Gateway Classes: Unit One-Shot Lecture on Unit Two

Syllabus

Arithmetic Expressions
Operator Precedence
Conditional Branching

Operators

Definition

Operator: A symbol that instructs the compiler to perform specific mathematical or logical manipulations.
Operand: The item on which the operation is performed.
Example: In A + B, A and B are operands, and + is the operator.

Types of Operators

Arithmetic Operators
- + (addition)
- - (subtraction)
- * (multiplication)
- / (division)
- % (modulus)
Relational Operators
- < (less than)
- <= (less than or equal to)
- > (greater than)
- >= (greater than or equal to)
- == (equal to)
- != (not equal to)
Logical Operators
- && (logical AND)
- || (logical OR)
- ! (logical NOT)
Bitwise Operators
- & (bitwise AND)
- | (bitwise OR)
- ^ (bitwise XOR)
- ~ (bitwise NOT)
- << (left shift)
- >> (right shift)
Assignment Operators
- =
- +=, -=, *=, /=, %=, <<=, >>=, &=, ^=, |=
Increment and Decrement Operators
- ++ (increment)
- -- (decrement)
Conditional (Ternary) Operator
- ? :
Comma Operator
- ,
Sizeof Operator
- sizeof

Unary, Binary, and Ternary Operators

Unary Operators
- Requires one operand.
- Examples: ++A, --B
Binary Operators
- Requires two operands.
- Examples: A + B, A - B
Ternary Operators
- Requires three operands.
- Example: condition ? expr1 : expr2

Precedence and Associativity

Precedence determines which operators are evaluated first in an expression.
Associativity determines the direction of evaluation (left-to-right or right-to-left) of operators with the same precedence.

Examples

* has higher precedence than +, so in A + B * C, B * C is evaluated first.
For operators like + and - with the same precedence, associativity is left-to-right, so in A - B + C, A - B is evaluated first.*

Type Conversion

Implicit Conversion (Type Promotion)
- Done by the compiler automatically.
- Example: mixing int and float in an expression results in the int being converted to float.
Explicit Conversion (Type Casting)
- Done by the programmer.
- Syntax: (type) value
- Example: (int) 3.14

Control Statements

Branching
- if
- if-else
- if-else-if
- switch
Looping
- while
- do-while
- for
Jumping
- break
- continue
- goto

Example: Swapping Two Numbers Without Temporary Variable

#include <stdio.h>

int main() {
    int a = 5, b = 3;
    a = a + b; // a = 8
    b = a - b; // b = 5
    a = a - b; // a = 3
    printf("a = %d, b = %d", a, b);
    return 0;
}

Example: Checking Even or Odd Number

int main() {
    int num;
    printf("Enter a number: ");
    scanf("%d", &num);
    if (num % 2 == 0)
        printf("%d is even", num);
    else
        printf("%d is odd", num);
    return 0;
}

Quadratic Equation Roots

Formula: ax² + bx + c = 0
Discriminant: D = b² - 4ac
Nature of Roots
- D > 0: real and distinct
- D = 0: real and equal
- D < 0: imaginary

Example: Finding Roots of a Quadratic Equation

#include <math.h>
#include <stdio.h>

int main() {
    double a, b, c, discriminant, root1, root2;
    printf("Enter coefficients a, b, and c: ");
    scanf("%lf %lf %lf", &a, &b, &c);
    discriminant = b * b - 4 * a * c;
    if (discriminant > 0) {
        root1 = (-b + sqrt(discriminant)) / (2 * a);
        root2 = (-b - sqrt(discriminant)) / (2 * a);
        printf("Roots are real and distinct: %.2lf, %.2lf", root1, root2);
    } else if (discriminant == 0) {
        root1 = root2 = -b / (2 * a);
        printf("Roots are real and equal: %.2lf, %.2lf", root1, root2);
    } else {
        printf("Roots are imaginary");
    }
    return 0;
}

Character Type Check

Example: Check for Vowel or Consonant

#include <stdio.h>

int main() {
    char c;
    printf("Enter a character: ");
    scanf(" %c", &c);
    switch (c) {
        case 'a':
        case 'e':
        case 'i':
        case 'o':
        case 'u':
        case 'A':
        case 'E':
        case 'I':
        case 'O':
        case 'U':
            printf("%c is a vowel", c);
            break;
        default:
            printf("%c is a consonant", c);
    }
    return 0;
}

Difference Between Switch and If-Else Statements

Switch
- Syntax: switch(expression) { case value1: statements; break; ... default: ; }
- Fast operation: Directly jumps to matching case.
- Handles only integral types.
- Requires break statements.
- Case labels must be unique and constant.
If-Else
- Syntax: if (condition) { statements } else { }
- Slow operation: Sequential evaluation of conditions.
- Handles various data types.
- Does not require break statements.