4. Operators & Precedence

Operators in C

An operator is a symbol that tells the compiler to perform specific mathematical or logical functions.

1. Arithmetic Operators

Used for mathematical calculations.

• + (Addition)
• - (Subtraction)
• * (Multiplication)
• / (Division - Returns quotient)
• % (Modulus - Returns remainder of integer division)

Example:

int a = 10, b = 3;
printf("Div: %d, Modulo: %d", a/b, a%b); // Div: 3, Modulo: 1

2. Relational Operators

Used to compare two values. They return 1 if true and 0 if false.

• == (Equal to)
• != (Not equal to)
• > (Greater than)
• < (Less than)
• >= (Greater than or equal to)
• <= (Less than or equal to)

Example: 5 > 3 returns 1.

3. Logical Operators

Used to combine conditional statements. Returns 1 (true) or 0 (false).

• && (Logical AND): True if BOTH conditions are true.
• || (Logical OR): True if AT LEAST ONE condition is true.
• ! (Logical NOT): Reverses the logical state (True becomes False).

Example: ((5 > 3) && (10 < 20)) returns 1.

4. Assignment & Shorthand Operators

Used to assign values to variables.

• = (Simple assignment)
• Shorthand Operators (Compound Assignment): Combine an arithmetic/bitwise operator with assignment.
  • a += b is equivalent to a = a + b
  • a -= b is equivalent to a = a - b
  • a *= b is equivalent to a = a * b
  • a /= b is equivalent to a = a / b
  • a %= b is equivalent to a = a % b

5. Increment and Decrement Operators

Used to increase (++) or decrease (--) a value by 1.

• Prefix (e.g., ++a): Increment/decrement happens FIRST, then the new value is used in the expression.
• Postfix (e.g., a++): The current value is used in the expression FIRST, then the increment/decrement happens.

Example:

int x = 5, y = 5;
int p = ++x; // Prefix: x becomes 6, then p is assigned 6. Result: x=6, p=6.
int q = y++; // Postfix: q is assigned 5, then y becomes 6. Result: y=6, q=5.

6. Ternary Operator (Conditional Operator)

A shorthand for if-else. It takes three operands. Syntax: condition ? expression_if_true : expression_if_false;

Example:

int a = 10, b = 20;
int max = (a > b) ? a : b; // max will be 20

7. Bitwise Operators

Operate on bits and perform bit-by-bit operations. Works only with integers.

• & (Bitwise AND): 1 if both bits are 1.
• | (Bitwise OR): 1 if at least one bit is 1.
• ^ (Bitwise XOR): 1 if bits are different.
• ~ (Bitwise NOT/Complement): Flips bits (1s complement).
• << (Left Shift): Shifts bits left (equivalent to multiplying by 2^n).
• >> (Right Shift): Shifts bits right (equivalent to dividing by 2^n).

Example:

int a = 5;  // Binary: 0101
int b = 3;  // Binary: 0011
printf("%d", a & b); // 0001 (Decimal 1)
printf("%d", a | b); // 0111 (Decimal 7)
printf("%d", a << 1); // 1010 (Decimal 10)

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Operator Precedence

Precedence decides which operator evaluates first in an expression. Associativity decides the order (Left-to-Right or Right-to-Left) when operators of the same precedence appear.

Basic Hierarchy (Highest to Lowest):

1. ( ) [ ] (Brackets)
2. ++ -- ! ~ & * sizeof (Unary operators) -> Right to Left
3. * / % (Multiplication / Division / Modulus) -> Left to Right
4. + - (Addition / Subtraction) -> Left to Right
5. << >> (Bitwise Shifts)
6. < <= > >= (Relational)
7. == != (Equality)
8. & (Bitwise AND)
9. ^ (Bitwise XOR)
10. | (Bitwise OR)
11. && (Logical AND)
12. || (Logical OR)
13. ? : (Ternary) -> Right to Left
14. = += -= *= /= %= (Assignment) -> Right to Left

Tip: Use parentheses () to force a specific order of evaluation and ignore default precedence.