PHP Decision Making

Decision making statements let your program choose what to do, based on a condition. For example, show “Welcome” if a user is logged in, and a login form if not. PHP has these statements: if, if...else, if...elseif...else, switch and match.

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if statement

The code inside the braces runs only when the condition is true.

<?php
$age = 20;

if ($age >= 18) {
    echo "You can vote.";
}
?>

Output:

if…else statement

<?php
$age = 15;

if ($age >= 18) {
    echo "You can vote.";
} else {
    echo "You can not vote yet.";
}
?>

Output:

if…elseif…else statement

Use it to check many conditions. PHP runs the first block whose condition is true.

<?php
$marks = 82;

if ($marks >= 90) {
    echo "Grade A";
} elseif ($marks >= 75) {
    echo "Grade B";
} elseif ($marks >= 50) {
    echo "Grade C";
} else {
    echo "Fail";
}
?>

Output:

Nested if

You can write an if inside another if. Keep it small, because too many levels are hard to read. You can also join conditions with && and ||.

<?php
$age = 25;
$hasLicense = true;

if ($age >= 18 && $hasLicense) {
    echo "You can drive.";
}
?>

Output:

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switch statement

Use switch when you compare one value with many fixed options. Do not forget break, otherwise PHP continues with the next case. The default runs if nothing matches.

<?php
$day = 3;

switch ($day) {
    case 1:
        echo "Monday";
        break;
    case 2:
        echo "Tuesday";
        break;
    case 3:
        echo "Wednesday";
        break;
    default:
        echo "Invalid day";
}
?>

Output:

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match expression (PHP 8)

The match expression is a shorter and stricter version of switch. It returns a value, uses strict comparison and needs no break. Read the full chapter: PHP match Expression.

<?php
$day = 3;

echo match ($day) {
    1 => "Monday",
    2 => "Tuesday",
    3 => "Wednesday",
    default => "Invalid day",
};
?>

Output:

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Short forms

• The ternary operator for a simple if-else in one line, see PHP Ternary Operator.
• The null coalescing operator ?? for default values.

Next chapter: PHP Loops.

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Exercises & Assignments
Write a program to check student grade based on marks
Write a program to show day of the week using switch
Write a program to calculate Electricity bill in PHP
Write a simple calculator program in PHP using switch case
Write a PHP program to check if a person is eligible to vote
Write a PHP program to check whether a number is positive, negative or zero

Interview Questions & Answers
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