Useful String Functions in PHP (With Detailed Examples & Output)

Looking to learn PHP string functions in a simple way?

You’re in the right place! PHP offers a powerful set of string functions that help you manipulate and format text. Whether you’re validating form input, generating excerpts, or parsing data—these functions make your job easier.

Why Are PHP String Functions Important?

String functions in PHP allow you to:

  • Measure string length
  • Change string case (uppercase/lowercase)
  • Extract or replace parts of a string
  • Split strings into arrays
  • Remove unwanted spaces

Mastering these will save you time and improve code quality.

Most Useful String Functions in PHP

Here’s a list of commonly used PHP string functions every developer should know:

  1. strlen()
  2. strtoupper()
  3. strtolower()
  4. ucfirst()
  5. ucwords()
  6. substr()
  7. strpos()
  8. str_replace()
  9. trim()
  10. explode()

Let’s break each one down in detail

1. strlen() – Get the Length of a String

strlen() returns the total number of characters in a string, including spaces and special characters.

Syntax :

strlen(string $string): int

Example :

<?php
$text = "Hello World!";
echo strlen($text);
?>

Output :

12

Commonly used for checking input lengths like usernames, passwords, etc.

2. strtoupper() – Convert Entire String to Uppercase

strtoupper() converts every character of a string to uppercase.

Syntax :

strtoupper(string $string): string

Example :

<?php
echo strtoupper("php is awesome!");
?>

Output :

PHP IS AWESOME!

3. strtolower() – Convert Entire String to Lowercase

strtolower() changes all characters in the string to lowercase.

Syntax :

strtolower(string $string): string

Example :

<?php echo strtolower("HELLO PHP"); ?>

Output:

hello php

4. ucfirst() – Uppercase First Letter of a String

ucfirst() capitalizes the first character of a string.

Syntax :

ucfirst(string $string): string

Example :

<?php
echo ucfirst("hello php!");
?>

Output :

Hello php!

5. ucwords() – Uppercase First Letter of Each Word

ucwords() capitalizes the first letter of every word in the string.

Syntax :

ucwords(string $string): string

Example :

<?php
echo ucwords("learn php with examples");
?>

Output :

Learn Php With Examples

6. substr() – Extract a Portion of a String

substr() returns a part of the string starting at a specified position.

Syntax :

substr(string $string, int $start, int $length): string

Example :

<?php
echo substr("Learn PHP Programming", 6, 3);
?>

Output :

PHP

7. strpos() – Find Position of a Substring

strpos() finds the position of the first occurrence of a substring in a string.

Syntax :

strpos(string $haystack, string $needle): int|false

Example :

<?php
echo strpos("Welcome to PHP", "PHP");
?>

Output :

11

If the substring is not found, it returns false.

8. str_replace() – Replace Text in a String

str_replace() replaces occurrences of a word or phrase with another.

Syntax :

str_replace(mixed $search, mixed $replace, mixed $subject): mixed

Example :

<?php
echo str_replace("Python", "PHP", "I love Python");
?>

Output :

I love PHP

9. trim() – Remove Extra Whitespaces

trim() removes whitespace and other predefined characters from both sides of a string.

Example :

<?php
echo trim("   Hello PHP!   ");
?>

Output :

Hello PHP!

10. explode() – Split String into Array

explode() breaks a string into an array using a delimiter.

Syntax :

explode(string $separator, string $string): array

Example :

<?php
$colors = explode(",", "red,green,blue");
print_r($colors);
?>

Output :

Array
(
    [0] => red
    [1] => green
    [2] => blue
)

These useful PHP string functions make your code cleaner, faster, and easier to maintain. Mastering these functions is essential for handling dynamic content, user inputs, and data formatting in real-world applications.

Whether you’re validating inputs, displaying formatted data, or transforming user-submitted content, these PHP string functions are must-know tools in your development toolbox.