C++阶段01笔记03【运算符（算术运算符、赋值运算符、比较运算符、逻辑运算符）】

绝地灬酷狼 2022-11-12 09:48 166阅读 0赞

> [C++| 匠心之作 从0到1入门学编程【视频+课件+笔记+源码】][C_ _ _0_1]

**目录**

3 运算符

3.1 算术运算符

示例1

示例2

示例3

3.2 赋值运算符

示例

3.3 比较运算符

示例

3.4 逻辑运算符

示例1：逻辑非

示例2：逻辑与

示例3：逻辑或

--------------------

# 3 运算符 #

> **作用：**用于执行代码的运算。
> 
> 本章我们主要讲解以下几类运算符：
> 
> <table> 
>  <thead> 
>   <tr> 
>    <th style="width:97px;"><strong>运算符类型</strong></th> 
>    <th><strong>作用</strong></th> 
>   </tr> 
>  </thead> 
>  <tbody> 
>   <tr> 
>    <td style="width:97px;">算术运算符</td> 
>    <td>用于处理四则运算</td> 
>   </tr> 
>   <tr> 
>    <td style="width:97px;">赋值运算符</td> 
>    <td>用于将表达式的值赋给变量</td> 
>   </tr> 
>   <tr> 
>    <td style="width:97px;">比较运算符</td> 
>    <td>用于表达式的比较，并返回一个真值或假值</td> 
>   </tr> 
>   <tr> 
>    <td style="width:97px;">逻辑运算符</td> 
>    <td>用于根据表达式的值返回真值或假值</td> 
>   </tr> 
>  </tbody> 
> </table>

## 3.1 算术运算符 ##

> **作用**：用于处理四则运算。
> 
> 算术运算符包括以下符号：
> 
> <table> 
>  <thead> 
>   <tr> 
>    <th style="width:68px;"><strong>运算符</strong></th> 
>    <th style="width:93px;"><strong>术语</strong></th> 
>    <th style="width:103px;"><strong>示例</strong></th> 
>    <th><strong>结果</strong></th> 
>   </tr> 
>  </thead> 
>  <tbody> 
>   <tr> 
>    <td style="width:68px;"><span style="color:#7c79e5;">+</span></td> 
>    <td style="width:93px;"><span style="color:#7c79e5;">正号</span></td> 
>    <td style="width:103px;"><span style="color:#7c79e5;">+3</span></td> 
>    <td><span style="color:#7c79e5;">3</span></td> 
>   </tr> 
>   <tr> 
>    <td style="width:68px;"><span style="color:#7c79e5;">-</span></td> 
>    <td style="width:93px;"><span style="color:#7c79e5;">负号</span></td> 
>    <td style="width:103px;"><span style="color:#7c79e5;">-3</span></td> 
>    <td><span style="color:#7c79e5;">-3</span></td> 
>   </tr> 
>   <tr> 
>    <td style="width:68px;">+</td> 
>    <td style="width:93px;">加</td> 
>    <td style="width:103px;">10 + 5</td> 
>    <td>15</td> 
>   </tr> 
>   <tr> 
>    <td style="width:68px;">-</td> 
>    <td style="width:93px;">减</td> 
>    <td style="width:103px;">10 - 5</td> 
>    <td>5</td> 
>   </tr> 
>   <tr> 
>    <td style="width:68px;">*</td> 
>    <td style="width:93px;">乘</td> 
>    <td style="width:103px;">10 * 5</td> 
>    <td>50</td> 
>   </tr> 
>   <tr> 
>    <td style="width:68px;">/</td> 
>    <td style="width:93px;">除</td> 
>    <td style="width:103px;">10 / 5</td> 
>    <td>2</td> 
>   </tr> 
>   <tr> 
>    <td style="width:68px;">%</td> 
>    <td style="width:93px;">取模(取余)</td> 
>    <td style="width:103px;">10 % 3</td> 
>    <td>1</td> 
>   </tr> 
>   <tr> 
>    <td style="width:68px;"><span style="color:#7c79e5;">++</span></td> 
>    <td style="width:93px;"><span style="color:#7c79e5;">前置递增</span></td> 
>    <td style="width:103px;"><span style="color:#7c79e5;">a=2; b=++a;</span></td> 
>    <td><span style="color:#7c79e5;">a=3; b=3;</span></td> 
>   </tr> 
>   <tr> 
>    <td style="width:68px;"><span style="color:#7c79e5;">++</span></td> 
>    <td style="width:93px;"><span style="color:#7c79e5;">后置递增</span></td> 
>    <td style="width:103px;"><span style="color:#7c79e5;">a=2; b=a++;</span></td> 
>    <td><span style="color:#7c79e5;">a=3; b=2;</span></td> 
>   </tr> 
>   <tr> 
>    <td style="width:68px;"><span style="color:#7c79e5;">--</span></td> 
>    <td style="width:93px;"><span style="color:#7c79e5;">前置递减</span></td> 
>    <td style="width:103px;"><span style="color:#7c79e5;">a=2; b=--a;</span></td> 
>    <td><span style="color:#7c79e5;">a=1; b=1;</span></td> 
>   </tr> 
>   <tr> 
>    <td style="width:68px;"><span style="color:#7c79e5;">--</span></td> 
>    <td style="width:93px;"><span style="color:#7c79e5;">后置递减</span></td> 
>    <td style="width:103px;"><span style="color:#7c79e5;">a=2; b=a--;</span></td> 
>    <td><span style="color:#7c79e5;">a=1; b=2;</span></td> 
>   </tr> 
>  </tbody> 
> </table>

