PHP has a set of built-in functions that you can use to modify strings.

Upper Case

$x = "Hello World!";
echo strtoupper($x);

Lower Case

$x = "Hello World!";
echo strtolower($x);

Replace String

The PHP str_replace() function replaces some characters with some other characters in a string.

$x = "Hello World!";
echo str_replace("World", "Dolly", $x);

Reverse a String

The PHP strrev() function reverses a string.

$x = "Hello World!";
echo strrev($x);

Remove Whitespace

Whitespace is the space before and/or after the actual text, and very often you want to remove this space.

$x = " Hello World! ";
echo trim($x);

Learn more in our trim() Function Reference.

Convert String into Array

The PHP explode() function splits a string into an array.

The first parameter of the explode() function represents the "separator". The "separator" specifies where to split the string.

$x = "Hello World!";
$y = explode(" ", $x);

//Use the print_r() function to display the result:
print_r($y);

/*
Result:
Array ( [0] => Hello [1] => World! )
*/

Complete PHP String Reference

For a complete reference of all string functions, go to our complete PHP String Reference.