Introduction to Programming in C

📘 Conditional Statements in C

Conditional statements allow your C programs to make decisions during execution. They evaluate expressions and execute code blocks depending on whether the conditions are true or false. These are essential for flow control and implementing logic.

🔹 Types of Conditional Statements

• if statement
• if...else statement
• if...else if...else ladder
• nested if statements
• switch statement

🟢 The if Statement

Executes a block of code if a specified condition is true.

int age = 20;
if (age >= 18) {
    printf("You are eligible to vote.\n");
}

🟠 The if...else Statement

Executes one block if the condition is true, another if it's false.

int num = 7;
if (num % 2 == 0) {
    printf("Even number\n");
} else {
    printf("Odd number\n");
}

🟡 The if...else if...else Ladder

Used when you need to check multiple conditions in a sequence.

int marks = 85;
if (marks >= 90) {
    printf("Grade A\n");
} else if (marks >= 75) {
    printf("Grade B\n");
} else if (marks >= 60) {
    printf("Grade C\n");
} else {
    printf("Grade D\n");
}

🔵 Nested if Statements

An if block inside another if block. Used for complex decision trees.

int age = 25;
int hasID = 1;
if (age >= 18) {
    if (hasID == 1) {
        printf("Entry allowed.\n");
    } else {
        printf("Please bring your ID.\n");
    }
}

🔘 The switch Statement

Used when you have multiple specific values to compare against a single variable.

int day = 3;
switch (day) {
    case 1:
        printf("Monday\n");
        break;
    case 2:
        printf("Tuesday\n");
        break;
    case 3:
        printf("Wednesday\n");
        break;
    default:
        printf("Invalid day\n");
}

📝 Comparison: if-else vs switch

💡 Real-Life Example (UdaanPath)

int userChoice = 2;
switch (userChoice) {
    case 1:
        printf("Show SSC Preparation Materials\n");
        break;
    case 2:
        printf("Show IT Fundamentals Course\n");
        break;
    default:
        printf("Browse All Courses on UdaanPath\n");
}

🧪 Practice Tasks

1. Write a program to take age as input and check if the person is a minor, adult, or senior citizen.
2. Use a switch-case to build a basic calculator (Add, Subtract, Multiply, Divide).
3. Build a grading system based on percentage using if-else ladder.
4. Check if a number is positive, negative, or zero using nested if.

📚 Summary

• Conditional statements are used to make decisions in programs.
• if, else, and switch help execute code blocks conditionally.
• switch is best for fixed constant checks; if is flexible for ranges and logic.

✅ Coming Next

In the next chapter, we will explore Loops in C – understanding for, while, and do-while to perform repetitive tasks efficiently.