

先用函数对代码进行封装再调用

Encapsulate the code with a function before calling it

(三)函数的声明

如上图第三行代码，如果被删除代码仍然可以运行；但是若将函数定义放在后面，老版编译器不能运行，但是有的编译器会执行但会给出提醒

（3） Declaration of functions

As shown in the third line of code above, if the code is deleted, it can still run; "However, if you leave function definitions behind, older compilers cannot run, but some compilers will execute them but give a reminder"

(四)函数的参数和返回值

void类型表示不返回，int类型需要返回

（4） Parameters and return values of functions

The void type indicates no return, while the int type requires a return

示例：

give typical examples：

声明参数的类型和数量一定要写；实参与形参声明变量名可以不同；遇到return语句成立立刻返回，不会执行后面的语句

The type and quantity of declared parameters must be written; The variable names declared by actual parameters and formal parameters can be different; "When a return statement is set, it returns immediately, and subsequent statements will not be executed."

结语：编者认为指针部分比较难懂，所以文章有什么问题还请大家提出来。

Conclusion: The editor thinks that the pointer part is difficult to understand, so if there is any problem in the article, please ask everyone to raise it.

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翻译：百度翻译

参考：《零基础入门学习C语言：带你学C带你飞》、哔哩哔哩小甲鱼视频、网络图片

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