Ternary operator in C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to assign the smaller of two numbers to the variable min using the ternary operator.

C

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

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

A<

B>

C==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' instead of '<' will assign the larger number.

Using '==' or '!=' will not correctly compare sizes.

The ternary operator checks if 'a < b'. If true, 'min' gets 'a'; otherwise, it gets 'b'.

2fill in blank

medium

Complete the code to assign the string "even" or "odd" to result based on whether num is even or odd using the ternary operator.

C

int num = 7;
char *result = (num % 2 [1] 0) ? "odd" : "even";

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

A>

B!=

C==

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '==' will assign 'even' to odd numbers and vice versa.

Using '>' or '<' does not correctly check for evenness.

The condition checks if 'num % 2 != 0' to determine if the number is odd.

3fill in blank

hard

Fix the error in the ternary operator condition to correctly assign the absolute value of num to abs_val.

C

int num = -8;
int abs_val = (num [1] 0) ? -num : num;

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

A<

B!=

C==

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' will incorrectly negate positive numbers.

Using '==' or '!=' does not check negativity.

The condition should check if 'num < 0' to negate it and get the absolute value.

4fill in blank

hard

Fill both blanks to create a ternary operator that assigns "positive" if n is greater than zero, otherwise "non-positive".

C

int n = 3;
char *sign = (n [1] 0) ? "positive" : [2];

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

A>

B"non-positive"

C"negative"

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' in the first blank reverses the logic.

Assigning 'negative' instead of 'non-positive' changes the meaning.

The condition checks if 'n > 0'. If true, assign 'positive'; else assign 'non-positive'.

5fill in blank

hard

Fill all three blanks to create a ternary operator that assigns the maximum of x and y to max_val.

C

int x = 4, y = 9;
int max_val = (x [1] y) ? [2] : [3];

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

A>

Bx

Cy

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' reverses the logic and assigns the minimum.

Swapping 'x' and 'y' in the assignments changes the result.

The condition checks if 'x > y'. If true, 'max_val' is 'x'; otherwise, it is 'y'.

Practice

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

easy

A. It chooses one of two values based on the condition's truth.

B. It creates a loop that runs twice.

C. It declares a new variable.

D. It comments out code.

Solution

1. Step 1: Understand the ternary operator structure

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

2. Step 2: Determine its purpose

   It returns the first value if the condition is true, otherwise the second value.

3. Final Answer:

   It chooses one of two values based on the condition's truth. -> Option A

4. Quick Check:

   condition ? true_value : false_value = chooses value [OK]

Hint: Remember: condition ? true : false picks one value [OK]

Common Mistakes:

• Thinking it creates loops
• Confusing it with variable declaration
• Assuming it comments code

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

easy

A. condition : value_if_true ? value_if_false;

B. condition ? value_if_true : value_if_false;

C. condition ? value_if_true, value_if_false;

D. condition ? (value_if_true : value_if_false);

Solution

1. Step 1: Recall ternary operator syntax

   The correct syntax is: condition ? value_if_true : value_if_false;

2. Step 2: Check each option

   condition ? value_if_true : value_if_false; matches the correct syntax exactly; others have misplaced symbols or punctuation.

3. Final Answer:

   condition ? value_if_true : value_if_false; -> Option B

4. Quick Check:

   Syntax is condition ? true : false; [OK]

Hint: Remember: question mark before colon in ternary [OK]

Common Mistakes:

• Swapping question mark and colon
• Using comma instead of colon
• Adding extra parentheses incorrectly

3. What is the output of this C code?

int x = 5;
int y = (x > 3) ? 10 : 20;
printf("%d", y);

medium

A. 10

B. 20

C. 5

D. Syntax error

Solution

1. Step 1: Evaluate the condition (x > 3)

   Since x is 5, 5 > 3 is true.

2. Step 2: Apply ternary operator

   Because condition is true, y is assigned 10.

3. Final Answer:

   10 -> Option A

4. Quick Check:

   (5 > 3) ? 10 : 20 = 10 [OK]

Hint: Check if condition is true, then pick first value [OK]

Common Mistakes:

• Choosing the false value by mistake
• Confusing variable values
• Thinking it causes syntax error

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

int a = 10;
int b = 20;
int max = a > b ? a, b;

medium

A. Missing colon ':' between values

B. Incorrect variable declaration

C. No error, code is correct

D. Using comma instead of colon in ternary

Solution

1. Step 1: Check ternary operator syntax

   The ternary operator requires a colon ':' between the two possible values.

2. Step 2: Identify the mistake

   The code uses a comma ',' instead of a colon ':', which is incorrect syntax.

3. Final Answer:

   Using comma instead of colon in ternary -> Option D

4. Quick Check:

   Ternary needs ':' not ',' [OK]

Hint: Ternary uses ':' not ',' between values [OK]

Common Mistakes:

• Using comma instead of colon
• Forgetting colon entirely
• Assuming code is correct

5. Given this code snippet, what will be the value of result?

int a = 0;
int b = 5;
int result = (a != 0) ? (b / a) : (b * 2);
printf("%d", result);

hard

A. 0

B. Division by zero error

C. 10

D. 5

Solution

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

   a is 0, so (0 != 0) is false.

2. Step 2: Apply ternary operator

   Since condition is false, result is assigned (b * 2) = 5 * 2 = 10.

3. Final Answer:

   10 -> Option C

4. Quick Check:

   Condition false, so result = b*2 = 10 [OK]

Hint: Check condition first to avoid division by zero [OK]

Common Mistakes:

• Assuming division happens causing error
• Ignoring false condition path
• Confusing variable values