else-if Ladder in C

An else-if ladder allows you to test several conditions one after another. It is useful when there are more than two possible outcomes.

if (condition1)
{
    // statement
}
else if (condition2)
{
    // statement
}
else if (condition3)
{
    // statement
}
else
{
    // default statement
}

if (condition1)
{
    statement1;
}
else if (condition2)
{
    statement2;
}
else
{
    statement3;
}

The program first checks condition1. If it is false, it checks condition2. If all conditions are false, the else block executes.

int number = 0;

if (number > 0)
{
    printf("Positive");
}
else if (number < 0)
{
    printf("Negative");
}
else
{
    printf("Zero");
}

The program checks three possible cases: positive, negative, and zero.

The execution takes place from top to bottom:

1. The first if condition is checked.
2. If it is true, its block executes.
3. If it is false, the next else if condition is checked.
4. This continues until a true condition is found.
5. If no condition is true, the final else executes.

int marks = 75;

if (marks >= 80)
{
    printf("Grade A");
}
else if (marks >= 60)
{
    printf("Grade B");
}
else if (marks >= 40)
{
    printf("Grade C");
}
else
{
    printf("Fail");
}

Since the marks are 75, the second condition is true and Grade B is displayed.

int marks = 92;

if (marks >= 90)
{
    printf("A+");
}
else if (marks >= 80)
{
    printf("A");
}
else if (marks >= 70)
{
    printf("B");
}
else if (marks >= 60)
{
    printf("C");
}
else if (marks >= 40)
{
    printf("D");
}
else
{
    printf("F");
}

The conditions are checked from the highest range to the lowest range.

int age = 25;

if (age < 13)
{
    printf("Child");
}
else if (age < 20)
{
    printf("Teenager");
}
else if (age < 60)
{
    printf("Adult");
}
else
{
    printf("Senior Citizen");
}

Each condition represents a different age group.

int number;

printf("Enter a number: ");
scanf("%d", &number);

if (number > 0)
{
    printf("Positive");
}
else if (number < 0)
{
    printf("Negative");
}
else
{
    printf("Zero");
}

This is a common beginner example of an else-if ladder.

int a = 30;
int b = 20;
int c = 10;

if (a > b && a > c)
{
    printf("A is largest");
}
else if (b > a && b > c)
{
    printf("B is largest");
}
else
{
    printf("C is largest or there is a tie");
}

Logical operators can be used inside else-if conditions.

int day = 3;

if (day == 1)
{
    printf("Monday");
}
else if (day == 2)
{
    printf("Tuesday");
}
else if (day == 3)
{
    printf("Wednesday");
}
else
{
    printf("Invalid day");
}

Each condition checks a different value.

int marks = 68;

if (marks >= 90)
{
    printf("Excellent");
}
else if (marks >= 75)
{
    printf("Very Good");
}
else if (marks >= 50)
{
    printf("Good");
}
else
{
    printf("Needs Improvement");
}

Only the first matching condition is executed.

#include <stdio.h>

int main()
{
    int marks;

    printf("Enter marks: ");
    scanf("%d", &marks);

    if (marks >= 90)
    {
        printf("Grade A+");
    }
    else if (marks >= 80)
    {
        printf("Grade A");
    }
    else if (marks >= 60)
    {
        printf("Grade B");
    }
    else if (marks >= 40)
    {
        printf("Grade C");
    }
    else
    {
        printf("Fail");
    }

    return 0;
}

int temperature = 35;

if (temperature >= 40)
{
    printf("Very Hot");
}
else if (temperature >= 30)
{
    printf("Hot");
}
else if (temperature >= 20)
{
    printf("Normal");
}
else
{
    printf("Cold");
}

The program classifies the temperature into different ranges.

int salary = 45000;

if (salary >= 100000)
{
    printf("High Salary");
}
else if (salary >= 50000)
{
    printf("Good Salary");
}
else if (salary >= 25000)
{
    printf("Average Salary");
}
else
{
    printf("Low Salary");
}

int number = 15;

if (number % 2 == 0)
{
    printf("Divisible by 2");
}
else if (number % 3 == 0)
{
    printf("Divisible by 3");
}
else if (number % 5 == 0)
{
    printf("Divisible by 5");
}
else
{
    printf("Not divisible by 2, 3 or 5");
}

Remember that the first true condition stops the ladder.

char grade = 'B';

if (grade == 'A')
{
    printf("Excellent");
}
else if (grade == 'B')
{
    printf("Very Good");
}
else if (grade == 'C')
{
    printf("Good");
}
else
{
    printf("Needs Improvement");
}

Character values can be compared using the equality operator.

char operator = '+';
int a = 10;
int b = 5;

if (operator == '+')
{
    printf("%d", a + b);
}
else if (operator == '-')
{
    printf("%d", a - b);
}
else if (operator == '*')
{
    printf("%d", a * b);
}
else if (operator == '/')
{
    printf("%d", a / b);
}
else
{
    printf("Invalid operator");
}