### 示例1 ###

> ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDk0OTEzNQ_size_16_color_FFFFFF_t_70][]

#include <iostream>
    using namespace std;
    
    int main()
    {
    	int a1 = 10;
    	int b1 = 3;
    
    	cout << a1 + b1 << endl; // 13
    	cout << a1 - b1 << endl; // 7
    	cout << a1 * b1 << endl; // 30
    	cout << a1 / b1 << endl; // 3 两个整数相除,结果依然是整数,将小数部分去除
    
    	int a2 = 10;
    	int b2 = 20;
    	cout << a2 / b2 << endl; // 0
    
    	int a3 = 10;
    	int b3 = 0;
    	//错误！两个数相除，除数不可以为0！
    	//cout << a3 / b3 << endl; //报错，除数不可以为0。
    	
    
    	//两个小数可以相除
    	double d1 = 0.5;
    	double d2 = 0.25;
    	cout << d1 / d2 << endl; // 2 运算结果可以是整数
    
    	d1 = 0.5;
    	d2 = 0.22;
    	cout << d1 / d2 << endl; // 2.27273 运算结果可以是小数
    
    	system("pause");
    
    	return 0;
    }

> 总结：在除法运算中，除数不能为0。

### 示例2 ###

#include <iostream>
    using namespace std;
    
    int main()
    {
    	int a1 = 10;
    	int b1 = 3;
    	cout << a1 % b1 << endl; // 1
    
    	int a2 = 10;
    	int b2 = 20;
    	cout << a2 % b2 << endl; // 10
    
    	int a3 = 10;
    	int b3 = 0;
    	//两个数相除，除数不可以为0，所以做不了取模运算
    	// cout << a3 % b3 << endl; // 报错。取模运算时，除数不能为0！
    
    	//两个小数是不可以做取模运算的
    	double d1 = 3.14;
    	double d2 = 1.1;
    	// cout << d1 % d2 << endl; // 报错
    
    	system("pause");
    
    	return 0;
    }

> 总结：只有整型变量可以进行取模运算。

### 示例3 ###

#include <iostream>
    using namespace std;
    
    int main() //递增
    {
    	//1、前置递增
    	int a = 10;
    	++a;						 //让变量+1
    	cout << "a = " << a << endl; // 11
    
    	//2、后置递增
    	int b = 10;
    	b++;			   //让变量+1,等价于b = b + 1
    	cout << b << endl; // 11
    
    	//3、前值和后置的区别
    	//前置递增：先对变量进行++，再计算表达式
    	int a2 = 10;
    	int b2 = ++a2 * 10;
    	cout << "a2 = " << a2 << endl; // 11
    	cout << "b2 = " << b2 << endl; // 11 * 10 -> 110
    
