Ternary operator in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this PHP code using ternary operator?

Consider the following PHP code snippet. What will it output?

PHP

<?php
$score = 75;
$result = $score >= 60 ? 'Pass' : 'Fail';
echo $result;
?>

A Error

B Fail

C 75

D Pass

💡 Hint

Check the condition before the question mark and what happens if true or false.

The condition $score >= 60 is true because 75 is greater than 60, so the expression returns 'Pass'.

❓ Predict Output

intermediate

What does this nested ternary operator output?

Analyze the output of this PHP code with nested ternary operators.

PHP

<?php
$age = 20;
$status = $age < 13 ? 'Child' : ($age < 20 ? 'Teen' : 'Adult');
echo $status;
?>

A Adult

B Teen

C Child

D Error

💡 Hint

Check each condition from left to right carefully.

Since 20 is not less than 13 and not less than 20, the last option 'Adult' is chosen.

🔧 Debug

advanced

What error does this PHP ternary code produce?

Identify the error caused by this PHP code snippet.

PHP

<?php
$value = 10;
$result = $value > 5 ? 'High' 'Low';
echo $result;
?>

A Parse error: syntax error

B Outputs 'HighLow'

C Outputs 'High'

D Undefined variable error

💡 Hint

Check the syntax around the ternary operator carefully.

The ternary operator requires a colon ':' between the true and false expressions. Missing colon causes syntax error.

❓ Predict Output

advanced

What is the output of this PHP code with ternary and assignment?

What will this PHP code print?

PHP

<?php
$a = 0;
$b = $a ?: 5;
echo $b;
?>

A 0

B Error

C 5

D null

💡 Hint

The ?: operator returns the left value if it is truthy, otherwise the right value.

Since 0 is considered false in PHP, $b gets assigned 5.

🧠 Conceptual

expert

How many items are in the resulting array after this PHP code?

What is the count of elements in the array produced by this code?

PHP

<?php
$array = [
  'a' => 1,
  'b' => 2,
  'c' => 3
];
$result = [];
foreach ($array as $key => $value) {
  $result[$key] = $value > 1 ? $value * 2 : $value;
}
echo count($result);
?>

A 2

B 3

C 1

D 0

💡 Hint

The foreach loop adds one element per original array item.

The loop runs 3 times, adding 3 elements to $result regardless of ternary outcome.

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