An else-if ladder can select an operation based on the operator entered.

int age = 17;

if (age < 0)
{
    printf("Invalid age");
}
else if (age >= 18)
{
    printf("Eligible to vote");
}
else
{
    printf("Not eligible to vote");
}

The first condition handles invalid input before checking eligibility.

int cost = 1000;
int selling = 1200;

if (selling > cost)
{
    printf("Profit");
}
else if (selling < cost)
{
    printf("Loss");
}
else
{
    printf("No profit and no loss");
}

Three possible outcomes are handled using the ladder.

float percentage = 82.5f;

if (percentage >= 90.0f)
{
    printf("Excellent");
}
else if (percentage >= 75.0f)
{
    printf("Very Good");
}
else if (percentage >= 60.0f)
{
    printf("Good");
}
else
{
    printf("Needs Improvement");
}

Floating-point variables can also be used in an else-if ladder.

int marks = 85;

if (marks >= 40)
{
    printf("Pass");
}
else if (marks >= 80)
{
    printf("Excellent");
}

Here, marks >= 40 is true first, so the second condition is never reached.

For range-based grading, conditions should generally be arranged from the highest threshold to the lowest when that matches the intended logic.

int marks = 72;

if (marks >= 90)
{
    printf("A+");
}
else if (marks >= 80)
{
    printf("A");
}
else if (marks >= 70)
{
    printf("B");
}
else if (marks >= 60)
{
    printf("C");
}
else
{
    printf("Fail");
}

Because the conditions are checked from top to bottom, 72 matches the marks >= 70 condition.

The final else is optional.

int number = 20;

if (number > 100)
{
    printf("Greater than 100");
}
else if (number > 10)
{
    printf("Greater than 10");
}

If no condition is true, nothing inside the ladder executes.

Multiple related alternatives are often easier to read with an else-if ladder.

if (marks >= 80)
{
    printf("A");
}
else if (marks >= 60)
{
    printf("B");
}
else
{
    printf("C");
}

Nested if statements are still useful when a decision depends on another decision.

One common mistake is placing a broad condition before a more specific condition.

if (marks >= 40)
{
    printf("Pass");
}
else if (marks >= 90)
{
    printf("Excellent");
}

The second condition can never be reached for values 90 or higher because those values already satisfy the first condition.

Arrange conditions carefully according to the required logic.

Incorrect:

if (number = 10)
{
    printf("Ten");
}
else if (number = 20)
{
    printf("Twenty");
}

The = operator performs assignment. Use == when you want to compare values.

Correct:

if (number == 10)
{
    printf("Ten");
}
else if (number == 20)
{
    printf("Twenty");
}

#include <stdio.h>

int main()
{
    int marks;

    printf("Enter marks: ");
    scanf("%d", &marks);

    if (marks >= 90)
    {
        printf("Grade A+");
    }
    else if (marks >= 80)
    {
        printf("Grade A");
    }
    else if (marks >= 70)
    {
        printf("Grade B");
    }
    else if (marks >= 60)
    {
        printf("Grade C");
    }
    else if (marks >= 40)
    {
        printf("Grade D");
    }
    else
    {
        printf("Fail");
    }

    return 0;
}

#include <stdio.h>

int main()
{
    int number;

    printf("Enter a number: ");
    scanf("%d", &number);

    if (number > 0)
    {
        printf("Positive");
    }
    else if (number < 0)
    {
        printf("Negative");
    }
    else
    {
        printf("Zero");
    }

    return 0;
}

#include <stdio.h>

int main()
{
    int a, b;
    char op;

    printf("Enter two numbers: ");
    scanf("%d %d", &a, &b);

    printf("Enter operator (+, -, *, /): ");
    scanf(" %c", &op);

    if (op == '+')
    {
        printf("Result = %d", a + b);
    }
    else if (op == '-')
    {
        printf("Result = %d", a - b);
    }
    else if (op == '*')
    {
        printf("Result = %d", a * b);
    }
    else if (op == '/')
    {
        if (b != 0)
        {
            printf("Result = %d", a / b);
        }
        else
        {
            printf("Cannot divide by zero");
        }
    }
    else
    {
        printf("Invalid operator");
    }

    return 0;
}

Practice the following programs:

1. Create a grade calculator.
2. Check whether a number is positive, negative, or zero.
3. Classify a person by age group.
4. Find the largest among three numbers.
5. Find the smallest among three numbers.
6. Create a simple calculator using operators.
7. Check profit, loss, or no profit.
8. Classify temperature into different ranges.
9. Check marks and display a suitable grade.
10. Create a menu-based program using an else-if ladder.

Always check the conditions in the correct order and remember that the first true condition is executed.