PHP Strings

Strings are sequences of characters used to store and manipulate text. PHP offers multiple ways to create strings, each with its own features and use cases. Let's explore them all!

String Syntax Options

PHP provides four ways to create strings:

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Single Quotes

Single quotes create literal strings - what you see is what you get:

<?php
$name = 'John';
echo 'Hello, $name';  // Output: Hello, $name (not parsed!)
echo 'Line 1\nLine 2';  // Output: Line 1\nLine 2 (no newline!)

// Only these escape sequences work:
echo 'It\'s working';  // \' for single quote
echo 'C:\\path\\file';  // \\ for backslash
?>

Double Quotes

Double quotes parse variables and escape sequences:

<?php
$name = "John";
$age = 25;

echo "Hello, $name!";  // Output: Hello, John!
echo "Age: $age";      // Output: Age: 25

// Escape sequences work
echo "Line 1\nLine 2";  // Actual newline
echo "Tab\there";       // Actual tab
echo "Quote: \"Hi\"";   // Escaped quotes
?>

Common Escape Sequences

Variable Interpolation

Double quotes can embed variables directly:

<?php
$name = "John";
$age = 25;

// Simple variable
echo "Name: $name";

// Array element
$user = ["name" => "Jane"];
echo "Name: {$user['name']}";  // Curly braces needed

// Object property
$person = new stdClass();
$person->name = "Bob";
echo "Name: {$person->name}";  // Curly braces needed

// Complex expressions need curly braces
echo "Next year: {$age + 1}";
?>

String Concatenation

Join strings using the dot operator (.):

<?php
$first = "Hello";
$last = "World";

// Concatenation
$combined = $first . " " . $last;
echo $combined;  // Output: Hello World

// Concatenation assignment
$message = "Hello";
$message .= " World";  // Same as: $message = $message . " World"
echo $message;  // Output: Hello World

// Multiple concatenations
$full = "My name is " . $first . " " . $last . "!";
?>

Heredoc Syntax

Heredoc is perfect for multi-line strings with variable parsing:

<?php
$name = "John";
$age = 25;

$text = <<<EOT
Hello, $name!
You are $age years old.
This is a multi-line string.
No need to escape "quotes" or 'quotes'.
EOT;

echo $text;
?>

Nowdoc Syntax

Nowdoc is like heredoc but doesn't parse variables (like single quotes):

<?php
$name = "John";

$text = <<<'EOT'
Hello, $name!
This $name will NOT be parsed.
Perfect for code examples or templates.
EOT;

echo $text;  // Output: Hello, $name! (literal)
?>

String Access by Character

Access individual characters using array-like syntax:

<?php
$str = "Hello";

echo $str[0];  // Output: H
echo $str[1];  // Output: e
echo $str[-1]; // Output: o (last character, PHP 7.1+)

// Modify characters
$str[0] = 'J';
echo $str;  // Output: Jello
?>

Common Mistakes

<?php
$user = ["name" => "John"];

echo "Name: $user['name']";  // ❌ Parse error!
echo "Name: {$user['name']}";  // ✅ Correct
?>

<?php
$text = "Hello';  // ❌ Syntax error!
$text = "Hello";  // ✅ Correct
?>

<?php
$text = <<<EOT
    Hello
    EOT;  // ❌ Parse error in PHP < 7.3 (indented)

$text = <<<EOT
Hello
EOT;  // ✅ Correct (no indentation)
?>

Exercise: String Manipulation

<?php
$recipientName = "Jane Smith";
$productName = "Premium Membership";
$price = 99.99;

$email = <<<EMAIL
Dear $recipientName,

Thank you for your interest in $productName!

Price: $$price
Special offer: Save 20% today!

Best regards,
The Team
EMAIL;

echo $email;
?>

Summary

What's Next?

Now that you know how to create and work with strings, let's explore String Functions - PHP's powerful built-in functions for manipulating, searching, and transforming strings!