C++之赋值、比较、逻辑运算符

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：

 1 int main() {
 2 
 3     //赋值运算符
 4 
 5     // =
 6     int a = 10;
 7     a = 100;
 8     cout << "a = " << a << endl;
 9 
10     // +=
11     a = 10;
12     a += 2; // a = a + 2;
13     cout << "a = " << a << endl;
14 
15     // -=
16     a = 10;
17     a -= 2; // a = a - 2
18     cout << "a = " << a << endl;
19 
20     // *=
21     a = 10;
22     a *= 2; // a = a * 2
23     cout << "a = " << a << endl;
24 
25     // /=
26     a = 10;
27     a /= 2;  // a = a / 2;
28     cout << "a = " << a << endl;
29 
30     // %=
31     a = 10;
32     a %= 2;  // a = a % 2;
33     cout << "a = " << a << endl;
34 
35     system("pause");
36 
37     return 0;
38 }

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：

 1 int main() {
 2 
 3     int a = 10;
 4     int b = 20;
 5 
 6     cout << (a == b) << endl; // 0 
 7 
 8     cout << (a != b) << endl; // 1
 9 
10     cout << (a > b) << endl; // 0
11 
12     cout << (a < b) << endl; // 1
13 
14     cout << (a >= b) << endl; // 0
15 
16     cout << (a <= b) << endl; // 1
17     
18     system("pause");
19 
20     return 0;
21 }

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：

 1 //逻辑运算符  --- 非
 2 int main() {
 3 
 4     int a = 10;
 5 
 6     cout << !a << endl; // 0
 7 
 8     cout << !!a << endl; // 1
 9 
10     system("pause");
11 
12     return 0;
13 }

 1 //逻辑运算符  --- 与
 2 int main() {
 3 
 4     int a = 10;
 5     int b = 10;
 6 
 7     cout << (a && b) << endl;// 1
 8 
 9     a = 10;
10     b = 0;
11 
12     cout << (a && b) << endl;// 0 
13 
14     a = 0;
15     b = 0;
16 
17     cout << (a && b) << endl;// 0
18 
19     system("pause");
20 
21     return 0;
22 }

 1 //逻辑运算符  --- 或
 2 int main() {
 3 
 4     int a = 10;
 5     int b = 10;
 6 
 7     cout << (a || b) << endl;// 1
 8 
 9     a = 10;
10     b = 0;
11 
12     cout << (a || b) << endl;// 1 
13 
14     a = 0;
15     b = 0;
16 
17     cout << (a || b) << endl;// 0
18 
19     system("pause");
20 
21     return 0;
22 }