If statement execution flow in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if the number is positive.

C Sharp (C#)

if (number [1] 0) {
    Console.WriteLine("Positive number");
}

Drag options to blanks, or click blank then click option'

A==

B>

C<

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' will check for negative numbers.

Using '==' checks only if number equals zero, not positive.

The condition should check if the number is greater than zero to be positive.

2fill in blank

medium

Complete the code to print "Even" when the number is divisible by 2.

C Sharp (C#)

if (number [1] 2 == 0) {
    Console.WriteLine("Even");
}

Drag options to blanks, or click blank then click option'

A%

B+

C-

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' or '-' instead of '%' will not check divisibility.

Using '*' will multiply, not check remainder.

The modulus operator '%' gives the remainder. If remainder is 0 when divided by 2, the number is even.

3fill in blank

hard

Fix the error in the if statement to correctly check if age is at least 18.

C Sharp (C#)

if (age [1] 18) {
    Console.WriteLine("Adult");
}

Drag options to blanks, or click blank then click option'

A<=

B==

C<

D>=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<=' checks if age is less than or equal to 18, which is incorrect here.

Using '==' checks only if age equals 18, not greater.

To check if age is at least 18, use '>=' which means greater than or equal to 18.

4fill in blank

hard

Fill both blanks to print "Teenager" if age is between 13 and 19 inclusive.

C Sharp (C#)

if (age [1] 13 && age [2] 19) {
    Console.WriteLine("Teenager");
}

Drag options to blanks, or click blank then click option'

A>=

B<

C<=

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '<=' excludes 19 from the range.

Using '>' instead of '>=' excludes 13 from the range.

The age should be greater than or equal to 13 and less than or equal to 19 to be a teenager.

5fill in blank

hard

Fill the blanks to print "Grade A" if score is above 90, "Grade B" if score is above 80, else "Grade C".

C Sharp (C#)

if (score [1] 90) {
    Console.WriteLine("Grade A");
} else if (score [2] 80) {
    Console.WriteLine("Grade B");
} else {
    Console.WriteLine("Grade C");
}

Drag options to blanks, or click blank then click option'

A>=

B>

C<=

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>=' includes 90 in Grade A, but the question says 'above 90'.

Using '<=' in the else if condition is incorrect here.

Use '>' to check if score is strictly greater than 90 or 80. The else covers scores less than or equal to 80.

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