How to easily remove characters using RegEx and PHP

stringAndRegex.php

<?php

	# Removing symbols

	$example1 = "String with letters, numbers 0123456789 and symbols !@#$%¨&*()_+";
	echo preg_replace("/[^a-zA-Z0-9\s]/", "", $example1); // String with letters numbers 0123456789 and symbols
	
	# Remove symbols, including spaces
	
	$example2 = "String with letters, numbers 0123456789 and symbols !@#$%¨&*()_+";
	echo preg_replace("/[^a-zA-Z0-9]/", "", $example2); // Stringwithlettersnumbers0123456789andsymbols

	# Removing symbols and numbers

	$example3 = "String with letters, numbers 0123456789 and symbols !@#$%¨&*()_+";
	echo preg_replace("/[^a-zA-Z\s]/", "", $example3); // String with letters numbers and symbols

	# Removing letters and symbols

	$example4 = "String with letters, numbers 0123456789 and symbols !@#$%¨&*()_+";
	echo preg_replace("/[^0-9\s]/", "", $example4); // 0123456789

?>