PHP Strings

A string in PHP is a sequence of characters enclosed in quotes. Strings are one of the most-used data types in PHP — used for everything from displaying HTML to querying databases.

Creating Strings

PHP supports four ways to create strings:

1. Single Quotes (Literal)

<?php
  $name = 'John Doe';
  echo 'Hello, $name!'; // Output: Hello, $name! (no interpolation)
?>

2. Double Quotes (With Interpolation)

<?php
  $name = "Alice";
  echo "Hello, $name!"; // Output: Hello, Alice!
?>

3. Heredoc

<?php
  $text = <<<EOT
  This is a multi-line
  string using heredoc.
  EOT;
  echo $text;
?>

4. Nowdoc (like single-quoted heredoc)

<?php
  $text = <<<'EOT'
  No $variable interpolation here.
  EOT;
?>

String Concatenation

Use the dot . operator to join strings:

<?php
  $first = "Codes";
  $last  = "Compiler";
  $full  = $first . $last;
  echo $full; // CodesCompiler

  $full .= " 2025"; // Append
  echo $full; // CodesCompiler 2025
?>

Essential String Functions

Function	Purpose
strlen($s)	Length of string
strtoupper($s)	Convert to UPPERCASE
strtolower($s)	Convert to lowercase
str_replace($f, $r, $s)	Replace substring
strpos($s, $n)	Find position of substring
substr($s, $start, $len)	Extract part of string
trim($s)	Remove whitespace from ends
str_word_count($s)	Count words
strrev($s)	Reverse string
str_repeat($s, $n)	Repeat string n times
ucfirst($s)	Capitalize first letter
ucwords($s)	Capitalize each word
explode($d, $s)	Split string into array
implode($d, $a)	Join array into string
sprintf($f, ...)	Format string

Live String Lab

Escape Sequences in Double-Quoted Strings

Escape	Meaning
\n	Newline
\t	Tab
\\	Backslash
\"	Double quote
\$	Dollar sign (literal)

<?php
  echo "Line 1\nLine 2\n";
  echo "Price: \$49.99\n";
  echo "Path: C:\\Users\\Admin";
?>

String Formatting with sprintf()

<?php
  $name  = "CodesCompiler";
  $price = 49.5;
  $qty   = 3;

  $msg = sprintf(
    "Order for %s: %d items at $%.2f each = $%.2f total",
    $name, $qty, $price, $qty * $price
  );
  echo $msg;
  // Order for CodesCompiler: 3 items at $49.50 each = $148.50 total
?>

PHP strings are incredibly versatile — with 100+ built-in functions, they can handle everything from basic output to complex text parsing!