If statement in C++ - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of nested if statements

What is the output of this C++ code snippet?

C++

int x = 5;
int y = 10;
if (x > 3) {
    if (y < 15) {
        std::cout << "A";
    } else {
        std::cout << "B";
    }
} else {
    std::cout << "C";
}

A A

B B

C C

D No output

💡 Hint

Check both conditions in the nested if statements carefully.

Since x is 5 (which is greater than 3) and y is 10 (which is less than 15), the first if and the nested if both run, printing 'A'.

❓ Predict Output

intermediate

If-else with logical operators

What will this C++ code print?

C++

int a = 7;
int b = 3;
if (a > 5 && b < 5) {
    std::cout << "X";
} else {
    std::cout << "Y";
}

A No output

B Y

C X

D Compilation error

💡 Hint

Both conditions in the if must be true for the if block to run.

a is 7 (greater than 5) and b is 3 (less than 5), so both conditions are true and 'X' is printed.

❓ Predict Output

advanced

If statement with assignment inside condition

What is the output of this C++ code?

C++

int x = 0;
if (x = 5) {
    std::cout << x;
} else {
    std::cout << 0;
}

A 5

B 0

C Compilation error

D Undefined behavior

💡 Hint

Remember that assignment inside if condition returns the assigned value.

The assignment 'x = 5' sets x to 5 and returns 5, which is true in the if condition, so it prints 5.

❓ Predict Output

advanced

If statement with multiple else if branches

What will this C++ code print?

C++

int n = 15;
if (n < 10) {
    std::cout << "Low";
} else if (n < 20) {
    std::cout << "Medium";
} else {
    std::cout << "High";
}

A No output

B Low

C High

D Medium

💡 Hint

Check which condition matches the value of n first.

n is 15, which is not less than 10 but less than 20, so it prints 'Medium'.

❓ Predict Output

expert

If statement with complex boolean expression

What is the output of this C++ code?

C++

bool a = true;
bool b = false;
bool c = true;
if ((a && b) || (b || c)) {
    std::cout << "Yes";
} else {
    std::cout << "No";
}

A No

B Yes

C Compilation error

D No output

💡 Hint

Evaluate the boolean expression step by step.

The expression (a && b) is false, but (b || c) is true, so the whole condition is true and prints 'Yes'.

Practice

1. What does an if statement do in C++?

easy

A. Defines a new variable

B. Repeats code multiple times

C. Runs code only if a condition is true

D. Ends the program immediately

Solution

1. Step 1: Understand the purpose of if statement

   An if statement checks a condition and runs code only when that condition is true.

2. Step 2: Compare with other options

   Repeating code is done by loops, defining variables is done by declarations, and ending the program is done by return or exit.

3. Final Answer:

   Runs code only if a condition is true -> Option C

4. Quick Check:

   If statement = runs code if true [OK]

Hint: If checks true condition to run code [OK]

Common Mistakes:

• Confusing if with loops
• Thinking if defines variables
• Believing if ends program

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

easy

A. if condition { cout << "Yes"; }

B. if condition: cout << "Yes";

C. if (condition) cout << "Yes"

D. if (condition) { cout << "Yes"; }

Solution

1. Step 1: Recall correct if syntax

   In C++, the condition must be inside parentheses and the code block inside curly braces.

2. Step 2: Check each option

   if (condition) { cout << "Yes"; } uses parentheses and curly braces correctly. if condition { cout << "Yes"; } misses parentheses. if condition: cout << "Yes"; uses colon which is invalid in C++. if (condition) cout << "Yes" misses curly braces which is allowed only for single statements but here it is incomplete.

3. Final Answer:

   if (condition) { cout << "Yes"; } -> Option D

4. Quick Check:

   Parentheses + braces = correct if syntax [OK]

Hint: Use parentheses for condition and braces for code [OK]

Common Mistakes:

• Missing parentheses
• Using colon instead of braces
• Omitting braces for multiple statements

3. What will be the output of this code?

int x = 10;
if (x > 5) {
  cout << "Hello";
} else {
  cout << "Bye";
}

medium

A. Hello

B. Bye

C. HelloBye

D. No output

Solution

1. Step 1: Evaluate the condition x > 5

   Since x is 10, which is greater than 5, the condition is true.

2. Step 2: Determine which block runs

   Because the condition is true, the code inside the if block runs, printing "Hello".

3. Final Answer:

   Hello -> Option A

4. Quick Check:

   10 > 5 is true, prints Hello [OK]

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

Common Mistakes:

• Confusing else output
• Ignoring condition result
• Assuming both blocks run

4. Find the error in this code snippet:

int a = 3;
if a > 0 {
  cout << "Positive";
}

medium

A. Missing semicolon after if

B. Condition must be inside parentheses

C. Missing curly braces

D. Variable a is not declared

Solution

1. Step 1: Check the if statement syntax

   The condition in an if statement must be inside parentheses.

2. Step 2: Identify the error

   The code writes if a > 0 { without parentheses, which is invalid syntax.

3. Final Answer:

   Condition must be inside parentheses -> Option B

4. Quick Check:

   If condition needs parentheses [OK]

Hint: Always put condition inside parentheses [OK]

Common Mistakes:

• Omitting parentheses
• Thinking semicolon needed after if
• Assuming braces optional always

5. You want to print "Even" if a number is even, and "Odd" if it is odd. Which code correctly uses an if statement to do this?

int num = 7;
// Your code here

hard

A. if (num % 2 == 0) { cout << "Even"; } else { cout << "Odd"; }

B. if (num / 2 == 0) { cout << "Even"; } else { cout << "Odd"; }

C. if (num % 2 = 0) { cout << "Even"; } else { cout << "Odd"; }

D. if (num % 2 != 0) { cout << "Even"; } else { cout << "Odd"; }

Solution

1. Step 1: Understand how to check even numbers

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

2. Step 2: Analyze each option

   if (num % 2 == 0) { cout << "Even"; } else { cout << "Odd"; } correctly uses num % 2 == 0. if (num / 2 == 0) { cout << "Even"; } else { cout << "Odd"; } uses division instead of modulo, which is wrong. if (num % 2 = 0) { cout << "Even"; } else { cout << "Odd"; } uses assignment = instead of comparison ==. if (num % 2 != 0) { cout << "Even"; } else { cout << "Odd"; } reverses the logic.

3. Final Answer:

   if (num % 2 == 0) { cout << "Even"; } else { cout << "Odd"; } -> Option A

4. Quick Check:

   Modulo 2 equals 0 means even [OK]

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

Common Mistakes:

• Using division instead of modulo
• Using = instead of ==
• Reversing condition logic