Ternary operator in PHP - Mini Project: Build & Apply

Using the Ternary Operator in PHP

📖 Scenario: You are creating a simple PHP script to check if a person is old enough to vote. Voting age is 18 years or older.

🎯 Goal: Build a PHP script that uses the ternary operator to decide if a person can vote based on their age.

📋 What You'll Learn

Create a variable called age with a specific integer value.

Create a variable called voting_age set to 18.

Use the ternary operator to create a variable can_vote that stores the string 'Yes' if age is greater than or equal to voting_age, otherwise 'No'.

Print the value of can_vote.

💡 Why This Matters

🌍 Real World

Ternary operators are used in real-world PHP scripts to make quick decisions without writing long if-else statements.

💼 Career

Understanding ternary operators helps you write cleaner and shorter code, a valuable skill for PHP developers.

1

Create the age variable

Create a variable called age and set it to the integer 20.

PHP

<?php

// Create a variable called age and set it to 20
// Your code here

Hint

Use $age = 20; to create the variable.

2

Create the voting_age variable

Create a variable called voting_age and set it to the integer 18.

PHP

<?php

$age = 20;

// Create a variable called voting_age and set it to 18
// Your code here

Hint

Use $voting_age = 18; to create the variable.

3

Use the ternary operator to set can_vote

Use the ternary operator to create a variable called can_vote that stores the string 'Yes' if age is greater than or equal to voting_age, otherwise 'No'.

PHP

<?php

$age = 20;
$voting_age = 18;

// Use the ternary operator to set can_vote to 'Yes' or 'No'
// Your code here

Hint

Use $can_vote = ($age >= $voting_age) ? 'Yes' : 'No'; to assign the value.

4

Print the result

Print the value of the variable can_vote using echo.

PHP

= $voting_age) ? 'Yes' : 'No';

// Print the value of can_vote
// Your code here

Hint

Use echo $can_vote; to print the result.

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