Ternary operator in PHP

Introduction

The ternary operator helps you choose between two values quickly in one line. It makes your code shorter and easier to read.

When you want to set a variable based on a simple condition.

When you want to print one message if something is true, and another if it is false.

When you want to return a value from a function depending on a condition.

When you want to avoid writing a full if-else block for a quick choice.

Syntax

PHP

$result = (condition) ? value_if_true : value_if_false;

The condition is checked first.

If the condition is true, the value after the question mark (?) is used.

If the condition is false, the value after the colon (:) is used.

Examples

This sets $status to 'Adult' if $age is 18 or more, otherwise 'Minor'.

PHP

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

This prints 'Pass' if the score is 60 or more, else 'Fail'.

PHP

$score = 75;
$message = ($score >= 60) ? 'Pass' : 'Fail';
echo $message;

This prints a welcome message if logged in, otherwise asks to log in.

PHP

$is_logged_in = false;
echo $is_logged_in ? 'Welcome back!' : 'Please log in.';

Sample Program

This program checks if the temperature is above 25. If yes, it says 'Hot', otherwise 'Cold'.

PHP

<?php
$temperature = 30;
$weather = ($temperature > 25) ? 'Hot' : 'Cold';
echo "The weather is $weather.";
?>

Important Notes

You can nest ternary operators but it can make code hard to read.

Use parentheses to make complex conditions clear.

Summary

The ternary operator is a short way to choose between two values.

It uses the format: condition ? value_if_true : value_if_false.

It helps keep code simple and clean for quick decisions.

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