PHP If...Else...Elseif
Making decisions in your PHP code
🔀 What are Conditional Statements?
Conditional statements allow your code to make decisions and execute different code blocks based on conditions. The if...else...elseif structure helps control program flow based on true or false evaluations.
<?php
$age = 18;
if ($age >= 18) {
echo "You are an adult!";
}
?>
Output:
You are an adult!
Conditional Statement Types
if Statement
Executes code block only if the specified condition evaluates to true, otherwise skips the block entirely.
<?php
if ($x > 0) {
echo "Positive";
}
?>if...else
Provides an alternative code block to execute when the if condition is false, ensuring one path is always taken.
<?php
if ($x > 0) {
echo "Positive";
} else {
echo "Not positive";
}
?>if...elseif...else
Tests multiple conditions in sequence, executing the first matching condition's code block or the else block if none match.
<?php
if ($x > 0) {
echo "Positive";
} elseif ($x < 0) {
echo "Negative";
} else {
echo "Zero";
}
?>Nested if
Place if statements inside other if statements to create complex decision trees with multiple levels of conditions.
<?php
if ($x > 0) {
if ($x > 10) {
echo "Greater than 10";
}
}
?>🔹 Simple if Statement
Execute code only when a condition is true:
<?php
$temperature = 30;
if ($temperature > 25) {
echo "It's hot outside!";
}
echo "<br>";
$isLoggedIn = true;
if ($isLoggedIn) {
echo "Welcome back!";
}
echo "<br>";
$score = 85;
if ($score >= 80) {
echo "Great job! You passed with distinction.";
}
?>Output:
It's hot outside!
Welcome back!
Great job! You passed with distinction.
🔹 if...else Statement
Execute one block if true, another if false:
<?php
$age = 15;
if ($age >= 18) {
echo "You can vote!";
} else {
echo "You cannot vote yet.";
}
echo "<br><br>";
$hour = 14;
if ($hour < 12) {
echo "Good morning!";
} else {
echo "Good afternoon!";
}
echo "<br><br>";
$hasTicket = false;
if ($hasTicket) {
echo "Enjoy the movie!";
} else {
echo "Please buy a ticket first.";
}
?>Output:
You cannot vote yet.
Good afternoon!
Please buy a ticket first.
🔹 if...elseif...else Statement
Test multiple conditions in sequence:
<?php
$score = 75;
if ($score >= 90) {
echo "Grade: A - Excellent!";
} elseif ($score >= 80) {
echo "Grade: B - Very Good!";
} elseif ($score >= 70) {
echo "Grade: C - Good!";
} elseif ($score >= 60) {
echo "Grade: D - Pass";
} else {
echo "Grade: F - Fail";
}
echo "<br><br>";
$time = 20;
if ($time < 12) {
echo "Good morning!";
} elseif ($time < 18) {
echo "Good afternoon!";
} elseif ($time < 22) {
echo "Good evening!";
} else {
echo "Good night!";
}
?>Output:
Grade: C - Good!
Good evening!
🔹 Nested if Statements
Place if statements inside other if statements:
<?php
$age = 25;
$hasLicense = true;
if ($age >= 18) {
echo "You are old enough to drive.";
echo "<br>";
if ($hasLicense) {
echo "You can drive!";
} else {
echo "But you need a license first.";
}
} else {
echo "You are too young to drive.";
}
echo "<br><br>";
$isWeekend = true;
$weather = "sunny";
if ($isWeekend) {
if ($weather == "sunny") {
echo "Perfect day for a picnic!";
} else {
echo "Weekend, but weather is not great.";
}
} else {
echo "It's a workday.";
}
?>Output:
You are old enough to drive.
You can drive!
Perfect day for a picnic!
🔹 Combining Conditions
Use logical operators to combine multiple conditions:
<?php
$age = 25;
$income = 30000;
// AND operator (&&)
if ($age >= 18 && $income >= 25000) {
echo "Loan approved!";
} else {
echo "Loan denied.";
}
echo "<br><br>";
// OR operator (||)
$isMember = false;
$hasCoupon = true;
if ($isMember || $hasCoupon) {
echo "You get a discount!";
} else {
echo "No discount available.";
}
echo "<br><br>";
// Complex conditions
$temperature = 28;
$humidity = 70;
if ($temperature > 25 && $humidity > 60) {
echo "It's hot and humid!";
} elseif ($temperature > 25) {
echo "It's hot but dry.";
} else {
echo "Weather is comfortable.";
}
?>Output:
Loan approved!
You get a discount!
It's hot and humid!
🔹 Ternary Operator (Shorthand)
A shorter way to write simple if...else statements:
<?php
// Regular if...else
$age = 20;
if ($age >= 18) {
$status = "Adult";
} else {
$status = "Minor";
}
echo "Status: $status";
echo "<br>";
// Ternary operator (shorthand)
$age = 20;
$status = ($age >= 18) ? "Adult" : "Minor";
echo "Status: $status";
echo "<br><br>";
// More examples
$score = 85;
$result = ($score >= 60) ? "Pass" : "Fail";
echo "Result: $result";
echo "<br>";
$isLoggedIn = true;
echo $isLoggedIn ? "Welcome!" : "Please login";
?>Output:
Status: Adult
Status: Adult
Result: Pass
Welcome!