    	//后置递增：先计算表达式，后对变量进行++
    	int a3 = 10;
    	int b3 = a3++ * 10;
    	cout << "a3 = " << a3 << endl; // 11
    	cout << "b3 = " << b3 << endl; // 100
    
    	system("pause");
    
    	return 0;
    }

> ![20210323174001185.png][]
> 
> 总结：前置递增先对变量进行++，再计算表达式，后置递增相反。

## 3.2 赋值运算符 ##

> **作用：**用于将表达式的值赋给变量。
> 
> 赋值运算符包括以下几个符号：
> 
> <table> 
>  <thead> 
>   <tr> 
>    <th style="width:83px;"><strong>运算符</strong></th> 
>    <th style="width:73px;"><strong>术语</strong></th> 
>    <th style="width:90px;"><strong>示例</strong></th> 
>    <th><strong>结果</strong></th> 
>   </tr> 
>  </thead> 
>  <tbody> 
>   <tr> 
>    <td style="width:83px;">=</td> 
>    <td style="width:73px;">赋值</td> 
>    <td style="width:90px;">a=2; b=3;</td> 
>    <td>a=2; b=3;</td> 
>   </tr> 
>   <tr> 
>    <td style="width:83px;">+=</td> 
>    <td style="width:73px;">加等于</td> 
>    <td style="width:90px;">a=0; a+=2;</td> 
>    <td>a=2;</td> 
>   </tr> 
>   <tr> 
>    <td style="width:83px;">-=</td> 
>    <td style="width:73px;">减等于</td> 
>    <td style="width:90px;">a=5; a-=3;</td> 
>    <td>a=2;</td> 
>   </tr> 
>   <tr> 
>    <td style="width:83px;">*=</td> 
>    <td style="width:73px;">乘等于</td> 
>    <td style="width:90px;">a=2; a*=2;</td> 
>    <td>a=4;</td> 
>   </tr> 
>   <tr> 
>    <td style="width:83px;">/=</td> 
>    <td style="width:73px;">除等于</td> 
>    <td style="width:90px;">a=4; a/=2;</td> 
>    <td>a=2;</td> 
>   </tr> 
>   <tr> 
>    <td style="width:83px;">%=</td> 
>    <td style="width:73px;">模等于</td> 
>    <td style="width:90px;">a=3; a%2;</td> 
>    <td>a=1;</td> 
>   </tr> 
>  </tbody> 
> </table>

### 示例 ###

#include <iostream>
    using namespace std;
    
    int main() // 赋值运算符
    {
    	// =
    	int a = 10;
    	a = 100;
    	cout << "a = " << a << endl; // a = 100
    
    	// +=
    	a = 10;
    	a += 2; // a = a + 2;
    	cout << "a = " << a << endl; // a = 12
    
    	// -=
    	a = 10;
    	a -= 2; // a = a - 2
    	cout << "a = " << a << endl; // a = 8
    
    	// *=
    	a = 10;
    	a *= 2; // a = a * 2
    	cout << "a = " << a << endl; // a = 20
    
    	// /=
    	a = 10;
    	a /= 2; // a = a / 2;
    	cout << "a = " << a << endl; // a = 5
    
    	// %=
    	a = 10;
    	a %= 2; // a = a % 2;
    	cout << "a = " << a << endl; // a = 0
    
    	return 0;
    }

## 3.3 比较运算符 ##

> **作用：**用于表达式的比较，并返回一个真值或假值。
> 
> 比较运算符有以下符号：
> 
> <table> 
>  <thead> 
>   <tr> 
>    <th style="width:67px;"><strong>运算符</strong></th> 
>    <th style="width:74px;"><strong>术语</strong></th> 
>    <th style="width:69px;"><strong>示例</strong></th> 
>    <th><strong>结果</strong></th> 
>   </tr> 
>  </thead> 
>  <tbody> 
>   <tr> 
>    <td style="width:67px;">==</td> 
>    <td style="width:74px;">相等于</td> 
>    <td style="width:69px;">4 == 3</td> 
>    <td>0</td> 
>   </tr> 
>   <tr> 
>    <td style="width:67px;">!=</td> 
>    <td style="width:74px;">不等于</td> 
>    <td style="width:69px;">4 != 3</td> 
>    <td>1</td> 
>   </tr> 
>   <tr> 
>    <td style="width:67px;">&lt;</td> 
>    <td style="width:74px;">小于</td> 
>    <td style="width:69px;">4 &lt; 3</td> 
>    <td>0</td> 
>   </tr> 
>   <tr> 
>    <td style="width:67px;">&gt;</td> 
>    <td style="width:74px;">大于</td> 
>    <td style="width:69px;">4 &gt; 3</td> 
>    <td>1</td> 
>   </tr> 
>   <tr> 
>    <td style="width:67px;">&lt;=</td> 
>    <td style="width:74px;">小于等于</td> 
>    <td style="width:69px;">4 &lt;= 3</td> 
>    <td>0</td> 
>   </tr> 
>   <tr> 
>    <td style="width:67px;">&gt;=</td> 
>    <td style="width:74px;">大于等于</td> 
>    <td style="width:69px;">4 &gt;= 1</td> 
>    <td>1</td> 
>   </tr> 
>  </tbody> 
> </table>

