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Conditional statements are a fundamental concept in programming that allows you to make decisions based on certain conditions. These statements enable your code to execute different blocks of code depending on whether specific conditions are met or not. In this blog post, we’ll delve into the basics of conditional statements, starting with the ubiquitous if-else statement and gradually exploring more complex scenarios.

The `if-else` Statement

‘if statement’ is used to execute a block of code only if a certain condition is met. It allows us to conditionally execute code based on whether the specified condition is true.

‘else statement’, on the other hand, is an optional companion to the if statement. It specifies what code to execute if the condition in the if statement is not met (i.e. if it is false).

Let’s break down the flow of control:

• If the test condition in the if statement is true, a block of code inside the if block will be executed.
• If the test condition is false, the code inside the else block (if present) will be executed.

Code:

#include<bits/stdc++.h>
using namespace std;

int main() {
int age=10;


if (age >= 18) {
    cout << "You are an adult." << endl;
} else {
    cout << "You are not an adult." << endl;
}

}

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        int age=10;
       

        if (age >= 18) {
            System.out.println("You are an adult.");
        } else {
            System.out.println("You are not an adult.");
        }

        scanner.close();
    }
}

In this example, we take the user’s age as input and use an if statement to check if the age is greater than or equal to 18. If the condition is true, it prints “You are an adult,” and if it’s false ie. the ‘else’ condition is satisfied, it prints “You are not an adult.”

Simplifying Code with “else if”

As your code becomes more complex, you’ll often encounter scenarios where you need to check multiple conditions. Instead of writing multiple independent if statements, you can streamline your code using else if statements.

Let’s say we want to grade students based on their marks within specific ranges:

Code:

#include <iostream>
using namespace std;

int main() {
    int marks = 54;


    if (marks < 25) {
        cout << "Grade: F" << endl;
    } else if (marks >= 25 && marks <= 44) {
        cout << "Grade: E" << endl;
    } else if (marks >= 45 && marks <= 49) {
        cout << "Grade: D" << endl;
    } else if (marks >= 50 && marks <= 59) {
        cout << "Grade: C" << endl;
    } else if (marks >= 60 && marks <= 69) {
        cout << "Grade: B" << endl;
    } else if (marks >= 70) {
        cout << "Grade: A" << endl;
    } else {
        cout << "Invalid marks entered." << endl;
    }

    return 0;
}

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        int marks = 54;


        if (marks < 25) {
            System.out.println("Grade: F");
        } else if (marks >= 25 && marks <= 44) {
            System.out.println("Grade: E");
        } else if (marks >= 45 && marks <= 49) {
            System.out.println("Grade: D");
        } else if (marks >= 50 && marks <= 59) {
            System.out.println("Grade: C");
        } else if (marks >= 60 && marks <= 69) {
            System.out.println("Grade: B");
        } else if (marks >= 70) {
            System.out.println("Grade: A");
        } else {
            System.out.println("Invalid marks entered.");
        }
        scanner.close();
    }
}

• If marks are less than 25, it prints “Grade: F.”
• If marks are between 25 and 44 (inclusive), it prints “Grade: E.”
• If marks are between 45 and 49 (inclusive), it prints “Grade: D.”
• If marks are between 50 and 59 (inclusive), it prints “Grade: C.”
• If marks are between 60 and 69 (inclusive), it prints “Grade: B.”
• If marks are 70 or higher, it prints “Grade: A.”
• If marks are outside the valid range, it prints “Invalid marks entered.”

The provided code for grading based on marks is functional, but it can be simplified for better readability and maintainability. In the current code, there are several redundant comparisons of marks with specific values. For example, when checking for grades E, C, B, and A, you have to repeatedly check marks >= X && marks <= Y, which can be error-prone and hard to maintain as the grade ranges change.

We can refactor the code, we can remove the lower bounds and check only the upper bounds for each grade as the code flow is such that we move along the conditions only after satisfying the previous one.

Code:

#include <iostream>

int main() {
    int marks = 54;
    char grade;

    if (marks < 25) {
        grade = 'F';
    } else if (marks <= 44) {
        grade = 'E';
    } else if (marks <= 49) {
        grade = 'D';
    } else if (marks <= 59) {
        grade = 'C';
    } else if (marks <= 69) {
        grade = 'B';
    } else if (marks >= 70) {
        grade = 'A';
    } else {
        grade = 'X'; // Use 'X' to indicate invalid marks
    }

    std::cout << "Grade: " << grade << std::endl;
    
    return 0;
}

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        int marks=54;


        char grade;

        if (marks < 25) {
            grade = 'F';
        } else if (marks <= 44) {
            grade = 'E';
        } else if (marks <= 49) {
            grade = 'D';
        } else if (marks <= 59) {
            grade = 'C';
        } else if (marks <= 69) {
            grade = 'B';
        } else if (marks >= 70) {
            grade = 'A';
        } else {
            grade = 'X'; // Use 'X' to indicate invalid marks
        }

        System.out.println("Grade: " + grade);
        scanner.close();
    }
}

Conditional statements are indispensable tools for controlling the flow of your program. Whether you’re making simple decisions or handling complex logic, if-else statements and their variants empower you to write code that responds dynamically to changing conditions. Mastering these fundamentals is essential for any aspiring programmer.

Special thanks to Gauri Tomar for contributing to this article on takeUforward. If you also wish to share your knowledge with the takeUforward fam, please check out this article