Expressions&Operators 表达式与运算符

Expressions

Expressions are combinations of variables, constants, and operators that produce a single value. - Expressions produce values

Operators

Operators are special symbols that perform operations on operands(操作数) (variables, constants).

Basic Operator Types

1. Arithmetic Operators 算术运算符

int a = 10, b = 3;
a + b   // 13  (Addition)
a - b   // 7   (Subtraction)  
a * b   // 30  (Multiplication)
a / b   // 3   (Division - integer)
a % b   // 1   (Modulo - remainder)

2. Relational Operators 关系运算符

a == b  // 0 (Equal to)
a != b  // 1 (Not equal to)
a > b   // 1 (Greater than)
a < b   // 0 (Less than)
a >= b  // 1 (Greater than or equal to)
a <= b  // 0 (Less than or equal to)

3. Logical Operators 逻辑运算符

int x = 5, y = 10;
(x > 0) && (y < 20)  // 1 (AND - both must be true)
(x > 10) || (y == 10) // 1 (OR - at least one true)
!(x == 5)             // 0 (NOT - reverses truth)

4. Assignment Operators 赋值运算符

int num = 10;
num += 5;   // num = num + 5  → 15
num -= 3;   // num = num - 3  → 12
num *= 2;   // num = num * 2  → 24
num /= 4;   // num = num / 4  → 6

5. Increment/Decrement Operators 自增/自减运算符

int count = 5;
count++;    // Post-increment: use then increase → 5 (then count becomes 6)
++count;    // Pre-increment: increase then use → 7 (count becomes 7)
count--;    // Post-decrement → 7 (then becomes 6)
--count;    // Pre-decrement → 5 (count becomes 5)

6. Conditional (Ternary) Operator 条件（三元）运算符

int age = 20;
char* status = (age >= 18) ? "Adult" : "Minor";
// If age >= 18, status = "Adult", else "Minor"

7. Comma Operator 逗号运算符

int a, b, c;
a = (b = 5, c = 10, b + c);  // a = 15, b = 5, c = 10