Conditional Statement

Index

Conditional Statement

A conditional statement in C is used to make decisions in your program. It lets you execute certain parts of your code only if a specific condition is true or false.

There are three main types of conditional statements in C:

if statement
if-else statement
else if ladder

if Statement

The if statement evaluates a condition, and if that condition is true, it executes the block of code inside the if statement. If the condition is false, the code block is skipped.

Syntax:

if (condition) {
    // Code to be executed if the condition is true
}

Example:

#include <stdio.h>

int main() {
    int x = 10;

    if (x > 5) {
        printf("x is greater than 5\n");
    }

    return 0;
}

Output

x is greater than 5

Explanation:
- The condition x > 5 is true because x is 10. So, the program will print x is greater than 5.

if-else Statement

else if: Provides an additional condition if the previous if (or else if) was false..

Syntax:

if (condition) {
    // Code to be executed if the condition is true
} else {
    // Code to be executed if the condition is false
}

Example:

#include <stdio.h>

int main() {
    int x = 3;

    if (x > 5) {
        printf("x is greater than 5\n");
    } else {
        printf("x is less than or equal to 5\n");
    }

    return 0;
}

Output

x is less than or equal to 5

Explanation:
- The condition x > 5 is false because x is 3, so the else block will execute, printing x is less than or equal to 5.

else if Ladder

The else if ladder allows you to check multiple conditions sequentially. It executes the first block of code where the condition is true and skips the rest. If none of the conditions are true, it executes the else block.

Syntax:

if (condition1) {
    // Code if condition1 is true
} else if (condition2) {
    // Code if condition2 is true
} else {
    // Code if all conditions are false
}

Example:

#include <stdio.h>

int main() {
    int x = 10;

    if (x > 15) {
        printf("x is greater than 15\n");
    } else if (x == 10) {
        printf("x is equal to 10\n");
    } else {
        printf("x is less than 10\n");
    }

    return 0;
}

Output

x is equal to 10

Explanation:
- The condition x > 15 is false, but x == 10 is true, so the program will print x is equal to 10. It does not check further once a true condition is found.

Here’s a C program that demonstrates all types of conditional statements (if, if-else, else if, and the ternary operator) in a real-world example. Let’s imagine a simple restaurant order system that checks the user’s age and preferences to offer different menu options and discounts.

Restaurant Menu Code

In this program:

We check the user’s age to apply a discount if they’re a child, adult, or senior.
We take the user’s preference (vegetarian or non-vegetarian) to suggest a menu item.
Finally, we use the ternary operator to add a message about the special of the day.

#include <stdio.h>

int main() {
    int age;
    char preference;
    int discount;
    char* menuItem;

    printf("Welcome to the Restaurant!\n");
    printf("Please enter your age: ");
    scanf("%d", &age);

    // Applying age-based discounts
    if (age <= 12) {
        discount = 50;  // 50% discount for children
        printf("You're eligible for a 50%% discount!\n");
    } else if (age >= 60) {
        discount = 30;  // 30% discount for seniors
        printf("You're eligible for a 30%% discount!\n");
    } else {
        discount = 10;  // 10% discount for all other adults
        printf("You're eligible for a 10%% discount!\n");
    }

    // Taking preference input
    printf("Do you prefer (v)egetarian or (n)on-vegetarian? ");
    scanf(" %c", &preference);  // Added a space to ignore any leading newline character

    // Suggesting a menu item based on preference
    if (preference == 'v' || preference == 'V') {
        menuItem = "Grilled Veggie Platter";
    } else if (preference == 'n' || preference == 'N') {
        menuItem = "Grilled Chicken with Herbs";
    } else {
        printf("Invalid choice! Defaulting to a vegetarian menu.\n");
        menuItem = "Mixed Veg Salad";
    }

    // Displaying the final order details
    printf("\nThank you for your order!\n");
    printf("Your menu item: %s\n", menuItem);
    printf("Discount applied: %d%%\n", discount);

    // Ternary operator to display a message about the special of the day
    char* specialMessage = (age <= 25) ? "You get a free dessert today!" : "Enjoy our special soup with your meal!";
    printf("%s\n", specialMessage);

    return 0;
}

Explanation

If-Else Statements:
- We first use if-else to check the user’s age and apply a discount.
- The first if checks if the age is less than or equal to 12, applying a 50% discount.
- The else if checks if the age is 60 or older for a 30% discount.
- If neither condition is met, the else applies a 10% discount.
Nested If Statements:
- After gathering the user’s age, we ask for their meal preference (vegetarian or non-vegetarian).
- We use if statements to assign a menu item based on their choice, using || (logical OR) to accept both uppercase and lowercase inputs for v and n.
- If an invalid input is given, we default to a vegetarian option.
Ternary Operator:
- The ternary operator is used to display a special message based on the user’s age.
- If the age is less than or equal to 25, the user receives a free dessert, otherwise a complimentary soup.

Output Example

For a sample user, the output might look like this:

Welcome to the Restaurant!
Please enter your age: 27
You're eligible for a 10% discount!
Do you prefer (v)egetarian or (n)on-vegetarian? n

Thank you for your order!
Your menu item: Grilled Chicken with Herbs
Discount applied: 10%
Enjoy our special soup with your meal!

Conditional Statement