Else–if ladder in C - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of an else-if ladder with multiple conditions

What is the output of the following C code?

C

#include <stdio.h>

int main() {
    int x = 15;
    if (x < 10) {
        printf("Less than 10\n");
    } else if (x < 20) {
        printf("Between 10 and 19\n");
    } else if (x < 30) {
        printf("Between 20 and 29\n");
    } else {
        printf("30 or more\n");
    }
    return 0;
}

A Less than 10

B Between 20 and 29

C Between 10 and 19

D 30 or more

💡 Hint

Check which condition matches first in the else-if ladder.

The variable x is 15, which is not less than 10, so the first if fails. The second condition checks if x < 20, which is true, so it prints "Between 10 and 19" and skips the rest.

❓ Predict Output

intermediate

Output when all else-if conditions fail

What will this C program print?

C

#include <stdio.h>

int main() {
    int num = 50;
    if (num < 10) {
        printf("Small number\n");
    } else if (num < 20) {
        printf("Medium number\n");
    } else if (num < 30) {
        printf("Large number\n");
    } else {
        printf("Extra large number\n");
    }
    return 0;
}

A Extra large number

B Medium number

C Large number

D Small number

💡 Hint

Check which condition matches the value 50.

The value 50 does not satisfy any of the first three conditions, so the else block runs and prints "Extra large number".

🔧 Debug

advanced

Identify the error in else-if ladder syntax

What error does this C code produce when compiled?

C

#include <stdio.h>

int main() {
    int a = 5;
    if (a > 0) {
        printf("Positive\n");
    } else if a == 0 {
        printf("Zero\n");
    } else {
        printf("Negative\n");
    }
    return 0;
}

A Runtime error: segmentation fault

B TypeError: invalid comparison

C No error, prints 'Zero'

D SyntaxError: missing parentheses in else-if condition

💡 Hint

Check the syntax of the else-if condition.

In C, the condition in else-if must be enclosed in parentheses. The code 'else if a == 0' is missing parentheses, causing a syntax error.

❓ Predict Output

advanced

Output of nested else-if ladder with multiple variables

What is the output of this C program?

C

#include <stdio.h>

int main() {
    int x = 8, y = 12;
    if (x > 10) {
        if (y > 10) {
            printf("x > 10 and y > 10\n");
        } else {
            printf("x > 10 and y <= 10\n");
        }
    } else if (x > 5) {
        printf("x between 6 and 10\n");
    } else {
        printf("x 5 or less\n");
    }
    return 0;
}

A x > 10 and y > 10

B x between 6 and 10

C x > 10 and y <= 10

D x 5 or less

💡 Hint

Check the first condition and then the else-if condition carefully.

x is 8, which is not greater than 10, so the first if block is skipped. The else-if checks if x > 5, which is true, so it prints "x between 6 and 10".

🧠 Conceptual

expert

Number of times conditions are evaluated in else-if ladder

Consider this else-if ladder in C:

if (cond1) {
    // block1
} else if (cond2) {
    // block2
} else if (cond3) {
    // block3
} else {
    // block4
}

If cond1 is false, cond2 is true, and cond3 is true, how many conditions are evaluated before executing a block?

A 2 conditions

B 1 condition

C 3 conditions

D 4 conditions

💡 Hint

Remember else-if stops checking after the first true condition.

The program checks cond1 (false), then cond2 (true). Since cond2 is true, it executes block2 and stops. So only 2 conditions are evaluated.