PHP Standard Library: Complete Overview

PHP is one of the most popular languages for web development, and its standard library provides developers with a powerful set of ready-made solutions. In this overview, we will examine in detail the main components of the PHP standard library, which allow solving tasks from simple string processing to complex work with databases and network protocols.

1. Working with Arrays (array_*)

Functions for working with arrays are among the most in-demand in PHP. The standard library contains over 80 functions for array manipulation.

array_map() — applies a callback to all elements of an array
array_filter() — filters array elements using a callback
array_reduce() — iteratively reduces an array to a single value
array_merge() — merges one or more arrays
array_search() — searches for a value in an array and returns the key

<?php$numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

// Filtering even numbers$even = array_filter($numbers, function($n) {    return $n % 2 === 0;});

// Doubling each element$doubled = array_map(function($n) {    return $n * 2;}, $numbers);

// Sum of all elements$sum = array_reduce($numbers, function($carry, $item) {    return $carry + $item;}, 0);

echo "Even: " . implode(', ', $even) . "<br>";echo "Doubled: " . implode(', ', $doubled) . "<br>";echo "Sum: $sum";?>

2. String Functions

PHP offers an extensive set of functions for string processing, including work with multibyte encodings via the mbstring extension.

strlen() / mb_strlen() — string length
strpos() / mb_strpos() — substring search
substr() / mb_substr() — substring extraction
str_replace() — substring replacement
explode() / implode() — string splitting/joining
trim() — removing whitespace from beginning and end

<?php$text = "  Hello, world! PHP is great.  ";

// Removing extra whitespace$clean = trim($text);

// Substring replacement$replaced = str_replace("great", "awesome", $clean);

// Splitting string into words$words = explode(" ", $replaced);

// Getting first 10 characters$first10 = mb_substr($clean, 0, 10, 'UTF-8');

echo "Cleaned text: '$clean'<br>";echo "With replacement: '$replaced'<br>";echo "First 10 characters: '$first10'<br>";echo "Number of words: " . count($words);?>

3. Working with Dates and Time (DateTime)

The DateTime class and its derivatives provide an object-oriented interface for working with dates.

<?php// Creating a date object$date = new DateTime('2024-12-25 10:30:00');

// Formattingecho $date->format('Y-m-d H:i:s') . "<br>";

// Adding an interval$date->add(new DateInterval('P10D')); // +10 daysecho "In 10 days: " . $date->format('Y-m-d') . "<br>";

// Difference between dates$now = new DateTime();$diff = $now->diff($date);echo "Days remaining until the date: {$diff->days} days";

// Working with time zones$date->setTimezone(new DateTimeZone('America/New_York'));echo "<br>In New York: " . $date->format('Y-m-d H:i:s');?>