If statement execution flow in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of nested if-else statements

What is the output of the following C# code?

C Sharp (C#)

int x = 10;
int y = 20;
if (x > 5)
{
    if (y < 15)
        Console.WriteLine("A");
    else
        Console.WriteLine("B");
}
else
{
    Console.WriteLine("C");
}

A A

B No output

C C

D B

💡 Hint

Check the conditions inside both if statements carefully.

The outer if checks if x > 5, which is true (10 > 5). Then the inner if checks if y < 15, which is false (20 < 15 is false). So the else branch of the inner if runs, printing "B".

❓ Predict Output

intermediate

If-else if-else chain output

What will be printed when this code runs?

C Sharp (C#)

int score = 75;
if (score >= 90)
    Console.WriteLine("Excellent");
else if (score >= 70)
    Console.WriteLine("Good");
else
    Console.WriteLine("Try again");

A Try again

B Good

C Excellent

D No output

💡 Hint

Check which condition matches the score value first.

The score is 75, which is not >= 90, so the first if is false. The else if checks if score >= 70, which is true, so it prints "Good" and skips the else.

❓ Predict Output

advanced

If statement with multiple conditions

What is the output of this code snippet?

C Sharp (C#)

int a = 5;
int b = 10;
if (a > 0 && b < 5)
    Console.WriteLine("X");
else if (a > 0 || b < 5)
    Console.WriteLine("Y");
else
    Console.WriteLine("Z");

A Y

B No output

C Z

D X

💡 Hint

Evaluate each condition carefully using logical AND and OR.

The first if condition (a > 0 && b < 5) is false because b < 5 is false (10 < 5 is false). The else if condition (a > 0 || b < 5) is true because a > 0 is true. So it prints "Y".

❓ Predict Output

advanced

If statement with assignment inside condition

What will be printed by this code?

C Sharp (C#)

int x = 0;
if ((x = 5) > 3)
    Console.WriteLine(x);
else
    Console.WriteLine("No");

A 5

B 0

C No

D Compilation error

💡 Hint

Remember that assignment inside if condition changes the variable value.

The assignment (x = 5) sets x to 5, then checks if 5 > 3, which is true. So it prints the value of x, which is 5.

🧠 Conceptual

expert

If statement execution flow with multiple conditions and side effects

Consider the following code. What is the final value of variable result after execution?

C Sharp (C#)

int a = 2;
int b = 3;
int result = 0;
if (a++ > 2 && ++b > 3)
    result = a + b;
else
    result = a - b;

A result = 6

B result = 3

C result = 0

D result = 5

💡 Hint

Remember how post-increment and pre-increment operators work and short-circuit evaluation.

The condition a++ > 2 evaluates as 2 > 2 (false), but a is incremented to 3 after. Because the first condition is false, the second condition (++b > 3) is not evaluated due to short-circuit AND. b remains 3. So the else branch runs: result = a - b = 3 - 3 = 0.

Practice

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

easy

A. It defines a new variable.

B. It repeats code multiple times.

C. It chooses which code to run based on a condition.

D. It stops the program immediately.

Solution

1. Step 1: Understand the purpose of if

   An if statement checks a condition to decide which code runs next.

2. Step 2: Compare options

   Only It chooses which code to run based on a condition. describes choosing code based on a condition, which matches the if statement's role.

3. Final Answer:

   It chooses which code to run based on a condition. -> Option C

4. Quick Check:

   if chooses code path = C [OK]

Hint: If checks true/false to pick code path quickly [OK]

Common Mistakes:

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

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

easy

A. if (x > 5) Console.WriteLine("Yes") end

B. if x > 5 then Console.WriteLine("Yes")

C. if x > 5: Console.WriteLine("Yes")

D. if (x > 5) { Console.WriteLine("Yes"); }

Solution

1. Step 1: Review C# if syntax

   C# requires parentheses around the condition and braces for the block.

2. Step 2: Check each option

   if (x > 5) { Console.WriteLine("Yes"); } uses parentheses and braces correctly; others use wrong keywords or punctuation.

3. Final Answer:

   if (x > 5) { Console.WriteLine("Yes"); } -> Option D

4. Quick Check:

   Correct C# if syntax = D [OK]

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

Common Mistakes:

• Omitting parentheses around condition
• Using Python or other language syntax
• Missing braces for code block

3. What will this code print?

int x = 10;
if (x < 5) {
  Console.WriteLine("Less");
} else {
  Console.WriteLine("More or equal");
}

medium

A. Less

B. More or equal

C. Nothing

D. Error

Solution

1. Step 1: Evaluate the condition

   The condition x < 5 is false because x is 10.

2. Step 2: Determine which block runs

   Since the condition is false, the else block runs, printing "More or equal".

3. Final Answer:

   More or equal -> Option B

4. Quick Check:

   Condition false -> else runs = A [OK]

Hint: If false, else block runs [OK]

Common Mistakes:

• Thinking if block runs when false
• Ignoring else block
• Confusing < with >

4. Find the error in this code:

int num = 7;
if num > 5 {
  Console.WriteLine("Big");
} else {
  Console.WriteLine("Small");
}

medium

A. Missing parentheses around the condition

B. Missing semicolon after if

C. Wrong keyword else

D. Variable num not declared

Solution

1. Step 1: Check if statement syntax

   C# requires parentheses around the condition in an if statement.

2. Step 2: Identify the error

   The code has if num > 5 { without parentheses, causing a syntax error.

3. Final Answer:

   Missing parentheses around the condition -> Option A

4. Quick Check:

   Parentheses needed in if condition = A [OK]

Hint: Always put condition inside parentheses in if [OK]

Common Mistakes:

• Forgetting parentheses in if
• Adding semicolon after if line
• Misusing else keyword

5. You want to print "Positive", "Negative", or "Zero" based on an integer n. Which code correctly uses if statements to do this?

hard

A. if (n > 0) { Console.WriteLine("Positive"); } else if (n < 0) { Console.WriteLine("Negative"); } else { Console.WriteLine("Zero"); }

B. if (n > 0) Console.WriteLine("Positive"); if (n < 0) Console.WriteLine("Negative"); else Console.WriteLine("Zero");

C. if (n > 0) { Console.WriteLine("Positive"); } else { if (n > 0) { Console.WriteLine("Negative"); } else { Console.WriteLine("Zero"); } }

D. if (n > 0) { Console.WriteLine("Positive"); } else if (n <= 0) { Console.WriteLine("Zero"); } else { Console.WriteLine("Negative"); }

Solution

1. Step 1: Understand the logic needed

   We need to check if n is greater than 0, less than 0, or exactly 0.

2. Step 2: Analyze each option

   if (n > 0) { Console.WriteLine("Positive"); } else if (n < 0) { Console.WriteLine("Negative"); } else { Console.WriteLine("Zero"); } correctly uses if, else if, and else to cover all cases without overlap or missing conditions.

3. Final Answer:

   if (n > 0) { Console.WriteLine("Positive"); } else if (n < 0) { Console.WriteLine("Negative"); } else { Console.WriteLine("Zero"); } -> Option A

4. Quick Check:

   Proper if-else chain covers all cases = B [OK]

Hint: Use if-else if-else chain for multiple conditions [OK]

Common Mistakes:

• Using separate ifs causing multiple prints
• Wrong order of conditions
• Incorrect else condition logic