Convert lib_string to string w/o Regex - php

Question

I need to convert lib_someString to someString inside a block of text using str_replace [not regex].
Here's an example to give an exact sense what I mean: lib_12345 => 12345. I need to do this for a bunch of instances in a block of text.
Below is my attempt. Problem I'm getting is that my function is not doing anything (I just get lib_id returned).
function extractLibId($val){ // function to get the "12345" in the above example
$lclRetVal = substr($val, 5, strlen($val));
return $lclRetVal;
}
function Lib($text){ // does the replace for all lib_ instances in the text
$lclVar = "lib_";
$text = str_replace($lclVar, "<a href='".extractLibId($lclVar)."'>".extractLibId($lclVar)."</a>", $text);
return $text;
}

Answer 1

Regexp gonna be faster and more clear, you will have no need to call your function for every possible 'lib_' string:
function Lib($text) {
$count = null;
return preg_replace('/lib_([0-9]+)/', '$1', $text, -1, $count);
}
$text = 'some text lib_123123 goes here lib_111';
$text = Lib($text);
Without regexp, but every time Lib2 will be called somewhere will die cute kitten:
function extractLibId($val) {
$lclRetVal = substr($val, 4);
return $lclRetVal;
}
function Lib2($text) {
$count = null;
while (($pos = strpos($text, 'lib_')) !== false) {
$end = $pos;
while (!in_array($text[$end], array(' ', ',', '.')) && $end < strlen($text))
$end++;
$sub = substr($text, $pos, $end - $pos);
$text = str_replace($sub, ''.extractLibId($sub).'', $text);
}
return $text;
}
$text = 'some text lib_123123 goes here lib_111';
$text = Lib2($text);
Use preg_replace.

Answer 2

Although it is possible to do what you need without regular expressions, you say you don't want to use them because of performance reasons. I doubt the other solution will be faster, so here is a simple regex to benchmark against:
echo preg_replace("/lib_(\w+)/", '$1', $str);
As shown here: http://codepad.org/xGj78r9r

Answer 3

Ignoring how ridiculous area of optimizing this is, even the simplest implementation with minimal validation already takes only 33% less time than a regex
<?php
function uselessFunction( $val ) {
if( strpos( $val, "lib_" ) !== 0 ) {
return $val;
}
$str = substr( $val, 4 );
return "{$str}";
}
$l = 100000;
$now = microtime(TRUE);
while( $l-- ) {
preg_replace( '/^lib_(.*)$/', "$1", 'lib_someString' );
}
echo (microtime(TRUE)-$now)."\n";
//0.191093
$l = 100000;
$now = microtime(TRUE);
while( $l-- ) {
uselessFunction( "lib_someString" );
}
echo (microtime(TRUE)-$now);
//0.127598
?>

Answer 4

If you're restricted from using a regex, you're going to have difficult time searching for a string you describe as "someString", i.e. not precisely known in advance. If you know the string is exactly lib_12345, for example, then set $lclVar to that string. On the other hand, if you don't know the exact string in advance, you'll have to use a regex via preg_replace() or a similar function.