### 示例 ###

> ![20210323175933111.png][]

#include <iostream>
    using namespace std;
    
    int main() // 比较运算符
    {
    	int a = 10;
    	int b = 20;
    
    	// ==
    	cout << (a == b) << endl; // 0
    	// !=
    	cout << (a != b) << endl; // 1
    	// >
    	cout << (a > b) << endl; // 0
    	// <
    	cout << (a < b) << endl; // 1
    	// >=
    	cout << (a >= b) << endl; // 0
    	// <=
    	cout << (a <= b) << endl; // 1
    
    	return 0;
    }

> 注意：C和C++ 语言的比较运算中， “真”用数字“1”来表示， “假”用数字“0”来表示。

## 3.4 逻辑运算符 ##

> **作用：**用于根据表达式的值返回真值或假值。
> 
> 逻辑运算符有以下符号：
> 
> <table> 
>  <thead> 
>   <tr> 
>    <th style="width:62px;"><strong>运算符</strong></th> 
>    <th style="width:50px;"><strong>术语</strong></th> 
>    <th style="width:69px;"><strong>示例</strong></th> 
>    <th><strong>结果</strong></th> 
>   </tr> 
>  </thead> 
>  <tbody> 
>   <tr> 
>    <td style="width:62px;">!</td> 
>    <td style="width:50px;">非</td> 
>    <td style="width:69px;">!a</td> 
>    <td>如果a为假，则!a为真； 如果a为真，则!a为假。</td> 
>   </tr> 
>   <tr> 
>    <td style="width:62px;">&amp;&amp;</td> 
>    <td style="width:50px;">与</td> 
>    <td style="width:69px;">a &amp;&amp; b</td> 
>    <td>如果a和b都为真，则结果为真，否则为假。</td> 
>   </tr> 
>   <tr> 
>    <td style="width:62px;">||</td> 
>    <td style="width:50px;">或</td> 
>    <td style="width:69px;">a || b</td> 
>    <td>如果a和b有一个为真，则结果为真，二者都为假时，结果为假。</td> 
>   </tr> 
>  </tbody> 
> </table>

### 示例1：逻辑非 ###

#include <iostream>
    using namespace std;
    
    int main()
    {
    	//逻辑运算符 --- 逻辑非
    	int a = 10;
    	//在C++中，除了0都为真
    	cout << !a << endl; // 0
    
    	cout << !!a << endl; // 1
    
    	system("pause");
    
    	return 0;
    }

> 总结： 真变假，假变真。

### 示例2：逻辑与 ###

> ![20210323181106293.png][]

#include <iostream>
    using namespace std;
    
    int main()
    {
    	//逻辑运算符 --- 逻辑与 &&
    	int a = 10;
    	int b = 10;
    
    	cout << (a && b) << endl; // 1
    
    	a = 10;
    	b = 0;
    	cout << (a && b) << endl; // 0
    
    	a = 0;
    	b = 0;
    	cout << (a && b) << endl; // 0
    
    	//同真为真，其余为假！
    	system("pause");
    
    	return 0;
    }

> 总结：逻辑与运算符总结：同真为真，其余为假。

### 示例3：逻辑或 ###

> ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDk0OTEzNQ_size_16_color_FFFFFF_t_70 1][]

#include <iostream>
    using namespace std;
    
    int main()
    {
    	//逻辑运算符 --- 逻辑或
    	int a = 10;
    	int b = 10;
    	cout << (a || b) << endl; // 1
    
    	a = 10;
    	b = 0;
    	cout << (a || b) << endl; // 1
    
    	a = 0;
    	b = 0;
    	cout << (a || b) << endl; // 0
    
    	//逻辑或运算符总结：同假为假，其余为真！
    	system("pause");
    
    	return 0;
    }

> 逻辑或运算符总结：同假为假，其余为真。

[C_ _ _0_1]: https://blog.csdn.net/weixin_44949135/article/details/115025771
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[20210323174001185.png]: /images/20221022/d30a26051978421db3624babfd7b568a.png
[20210323175933111.png]: /images/20221022/30a59cb54a98403d8a3634c21a923718.png
[20210323181106293.png]: /images/20221022/5db57cead53f433f8fdfdc149ae6d062.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDk0OTEzNQ_size_16_color_FFFFFF_t_70 1]: /images/20221022/96f30d54c51c486fa5fcc95f197abf18.png