Nested conditional execution in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if a number is positive.

C Sharp (C#)

int number = 10;
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 number > 0 checks if the number is positive.

2fill in blank

medium

Complete the code to check if a number is positive and even.

C Sharp (C#)

int number = 8;
if (number > 0 && number [1] 2 == 0)
{
    Console.WriteLine("Positive even number");
}

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

A+

B/

C*

D%

Attempts:

3 left

💡 Hint

Common Mistakes

Using '/' checks division but not remainder.

Using '*' or '+' does not check evenness.

The modulus operator % checks the remainder. number % 2 == 0 means the number is even.

3fill in blank

hard

Fix the error in the nested if statement to check if a number is positive and less than 100.

C Sharp (C#)

int number = 50;
if (number > 0)
{
    if (number [1] 100)
    {
        Console.WriteLine("Number is positive and less than 100");
    }
}

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

A!=

B>

C<

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' checks if number is greater than 100, which is incorrect here.

Using '==' or '!=' checks equality, not range.

The inner condition should check if number < 100 to confirm it is less than 100.

4fill in blank

hard

Fill both blanks to create a nested if that checks if a number is positive and divisible by 5.

C Sharp (C#)

int number = 25;
if (number [1] 0)
{
    if (number [2] 5 == 0)
    {
        Console.WriteLine("Positive and divisible by 5");
    }
}

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

A>

B<

C%

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' for positivity.

Using '/' instead of '%' for divisibility check.

The first condition checks if the number is greater than zero. The second uses modulus '%' to check divisibility by 5.

5fill in blank

hard

Fill all three blanks to create a nested if that checks if a number is negative, odd, and less than -10.

C Sharp (C#)

int number = -15;
if (number [1] 0)
{
    if (number [2] 2 != 0)
    {
        if (number [3] -10)
        {
            Console.WriteLine("Negative, odd, and less than -10");
        }
    }
}

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

A<

B%

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' instead of '<' for negativity check.

Using wrong operator for odd check.

Using '>' instead of '<' for the last condition.

The first condition checks if number is less than zero (negative). The second uses modulus '%' to check if odd (remainder not zero). The third checks if number is less than -10.

Practice

1. What does nested conditional execution mean in C#?

easy

A. Running code without any conditions

B. Checking one condition inside another condition

C. Using only one if statement without else

D. Writing multiple if statements separately

Solution

1. Step 1: Understand the meaning of nested conditions

   Nested conditional execution means putting one if or else if statement inside another to check multiple conditions step-by-step.

2. Step 2: Compare options with definition

   Only Checking one condition inside another condition describes checking one condition inside another, which matches nested conditional execution.

3. Final Answer:

   Checking one condition inside another condition -> Option B

4. Quick Check:

   Nested condition = condition inside condition [OK]

Hint: Think of conditions inside conditions like boxes inside boxes [OK]

Common Mistakes:

• Confusing nested with multiple separate if statements
• Thinking nested means no else parts
• Believing nested means no conditions at all

2. Which of the following is the correct syntax for nested if statements in C#?

easy

A. if (x > 0) { if (x < 10) { Console.WriteLine("Inside"); } }

B. if x > 0 then if x < 10 then Console.WriteLine("Inside")

C. if (x > 0 if (x < 10) Console.WriteLine("Inside") else Console.WriteLine("Outside");

D. if (x > 0) { Console.WriteLine("Inside"); } else if (x < 10) { Console.WriteLine("Inside"); }

Solution

1. Step 1: Review C# nested if syntax

   Nested if means an if statement inside another if's braces, both with parentheses and braces.

2. Step 2: Check each option

   if (x > 0) { if (x < 10) { Console.WriteLine("Inside"); } } correctly uses braces and parentheses for nested if. if x > 0 then if x < 10 then Console.WriteLine("Inside") uses wrong syntax (no parentheses). if (x > 0 if (x < 10) Console.WriteLine("Inside") else Console.WriteLine("Outside"); misses braces and has syntax error (missing closing parenthesis). if (x > 0) { Console.WriteLine("Inside"); } else if (x < 10) { Console.WriteLine("Inside"); } is separate if-else, not nested.

