Comparison operators in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if variable a is greater than b.

C Sharp (C#)

bool result = a [1] b;

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

A>

B<

C<=

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using == instead of > to compare values.

Using < which means less than.

The > operator checks if the left value is greater than the right value.

2fill in blank

medium

Complete the code to check if score is less than or equal to 100.

C Sharp (C#)

if (score [1] 100) {
    Console.WriteLine("Valid score");
}

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

A<=

B<

C>=

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using < which excludes equality.

Using >= which means greater than or equal.

The operator <= means 'less than or equal to'.

3fill in blank

hard

Fix the error in the comparison to check if age is not equal to 18.

C Sharp (C#)

if (age [1] 18) {
    Console.WriteLine("Age is not 18");
}

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

A==

B!=

C<>

D=

Attempts:

3 left

💡 Hint

Common Mistakes

Using = which is assignment, not comparison.

Using <> which is not valid in C#.

The operator != means 'not equal to' in C#.

4fill in blank

hard

Fill both blanks to create a dictionary that maps numbers to their squares only if the number is greater than 3.

C Sharp (C#)

var squares = new Dictionary<int, int> {
    { [1], [2] }
};

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

A4

B16

C3

D9

Attempts:

3 left

💡 Hint

Common Mistakes

Using 3 as key which is not greater than 3.

Using a value that is not the square of the key.

The key is 4 (greater than 3) and the value is its square 16.

5fill in blank

hard

Fill all three blanks to create a LINQ query that selects numbers from 1 to 5 where the number is less than 4 and doubles them.

C Sharp (C#)

var result = from num in Enumerable.Range(1, 5)
             where num [1] 4
             select num [2] [3];

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

A<

B*

C2

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using greater than operator in the where clause.

Using addition instead of multiplication for doubling.

The query filters numbers less than 4 and selects their doubles by multiplying by 2.

Practice

1. Which of the following comparison operators checks if two values are equal in C#?

easy

A. >

B. =

C. !=

D. ==

Solution

1. Step 1: Understand the equality operator

   The operator == is used to check if two values are equal in C#.

2. Step 2: Differentiate from assignment and other operators

   = is for assignment, != checks inequality, and > checks if left is greater than right.

3. Final Answer:

   == -> Option D

4. Quick Check:

   Equality operator = == [OK]

Hint: Use double equals (==) to check equality, not single equals [OK]

Common Mistakes:

• Using single equals (=) instead of double equals (==)
• Confusing != with == operator
• Using > when checking equality

2. Which of the following is the correct syntax to check if variable x is not equal to 10 in C#?

easy

A. if (x != 10)

B. if (x =! 10)

C. if (x = 10)

D. if (x ==! 10)

Solution

1. Step 1: Identify the correct not equal operator

   The operator != is used to check if two values are not equal in C#.

2. Step 2: Check syntax correctness

   if (x != 10) is correct syntax. The others have incorrect operator placement or use assignment instead of comparison.

3. Final Answer:

   if (x != 10) -> Option A

4. Quick Check:

   Not equal operator = != [OK]

Hint: Use != to check not equal, watch operator order carefully [OK]

Common Mistakes:

• Writing =! instead of != operator
• Using single = instead of comparison operator
• Combining == and ! incorrectly

3. What is the output of the following C# code?

int a = 5;
int b = 8;
Console.WriteLine(a > b);

medium

A. 5

B. True

C. False

D. 8

Solution

1. Step 1: Compare values of a and b

   Variable a is 5 and b is 8. The expression a > b checks if 5 is greater than 8.

2. Step 2: Evaluate the comparison

   Since 5 is not greater than 8, the expression returns false.

3. Final Answer:

   False -> Option C

4. Quick Check:

   5 > 8 = False [OK]

Hint: Compare values carefully; 5 is not greater than 8 [OK]

Common Mistakes:

• Assuming 5 > 8 is true
• Confusing output with variable values
• Expecting numeric output instead of boolean

4. Find the error in this C# code snippet:

int x = 10;
if (x = 5)
{
    Console.WriteLine("Equal");
}

medium

A. Using assignment (=) instead of comparison (==) in if condition

B. Missing semicolon after if statement

C. Incorrect variable declaration

D. Console.WriteLine syntax error

Solution

1. Step 1: Check the if condition syntax

   The condition uses = which assigns 5 to x instead of comparing.

2. Step 2: Correct operator usage

   Use == to compare values in conditions, so it should be if (x == 5).

3. Final Answer:

   Using assignment (=) instead of comparison (==) in if condition -> Option A

4. Quick Check:

   Comparison needs ==, not = [OK]

Hint: Use double equals (==) in conditions, not single equals (=) [OK]

Common Mistakes:

• Using = instead of == in if conditions
• Forgetting to use parentheses in if
• Misunderstanding assignment vs comparison

5. You want to check if a number n is between 10 and 20 inclusive in C#. Which condition correctly uses comparison operators?

hard

A. if (n > 10 || n < 20)

B. if (n >= 10 && n <= 20)

C. if (10 <= n <= 20)

D. if (n == 10 && n == 20)

Solution

1. Step 1: Understand range checking in C#

   C# does not support chained comparisons like 10 <= n <= 20. You must combine two comparisons with logical AND.

2. Step 2: Analyze each option

   if (n >= 10 && n <= 20) uses n >= 10 && n <= 20, which correctly checks if n is between 10 and 20 inclusive. if (10 <= n <= 20) is invalid syntax. if (n > 10 || n < 20) uses OR which is incorrect for range. if (n == 10 && n == 20) checks if n equals both 10 and 20 simultaneously, which is impossible.

3. Final Answer:

   if (n >= 10 && n <= 20) -> Option B

4. Quick Check:

   Use && to combine comparisons for ranges [OK]

Hint: Use && to combine two comparisons for range checks [OK]

Common Mistakes:

• Trying chained comparisons like 10 <= n <= 20
• Using || instead of && for range
• Checking impossible conditions with == for both ends