掌握 C++ 运算符：六大类型全解析与实战示例

C++ 运算符完全指南

系统学习 C++ 六大类运算符：算术、赋值、关系、逻辑、位运算及其他，附完整示例表格与优先级陷阱避坑指南。

运算符是对变量/值执行操作的符号。如 + 执行加法，- 执行减法。

C++ 运算符分 6 类：

1. 算术运算符
2. 赋值运算符
3. 关系运算符
4. 逻辑运算符
5. 位运算符
6. 其他运算符

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1. 算术运算符

执行数学运算：

运算符	操作
+	加法
-	减法
*	乘法
/	除法
%	取模（求余）

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示例 1：算术运算符

#include <iostream>
using namespace std;

int main() {
    int a = 7, b = 2;
    cout << "a + b = " << (a + b) << endl;
    cout << "a - b = " << (a - b) << endl;
    cout << "a * b = " << (a * b) << endl;
    cout << "a / b = " << (a / b) << endl;
    cout << "a % b = " << (a % b) << endl;
    return 0;
}

输出

a + b = 9
a - b = 5
a * b = 14
a / b = 3
a % b = 1

除法细节：整数除整数得商（截断）；任一操作数为浮点数则得浮点结果。

7/2 = 3
7.0/2 = 3.5
7/2.0 = 3.5
7.0/2.0 = 3.5

取模细节：% 仅用于整数。9 % 4 = 1。

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自增/自减运算符

• ++ 增加 1
• -- 减少 1

示例：int num = 5; ++num; // 6

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示例 2：前缀/后缀自增自减

#include <iostream>
using namespace std;

int main() {
    int a = 10, b = 100, result_a, result_b;
    result_a = ++a;  // 前缀：先增后用
    cout << "result_a = " << result_a << endl;
    result_b = --b;  // 前缀：先减后用
    cout << "result_b = " << result_b << endl;
    return 0;
}

输出

result_a = 11
result_b = 99

后缀形式（a++、b--）先用后增/减。详见 自增自减详解。

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2. 赋值运算符

将值赋给变量：a = 5;

运算符	示例	等价于
=	a = b;	a = b;
+=	a += b;	a = a + b;
-=	a -= b;	a = a - b;
*=	a *= b;	a = a * b;
/=	a /= b;	a = a / b;
%=	a %= b;	a = a % b;

---

示例 3：复合赋值

#include <iostream>
using namespace std;

int main() {
    int a = 2, b = 7;
    cout << "a = " << a << endl;
    cout << "b = " << b << endl;
    cout << "\nAfter a += b;" << endl;
    a += b;  // a = a + b
    cout << "a = " << a << endl;
    return 0;
}

输出

a = 2
b = 7
After a += b;
a = 9

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3. 关系运算符

比较两个操作数关系，结果为 true(1) 或 false(0)。

运算符	含义	示例
==	等于	3 == 5 → false
!=	不等于	3 != 5 → true
>	大于	3 > 5 → false
<	小于	3 < 5 → true
>=	大于等于	3 >= 5 → false
<=	小于等于	3 <= 5 → true

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示例 4：关系运算符

#include <iostream>
using namespace std;

int main() {
    int a = 3, b = 5;
    bool result;
    result = (a == b); cout << "3 == 5 is " << result << endl;
    result = (a != b); cout << "3 != 5 is " << result << endl;
    result = (a > b);  cout << "3 > 5 is " << result << endl;
    result = (a < b);  cout << "3 < 5 is " << result << endl;
    result = (a >= b); cout << "3 >= 5 is " << result << endl;
    result = (a <= b); cout << "3 <= 5 is " << result << endl;
    return 0;
}

输出

3 == 5 is 0
3 != 5 is 1
3 > 5 is 0
3 < 5 is 1
3 >= 5 is 0
3 <= 5 is 1

---

4. 逻辑运算符

组合多个条件，结果为 true(1) 或 false(0)。

运算符	示例	含义
&&	expr1 && expr2	逻辑与：全真才真
||	expr1 || expr2	逻辑或：一真即真
!	!expr	逻辑非：真变假，假变真

真值表速查：

a=5, b=8 时：
(a>3) && (b>5)  → true
(a>3) && (b<5)  → false
(a>3) || (b>5)  → true
(a>3) || (b<5)  → true
(a<3) || (b<5)  → false
!(a<3)           → true
!(a>3)           → false

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示例 5：逻辑运算符

#include <iostream>
using namespace std;

int main() {
    bool result;
    result = (3 != 5) && (3 < 5);  cout << "(3 != 5) && (3 < 5) is " << result << endl;
    result = (3 == 5) && (3 < 5);  cout << "(3 == 5) && (3 < 5) is " << result << endl;
    result = (3 == 5) && (3 > 5);  cout << "(3 == 5) && (3 > 5) is " << result << endl;
    result = (3 != 5) || (3 < 5);  cout << "(3 != 5) || (3 < 5) is " << result << endl;
    result = (3 != 5) || (3 > 5);  cout << "(3 != 5) || (3 > 5) is " << result << endl;
    result = (3 == 5) || (3 > 5);  cout << "(3 == 5) || (3 > 5) is " << result << endl;
    result = !(5 == 2);              cout << "!(5 == 2) is " << result << endl;
    result = !(5 == 5);              cout << "!(5 == 5) is " << result << endl;
    return 0;
}

输出

(3 != 5) && (3 < 5) is 1
(3 == 5) && (3 < 5) is 0
(3 == 5) && (3 > 5) is 0
(3 != 5) || (3 < 5) is 1
(3 != 5) || (3 > 5) is 1
(3 == 5) || (3 > 5) is 0
!(5 == 2) is 1
!(5 == 5) is 0

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5. 位运算符

对整数二进制位逐位操作，仅适用 char、int 等整型。

运算符	描述
&	按位与
|	按位或
^	按位异或
~	按位取反（一补数）
<<	左移
>>	右移

详见 C++ 位运算符专题。

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6. 其他常用运算符

运算符	描述	示例
sizeof	返回类型/表达式字节大小	sizeof(int); // 4
?:	三元条件运算符	string s = (5 > 0) ? "even" : "odd"; // "even"
&	取地址	# // num 的地址
.	结构体/类成员访问	s1.marks = 92;
->	指针成员访问	ptr->marks = 92;
<<	输出流插入	cout << 5;
>>	输入流提取	cin >> num;
,	逗号运算符（顺序求值，取最后值）	int x = (a=1, b=2, a+b); // 3
.* / ->*	成员指针访问	高级元编程

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运算符优先级与结合性（核心避坑点）

高优先级先结合。常见易错点：

• == 优先级 低于 &、|、^ → a & b == 0 实为 a & (b == 0)，需加括号 (a & b) == 0
• && 优先级 高于 ||
• ?: 优先级 极低，赋值时常需括号：int x = cond ? a : b; 正确，但 x = cond ? a : b = c; 解析为 x = cond ? a : (b = c)
• 后缀 ++/-- 优先级 高于 前缀

建议：不确定时加括号，可读性优于炫技。