<?php

$subject = "+-&&||!( ){ } [ ]^\"~*?:/";
$result = preg_replace('%([+\-&|!(){}[\]^"~*?:/]+)%', '\\\\$1', $subject);
echo "Result 1: ". $result ."\n";


$subject = "+-&&||!( ){ } [ ]^\"~*?:/";
$result = preg_replace('%[^\w]+)%', '\\\\$1', $subject);
echo "Result 2: ". $result ."\n";