If & else Statements in C++

Conditional statements like if and else are fundamental to controlling the flow of a program. They allow you to execute specific blocks of code based on certain conditions. In this blog, we will explore the if and else statements in C++, their usage, and provide examples to help you understand how to work with them effectively.

1. Introduction to Conditional Statements

Conditional statements are used to perform different actions based on different conditions. In C++, the most common conditional statements are:

• if statement
• else statement
• else if statement
• Nested if statements

 

2. The if Statement

The if statement executes a block of code if a specified condition is true.

Syntax

if (condition) {

    // Code to be executed if condition is true

}

Example

#include <iostream>

int main() {

    int number = 10;

    if (number > 5) {

        std::cout << "The number is greater than 5." << std::endl;

    }

    return 0;

}

In this example:

• The if statement checks if the variable number is greater than 5. If true, it prints "The number is greater than 5."

 

3. The else Statement

The else statement executes a block of code if the condition in the if statement is false.

Syntax

if (condition) {

    // Code to be executed if condition is true

} else {

    // Code to be executed if condition is false

}

Example

#include <iostream>

int main() {

    int number = 3;

    if (number > 5) {

        std::cout << "The number is greater than 5." << std::endl;

    } else {

        std::cout << "The number is not greater than 5." << std::endl;

    }

    return 0;

}

In this example:

• If number is greater than 5, it prints "The number is greater than 5."
• Otherwise, it prints "The number is not greater than 5."

 

4. The else if Statement

The else if statement specifies a new condition to test if the previous condition(s) were false.

Syntax

if (condition1) {

    // Code to be executed if condition1 is true

} else if (condition2) {

    // Code to be executed if condition2 is true

} else {

    // Code to be executed if all conditions are false

}

Example

#include <iostream>

int main() {

    int number = 7;

    if (number > 10) {

        std::cout << "The number is greater than 10." << std::endl;

    } else if (number > 5) {

        std::cout << "The number is greater than 5 but not greater than 10." << std::endl;

    } else {

        std::cout << "The number is 5 or less." << std::endl;

    }

    return 0;

}

In this example:

• The program first checks if number is greater than 10.
• If not, it checks if number is greater than 5.
• If both conditions are false, it executes the else block.

 

5. Nested if Statements

Nested if statements are if statements inside another if statement. They allow you to check multiple conditions in a hierarchical manner.

Syntax

if (condition1) {

    // Code to be executed if condition1 is true

    if (condition2) {

        // Code to be executed if condition2 is true

    }

}

Example

#include <iostream>

int main() {

    int number = 15;

    if (number > 10) {

        std::cout << "The number is greater than 10." << std::endl;

        if (number % 2 == 0) {

            std::cout << "The number is even." << std::endl;

        } else {

            std::cout << "The number is odd." << std::endl;

        }

    }

    return 0;

}

In this example:

• The outer if statement checks if number is greater than 10.
• If true, the inner if statement checks if number is even or odd.

 

6. Best Practices for Using Conditional Statements

1. Keep It Simple: Avoid deeply nested if statements as they can make the code harder to read and maintain.
2. Use Meaningful Conditions: Ensure that your conditions are clear and meaningful.
3. Combine Conditions When Appropriate: Use logical operators to combine conditions when it makes sense to simplify your code.
4. Consider Edge Cases: Make sure your conditions handle all possible input scenarios, including edge cases.

 

Example: Best Practices

#include <iostream>

int main() {

    int age = 20;

    if (age >= 18) {

        std::cout << "You are eligible to vote." << std::endl;

        if (age >= 21) {

            std::cout << "You are also eligible to drink alcohol." << std::endl;

        } else {

            std::cout << "You are not eligible to drink alcohol." << std::endl;

        }

    } else {

        std::cout << "You are not eligible to vote." << std::endl;

    }

    return 0;

}

In this example:

• The outer if statement checks if age is 18 or older.
• The inner if statement further checks if age is 21 or older.

 

Final Remarks

Mastering if and else statements in C++ is crucial for writing effective and efficient programs. By understanding how to use these conditional statements, you can control the flow of your program based on different conditions. Remember to follow best practices to write clear and maintainable code.

Stay tuned for more in-depth explorations of C++ features and advanced programming techniques.