Operators and Expressions

1. Types of Operators

C has a rich set of operators categorized by what they do.

A. Arithmetic Operators

Used for mathematical calculations.

| Operator | Description | Example ($a=10, b=3$) | Result |

| :--- | :--- | :--- | :--- |

| + | Addition | a + b | 13 |

| - | Subtraction | a - b | 7 |

| * | Multiplication | a * b | 30 |

| / | Division | a / b | 3 (Integer division) |

| % | Modulus | a % b | 1 (Remainder) |

B. Relational & Logical Operators

Used for decision-making (True/False). In C, 0 is False and any non-zero value is True.

• Relational: == (equal to), != (not equal), >, <, >=, <=

• Logical: && (AND), || (OR), ! (NOT)

C. Increment and Decrement

• ++x: Pre-increment (Add 1, then use).

• x++: Post-increment (Use, then add 1).1. Types of Operators

  C has a rich set of operators categorized by what they do.

  A. Arithmetic Operators

  Used for mathematical calculations.

  | Operator | Description | Example ($a=10, b=3$) | Result |

  | :--- | :--- | :--- | :--- |

  | + | Addition | a + b | 13 |

  | - | Subtraction | a - b | 7 |

  | * | Multiplication | a * b | 30 |

  | / | Division | a / b | 3 (Integer division) |

  | % | Modulus | a % b | 1 (Remainder) |

  B. Relational & Logical Operators

  Used for decision-making (True/False). In C, 0 is False and any non-zero value is True.

  • Relational: == (equal to), != (not equal), >, <, >=, <=

  • Logical: && (AND), || (OR), ! (NOT)

  C. Increment and Decrement

• ++x: Pre-increment (Add 1, then use).

#include <stdio.h>

int main() {
    int a = 10, b = 4;
    int result;

    // Arithmetic expression
    result = a * b + 2; // (10 * 4) + 2 = 42
    printf("Result 1: %d\n", result);

    // Using Modulus (Remainder)
    int remainder = a % b; // 10 divided by 4 leaves 2
    printf("Remainder: %d\n", remainder);

    // Logical expression
    // Is 'a' greater than 5 AND 'b' less than 10?
    if (a > 5 && b < 10) {
        printf("Both conditions are true!\n");
    }

    // Increment
    int x = 5;
    printf("Post-increment: %d\n", x++); // Prints 5, then becomes 6
    printf("Value now: %d\n", x);

    return 0;
}

Expected Output:

Result 1: 42
Remainder: 2
Both conditions are true!
Post-increment: 5
Value now: 6

3. Type Casting in Expressions

Sometimes you need to change a data type temporarily to get the right result in an expression. This is called Type Casting.

int total = 10, count = 4;
float average;

// Without casting: 10 / 4 = 2.0 (because both are ints)
// With casting: (float)10 / 4 = 2.5
average = (float)total / count;

Expected Output:

Bad Average: 2.0
Good Average: 2.5

Key Tip: Assignment is an Operator

In C, = is an operator that returns a value. This is why you can do: x = y = z = 100; It assigns 100 to z, then that result to y, then that result to x.