3. Final Answer:

   if (x > 0) { if (x < 10) { Console.WriteLine("Inside"); } } -> Option A

4. Quick Check:

   Nested if needs braces and parentheses [OK]

Hint: Look for braces inside braces with proper parentheses [OK]

Common Mistakes:

• Omitting parentheses around conditions
• Missing braces for nested blocks
• Confusing else placement in nested if

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

int x = 5;
if (x > 0) {
  if (x < 10) {
    Console.WriteLine("A");
  } else {
    Console.WriteLine("B");
  }
} else {
  Console.WriteLine("C");
}

medium

A. A

B. B

C. C

D. No output

Solution

1. Step 1: Check outer if condition

   x = 5, so x > 0 is true, enter first if block.

2. Step 2: Check inner if condition

   Inside first if, check if x < 10. Since 5 < 10 is true, print "A".

3. Final Answer:

   A -> Option A

4. Quick Check:

   x=5 >0 and <10 prints A [OK]

Hint: Follow conditions step-by-step inside each if [OK]

Common Mistakes:

• Ignoring inner if and printing else block
• Confusing else belonging to which if
• Assuming no output if conditions are true

4. Find the error in this nested conditional code:

int y = 8;
if (y > 5)
  if (y < 10)
    Console.WriteLine("Inside");
  else
    Console.WriteLine("Outside");

medium

A. Missing braces causing else to pair with wrong if

B. Syntax error: missing semicolon after if

C. Variable y is not declared

D. No error, code runs fine

Solution

1. Step 1: Analyze if-else pairing without braces

   Without braces, else pairs with nearest if (the inner one). This is correct C# syntax.

2. Step 2: Check for errors

   The code compiles and runs fine with no syntax error, undefined variables, or crashes. Braces are recommended for clarity but not required here.

3. Final Answer:

   No error, code runs fine -> Option D

4. Quick Check:

   Code runs correctly without braces [OK]

Hint: Use braces to clearly group if-else blocks [OK]

Common Mistakes:

• Thinking semicolon needed after if
• Assuming else pairs with outer if
• Ignoring braces importance

5. You want to write a nested conditional in C# that prints "Small Positive" if a number is greater than 0 and less than 10, "Large Positive" if greater or equal to 10, and "Non-positive" otherwise. Which code correctly implements this?

hard

A. if (num < 10) { if (num > 0) { Console.WriteLine("Non-positive"); } else { Console.WriteLine("Small Positive"); } } else { Console.WriteLine("Large Positive"); }

B. if (num > 0 && num < 10) { Console.WriteLine("Small Positive"); } else if (num >= 10) { Console.WriteLine("Large Positive"); } else { Console.WriteLine("Non-positive"); }

C. if (num > 0) { if (num < 10) { Console.WriteLine("Small Positive"); } else { Console.WriteLine("Large Positive"); } } else { Console.WriteLine("Non-positive"); }

D. if (num > 0) { Console.WriteLine("Small Positive"); } else if (num < 10) { Console.WriteLine("Large Positive"); } else { Console.WriteLine("Non-positive"); }

Solution

1. Step 1: Understand conditions to check

   We want to check if num > 0 and num < 10 for "Small Positive", else if num >= 10 for "Large Positive", else "Non-positive".

2. Step 2: Check nested if logic

   if (num > 0) { if (num < 10) { Console.WriteLine("Small Positive"); } else { Console.WriteLine("Large Positive"); } } else { Console.WriteLine("Non-positive"); } correctly nests the second condition inside the first if (num > 0), checking num < 10 inside it, else prints "Large Positive". Else prints "Non-positive".

3. Final Answer:

   if (num > 0) { if (num < 10) { Console.WriteLine("Small Positive"); } else { Console.WriteLine("Large Positive"); } } else { Console.WriteLine("Non-positive"); } -> Option C

4. Quick Check:

   Nested if matches conditions exactly [OK]

Hint: Nest second condition inside first to separate ranges clearly [OK]

Common Mistakes:

• Using && instead of nested if for this logic
• Swapping else blocks incorrectly
• Not covering all cases properly