Ternary conditional operator in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to assign the smaller number to min using the ternary operator.

C Sharp (C#)

int a = 5;
int b = 10;
int min = (a < b) ? [1] : b;

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

A5

Ba

Cb

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Using b instead of a for the true part.

Putting the condition inside the blank.

The ternary operator checks if a < b. If true, it assigns a to min, otherwise b.

2fill in blank

medium

Complete the code to assign result as "Even" or "Odd" based on num.

C Sharp (C#)

int num = 7;
string result = (num % 2 == 0) ? [1] : "Odd";

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

A"Even"

B"Odd"

Cnum

D"Number"

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning "Odd" for the true part.

Using num instead of a string.

The ternary operator checks if num is even. If true, it assigns "Even", else "Odd".

3fill in blank

hard

Fix the error in the ternary operator to assign status correctly.

C Sharp (C#)

int score = 85;
string status = score >= 60 ? "Pass" [1] "Fail";

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

A?

B;

C,

D:

Attempts:

3 left

💡 Hint

Common Mistakes

Using a semicolon or comma instead of a colon.

Omitting the colon entirely.

The ternary operator requires a colon : between the true and false expressions.

4fill in blank

hard

Fill both blanks to assign message based on age.

C Sharp (C#)

int age = 20;
string message = (age >= [1]) ? "Adult" : [2];

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

A18

B"Minor"

C"Child"

D21

Attempts:

3 left

💡 Hint

Common Mistakes

Using 21 instead of 18 for the age check.

Using "Child" instead of "Minor" for the false part.

If age is 18 or more, message is "Adult"; otherwise, it is "Minor".

5fill in blank

hard

Fill all three blanks to create a dictionary that maps numbers to "Even" or "Odd" strings.

C Sharp (C#)

var parity = new Dictionary<int, string>()
{
    {1, [1],
    {2, [2],
    {3, [3]
};

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

A"Odd"

B"Even"

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning "Even" to odd numbers.

Mixing up the order of values.

Numbers 1 and 3 are odd, so map to "Odd"; number 2 is even, so map to "Even".

Practice

1. What does the ternary conditional operator condition ? value_if_true : value_if_false do in C#?

easy

A. It executes both value_if_true and value_if_false regardless of the condition.

B. It is used to declare variables in C#.

C. It only checks the condition but does not return any value.

D. It returns value_if_true if the condition is true, otherwise value_if_false.

Solution

1. Step 1: Understand the ternary operator syntax

   The ternary operator uses a condition followed by a question mark, then two values separated by a colon.

2. Step 2: Determine what it returns based on the condition

   If the condition is true, it returns the first value; if false, it returns the second value.

3. Final Answer:

   It returns value_if_true if the condition is true, otherwise value_if_false. -> Option D

4. Quick Check:

   condition ? true_value : false_value = returns true_value if condition true [OK]

Hint: Remember: condition ? trueValue : falseValue returns one value [OK]

Common Mistakes:

• Thinking both values run regardless of condition
• Confusing ternary operator with if statement
• Believing it does not return a value

2. Which of the following is the correct syntax for using the ternary operator in C#?

easy

A. int result = (x > 0) : 1 ? 0;

B. int result = (x > 0) ? 1 : 0;

C. int result = (x > 0) ? {1, 0};

D. int result = (x > 0) ? 1;

Solution

1. Step 1: Review the ternary operator syntax

   The correct syntax is: condition ? value_if_true : value_if_false;

2. Step 2: Check each option for syntax correctness

   int result = (x > 0) ? 1 : 0; matches the correct syntax. Options A, B, and D have syntax errors or missing parts.

3. Final Answer:

   int result = (x > 0) ? 1 : 0; -> Option B

4. Quick Check:

   Correct ternary syntax uses ? and : in order [OK]

Hint: Syntax is: condition ? trueValue : falseValue; [OK]

Common Mistakes:

• Using curly braces instead of colon
• Swapping ? and : positions
• Omitting the false value after colon

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

int a = 5;
string result = (a % 2 == 0) ? "Even" : "Odd";
Console.WriteLine(result);

medium

A. Odd

B. Even

C. 5

D. Error

Solution

1. Step 1: Evaluate the condition (a % 2 == 0)

   Since a = 5, 5 % 2 equals 1, which is not 0, so the condition is false.

2. Step 2: Determine which value the ternary operator returns

   Because the condition is false, it returns "Odd".

3. Final Answer:

   Odd -> Option A

4. Quick Check:

   5 % 2 == 0 is false, so output is "Odd" [OK]

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

Common Mistakes:

• Assuming 5 is even
• Confusing modulus operator result
• Expecting numeric output instead of string

4. Identify the error in this C# code using the ternary operator:

int x = 10;
string output = x > 5 ? "High" "Low";
Console.WriteLine(output);

medium

A. Condition must be inside parentheses

B. Missing semicolon at the end of the line

C. Missing colon ':' between true and false values

D. Incorrect variable type for output

Solution

1. Step 1: Check ternary operator syntax in the code

   The ternary operator requires a colon ':' between the true and false values.

2. Step 2: Identify the missing colon

   The code has "High" "Low" without a colon, which causes a syntax error.

3. Final Answer:

   Missing colon ':' between true and false values -> Option C

4. Quick Check:

   condition ? trueValue : falseValue needs ':' separator [OK]

Hint: Always include ':' between true and false parts [OK]

Common Mistakes:

• Forgetting the colon ':'
• Adding extra quotes or commas
• Misplacing parentheses

5. Given a list of integers, which C# code snippet correctly uses the ternary operator to create a new list of strings labeling each number as "Positive" or "Non-positive"?

hard

A. var labels = numbers.Select(n => n > 0 ? "Positive" : "Non-positive").ToList();

B. var labels = numbers.Select(n => n > 0 ? "Positive" "Non-positive").ToList();

C. var labels = numbers.Select(n => if (n > 0) "Positive" else "Non-positive").ToList();

D. var labels = numbers.Select(n => n > 0 ? "Positive" : ).ToList();

Solution

1. Step 1: Understand the use of ternary operator inside LINQ Select

   The ternary operator must have a condition, true value, and false value separated by '?' and ':'.

2. Step 2: Check each option for correct syntax and logic

   var labels = numbers.Select(n => n > 0 ? "Positive" : "Non-positive").ToList(); correctly uses the ternary operator inside Select. Options B, C, and D have syntax errors or invalid expressions.

3. Final Answer:

   var labels = numbers.Select(n => n > 0 ? "Positive" : "Non-positive").ToList(); -> Option A

4. Quick Check:

   Correct ternary inside Select uses ? and : with both values [OK]

Hint: Use ? and : correctly inside lambda expressions [OK]

Common Mistakes:

• Omitting colon ':' in ternary operator
• Using if-else inside lambda without braces
• Leaving false value empty