Control Flow Details

Ternary Choice

The ternary operator chooses between two expressions.

ternary `condition ? a : b` returns `a` when the condition is true, otherwise `b`.

Ternary Choice

age
ternary_choice.php
Replay: real traced execution (multi-file project)
<?php
$age = 18;
$ticket = $age >= 18 ? "adult" : "child";
$price = $ticket === "adult" ? 12 : 6;

echo "age=" . $age . "\n";
echo "ticket=" . $ticket . "\n";
echo "price=" . $price . "\n";

<?php
$age = 12;
$ticket = $age >= 18 ? "adult" : "child";
$price = $ticket === "adult" ? 12 : 6;

echo "age=" . $age . "\n";
echo "ticket=" . $ticket . "\n";
echo "price=" . $price . "\n";

<?php
$age = 30;
$ticket = $age >= 18 ? "adult" : "child";
$price = $ticket === "adult" ? 12 : 6;

echo "age=" . $age . "\n";
echo "ticket=" . $ticket . "\n";
echo "price=" . $price . "\n";

  1. $age ← 18, $ticket ← adult, $price ← 12

    1<?php2$age→ 18 = 18; //@age=12, 303$ticket→ adult = $age18 >= 18 ? "adult" : "child";4$price→ 12 = $ticketadult === "adult" ? 12 : 6;56echo "age=" . $age18 . "\n";7echo "ticket=" . $ticketadult . "\n";8echo "price=" . $price12 . "\n";
    outputage=18
ticket=adult
price=12

  1. $age ← 12, $ticket ← child, $price ← 6

    1<?php2$age→ 12 = 12;3$ticket→ child = $age12 >= 18 ? "adult" : "child";4$price→ 6 = $ticketchild === "adult" ? 12 : 6;56echo "age=" . $age12 . "\n";7echo "ticket=" . $ticketchild . "\n";8echo "price=" . $price6 . "\n";
    outputage=12
ticket=child
price=6

  1. $age ← 30, $ticket ← adult, $price ← 12

    1<?php2$age→ 30 = 30;3$ticket→ adult = $age30 >= 18 ? "adult" : "child";4$price→ 12 = $ticketadult === "adult" ? 12 : 6;56echo "age=" . $age30 . "\n";7echo "ticket=" . $ticketadult . "\n";8echo "price=" . $price12 . "\n";
    outputage=30
ticket=adult
price=12

Pick Ticket and Price

  1. $age starts at 18.
  2. $age >= 18 is true, so ticket becomes adult.
  3. The second ternary sees adult.
  4. The price becomes 12. | Age | Ticket | Price | | --- | --- | --- | | 12 | child | 6 | | 18 | adult | 12 | | 30 | adult | 12 |

Exercise: ternary_choice.php

Use ternary expressions to choose child or adult ticket text and price