Ternary operator in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to assign $result to 'Yes' if $a is true, otherwise 'No'.

PHP

$result = $a ? [1] : 'No';

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

A'No'

B'Yes'

Ctrue

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Putting 'No' as the first value, which is for the false case.

Using true or false instead of the string 'Yes'.

The ternary operator syntax is condition ? value_if_true : value_if_false. Here, if $a is true, $result should be 'Yes'.

2fill in blank

medium

Complete the code to assign $status to 'adult' if $age is 18 or more, otherwise 'minor'.

PHP

$status = ($age >= 18) ? [1] : 'minor';

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

A'minor'

B$age

C18

D'adult'

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping 'adult' and 'minor' values.

Using the number 18 instead of the string 'adult'.

If $age is 18 or more, $status should be 'adult'. The ternary operator returns 'adult' when the condition is true.

3fill in blank

hard

Fix the error in the ternary operator to assign $message to 'Success' if $code equals 200, else 'Error'.

PHP

$message = ($code == 200) ? [1] : 'Error';

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

A'Success'

B'Error'

C200

DSuccess

Attempts:

3 left

💡 Hint

Common Mistakes

Using Success without quotes causing undefined constant error.

Using 200 instead of the string 'Success'.

In PHP, strings must be in quotes. 'Success' is the correct string value to assign.

4fill in blank

hard

Fill both blanks to assign $output to 'even' if $num is divisible by 2, else 'odd'.

PHP

$output = ($num [1] 2 == 0) ? [2] : 'odd';

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

A%

B'even'

C'odd'

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using == instead of % for modulus.

Assigning 'odd' in the true case.

The modulus operator % checks divisibility. If remainder is 0, $num is even, so assign 'even'.

5fill in blank

hard

Fill all three blanks to create a ternary that assigns $result to uppercase $word if $flag is true, else lowercase $word.

PHP

$result = $flag ? [1]([2]) : [3]($word);

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

Astrtoupper

B$word

Cstrtolower

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same function for both true and false cases.

Not passing $word as argument.

If $flag is true, convert $word to uppercase using strtoupper($word), else lowercase with strtolower($word).

Practice

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

easy

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

B. It creates a loop that runs twice.

C. It defines a function with two parameters.

D. It comments out a line of code.

Solution

1. Step 1: Understand the ternary operator format

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

2. Step 2: Identify 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: Think: condition true? pick first : else pick second [OK]

Common Mistakes:

• Confusing ternary with loops
• Thinking it defines functions
• Assuming it comments code

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

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

   Only condition ? value_if_true : value_if_false; matches the correct syntax exactly.

3. Final Answer:

   condition ? value_if_true : value_if_false; -> Option C

4. Quick Check:

   Syntax = 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 PHP code?

$age = 20;
$result = ($age >= 18) ? 'Adult' : 'Minor';
echo $result;

medium

A. Adult

B. Error

C. 20

D. Minor

Solution

1. Step 1: Evaluate the condition

   $age is 20, so ($age >= 18) is true.

2. Step 2: Apply ternary operator

   Since condition is true, $result is set to 'Adult'.

3. Final Answer:

   Adult -> Option A

4. Quick Check:

   20 >= 18 ? 'Adult' : 'Minor' = 'Adult' [OK]

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

Common Mistakes:

• Assuming output is the number 20
• Confusing true and false branches
• Expecting syntax error

4. Find the error in this PHP code using ternary operator:

$score = 75;
$grade = $score > 60 ? 'Pass' 'Fail';
echo $grade;

medium

A. Wrong variable name used

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

C. Ternary operator cannot be used with strings

D. Missing semicolon after echo

Solution

1. Step 1: Check ternary operator syntax

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

2. Step 2: Identify the missing colon

   Code has 'Pass' 'Fail' without ':' causing syntax error.

3. Final Answer:

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

4. Quick Check:

   Syntax needs ? true : false [OK]

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

Common Mistakes:

• Omitting colon ':'
• Using comma instead of colon
• Confusing variable names

5. Given an array of numbers, which PHP code correctly uses the ternary operator to create a new array labeling each number as 'Even' or 'Odd'?

hard

A. $numbers = [1,2,3]; $labels = array_map(fn($n) => $n % 2 == 1 ? 'Even' : 'Odd', $numbers);

B. $numbers = [1,2,3]; $labels = array_map(fn($n) => $n % 2 == 0 ? 'Odd' : 'Even', $numbers);

C. $numbers = [1,2,3]; $labels = array_map(fn($n) => $n % 2 ? 'Even' : 'Odd', $numbers);

D. $numbers = [1,2,3]; $labels = array_map(fn($n) => $n % 2 == 0 ? 'Even' : 'Odd', $numbers);

Solution

1. Step 1: Understand the condition for even or odd

   A number is even if $n % 2 == 0, otherwise odd.

2. Step 2: Check each option's condition and labels

   $numbers = [1,2,3]; $labels = array_map(fn($n) => $n % 2 == 0 ? 'Even' : 'Odd', $numbers); correctly labels even numbers as 'Even' and odd as 'Odd'. Others swap or invert labels.

3. Final Answer:

   $numbers = [1,2,3]; $labels = array_map(fn($n) => $n % 2 == 0 ? 'Even' : 'Odd', $numbers); -> Option D

4. Quick Check:

   Even check with ternary = correct labeling [OK]

Hint: Even numbers have remainder 0 when divided by 2 [OK]

Common Mistakes:

• Swapping 'Even' and 'Odd' labels
• Using wrong modulo condition
• Confusing truthy/falsy values in ternary