Why conditional logic is needed - Challenge Your Understanding

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this C code with conditional logic?

Look at this C program. What will it print when run?

C

#include <stdio.h>

int main() {
    int temperature = 30;
    if (temperature > 25) {
        printf("It's hot today!\n");
    } else {
        printf("It's cool today!\n");
    }
    return 0;
}

A It's hot today!

B It's cool today!

C Compilation error

D No output

💡 Hint

Check the value of temperature and the condition in the if statement.

The variable temperature is 30, which is greater than 25, so the if block runs and prints "It's hot today!".

🧠 Conceptual

intermediate

Why do we need conditional logic in programs?

Which of these best explains why conditional logic is important in programming?

A It automatically fixes errors in the code.

B It makes programs run faster by skipping code.

C It stores data permanently for later use.

D It allows programs to make decisions and choose different actions based on data.

💡 Hint

Think about how a program can behave differently depending on what it sees.

Conditional logic lets a program decide what to do next based on conditions, like checking if a number is big or small.

🔧 Debug

advanced

What error does this C code cause?

Look at this code snippet. What error will it cause when compiled?

C

#include <stdio.h>

int main() {
    int x = 10;
    if x > 5 {
        printf("x is greater than 5\n");
    }
    return 0;
}

A Runtime error: division by zero

B Syntax error: missing parentheses around condition

C No error, prints 'x is greater than 5'

D Syntax error: missing semicolon after if

💡 Hint

Check the syntax of the if statement condition.

In C, the condition in an if statement must be inside parentheses. Missing them causes a syntax error.

❓ Predict Output

advanced

What is the output of nested if-else in this C code?

What will this program print?

C

#include <stdio.h>

int main() {
    int score = 75;
    if (score >= 90) {
        printf("Grade A\n");
    } else if (score >= 70) {
        printf("Grade B\n");
    } else {
        printf("Grade C\n");
    }
    return 0;
}

A Grade B

B Grade A

C Grade C

D No output

💡 Hint

Check which condition matches the value of score.

The score is 75, which is not >= 90 but is >= 70, so it prints "Grade B".

🧠 Conceptual

expert

How does conditional logic improve program flexibility?

Which statement best describes how conditional logic helps programs be flexible?

A It stores user data securely in memory.

B It makes programs run faster by removing unnecessary code.

C It lets programs respond differently to changing inputs or situations.

D It automatically corrects user mistakes without input.

💡 Hint

Think about how programs can change what they do based on what happens.

Conditional logic allows programs to choose different paths, making them adaptable to different inputs or conditions.

Practice

1. Why do we use conditional logic like if statements in C programs?

easy

A. To repeat code multiple times

B. To make decisions based on different conditions

C. To store multiple values in one variable

D. To define new data types

Solution

1. Step 1: Understand the purpose of conditional logic

   Conditional logic allows a program to choose different actions depending on conditions.

2. Step 2: Compare with other options

   Repeating code is done with loops, storing values uses arrays or variables, and defining types uses structs or typedefs.

3. Final Answer:

   To make decisions based on different conditions -> Option B

4. Quick Check:

   Conditional logic = decision making [OK]

Hint: If you want choices, use if-else [OK]

Common Mistakes:

• Confusing loops with conditionals
• Thinking variables store multiple values
• Mixing data types with logic

2. Which of the following is the correct syntax for an if statement in C?

easy

A. if (condition) { /* code */ }

B. if condition { /* code */ }

C. if condition then { /* code */ }

D. if [condition] { /* code */ }

Solution

1. Step 1: Recall C syntax for if statements

   In C, conditions must be inside parentheses and code inside braces.

2. Step 2: Check each option

   if (condition) { /* code */ } matches the correct syntax: if (condition) { /* code */ }.

3. Final Answer:

   if (condition) { /* code */ } -> Option A

4. Quick Check:

   Parentheses around condition = correct syntax [OK]

Hint: Remember: if (condition) { } in C [OK]

Common Mistakes:

• Omitting parentheses around condition
• Using square brackets instead of parentheses
• Adding 'then' keyword which C does not use

3. What will be the output of this C code?

int x = 10;
if (x > 5) {
    printf("Big\n");
} else {
    printf("Small\n");
}

medium

A. Compilation error

B. Small

C. No output

D. Big

Solution

1. Step 1: Evaluate the condition

   The variable x is 10, which is greater than 5, so the condition (x > 5) is true.

2. Step 2: Determine which branch runs

   Since the condition is true, the code inside the if block runs, printing "Big".

3. Final Answer:

   Big -> Option D

4. Quick Check:

   10 > 5 is true, so prints Big [OK]

Hint: Check condition true or false to pick output [OK]

Common Mistakes:

• Confusing which block runs on true
• Ignoring the newline character
• Thinking else block runs when condition is true

4. Find the error in this C code snippet:

int num = 7;
if num > 5 {
    printf("Yes\n");
} else {
    printf("No\n");
}

medium

A. Missing parentheses around the condition

B. Missing semicolon after if statement

C. Incorrect use of else keyword

D. Variable num not declared

Solution

1. Step 1: Check the if statement syntax

   The condition in an if statement must be inside parentheses in C.

2. Step 2: Identify the error

   The code uses if num > 5 { ... } without parentheses, which is invalid syntax.

3. Final Answer:

   Missing parentheses around the condition -> Option A

4. Quick Check:

   If condition needs ( ) in C [OK]

Hint: Always put condition inside ( ) for if [OK]

Common Mistakes:

• Forgetting parentheses in if condition
• Adding semicolon after if line incorrectly
• Misplacing braces

5. You want to write a program that prints "Even" if a number is divisible by 2, and "Odd" otherwise. Which code snippet correctly uses conditional logic to do this?

hard

A. if (num % 2 != 0) {
printf("Even\n");
} else {
printf("Odd\n");
}

B. if (num / 2 == 0) {
printf("Even\n");
} else {
printf("Odd\n");
}

C. if (num % 2 == 0) {
printf("Even\n");
} else {
printf("Odd\n");
}

D. if (num % 2 = 0) {
printf("Even\n");
} else {
printf("Odd\n");
}

Solution

1. Step 1: Understand the condition for even numbers

   A number is even if dividing by 2 leaves remainder 0, checked by num % 2 == 0.

2. Step 2: Check each option's condition

   if (num % 2 == 0) { printf("Even\n"); } else { printf("Odd\n"); } correctly uses num % 2 == 0. if (num / 2 == 0) { printf("Even\n"); } else { printf("Odd\n"); } uses division instead of modulo. if (num % 2 = 0) { printf("Even\n"); } else { printf("Odd\n"); } uses assignment (=) instead of comparison (==). if (num % 2 != 0) { printf("Even\n"); } else { printf("Odd\n"); } reverses the logic.

3. Final Answer:

   if (num % 2 == 0) { printf("Even\n"); } else { printf("Odd\n"); } -> Option C

4. Quick Check:

   Modulo 2 equals 0 means even [OK]

Hint: Use modulo (%) to check divisibility [OK]

Common Mistakes:

• Using = instead of == in condition
• Using division instead of modulo
• Reversing if-else logic