Strings & Regular Expressions - Concepts
Explore the key concepts of strings & regular expressions with practical examples and exercises.
45 min•By Priygop Team•Last updated: Feb 2026
Introduction to Strings & Regular Expressions
In this section, we cover the fundamental aspects of strings & regular expressions. You'll learn core concepts, see real-world examples, and understand how to apply them in your projects.
Key Concepts
- Understanding the core principles of strings & regular expressions
- Practical applications and real-world use cases
- Step-by-step implementation guides
- Common patterns and best practices
- Tips for debugging and troubleshooting
- Performance optimization techniques
Strings & Regular Expressions - Code Example
Example
<?php
$str = "Hello, World!";
echo strlen($str) . "\n";
echo strtoupper($str) . "\n";
echo strtolower($str) . "\n";
echo str_replace("World", "PHP", $str) . "\n";
echo substr($str, 0, 5) . "\n";
echo strpos($str, "World") . "\n";
// Regular expressions
$email = "user@example.com";
if (preg_match('/^[\w.+-]+@[\w-]+\.[\w.]+$/', $email)) {
echo "Valid email\n";
}
$text = "Price: $25.99 and $13.50";
preg_match_all('/\$[\d.]+/', $text, $matches);
echo "Prices: " . implode(", ", $matches[0]) . "\n";
?>Try It Yourself: Strings & Regular Expressions
Try It Yourself: Strings & Regular ExpressionsJavaScript⚠ 1 error
⚠ Syntax Issues (1)
✕
Line 1: JS Error: Unexpected token '<'
💡 Missing or extra {}()[] or operator near the error.
JavaScript Editor
✕ 1 errorTab = 2 spaces
JavaScript|17 lines|478 chars|1 error, 0 warnings
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