Efficiency comparison of string functions strtr, str_replace and preg_replace in PHP

The following compares the efficiency of strtr, str_replace and preg_replace:

<?php
/**
* strtr, str_replace和preg_replace的效率对比分析
* edit bbs.it-home.org
**/
$str = 
'111111110000000000000000000000000000000111000001000100010000010010000010010000010100000010
'; 
$str = str_repeat($str, 1); 
$pattern1 = array('12345'=>'', '67891'=>''); 
$pattern2 = array('a'=>'', '1234567890'=>''); 
$pattern3 = '/12345|67891/'; 
$pattern4 = '/a|1234567890/'; 
$pattern5 = array('12345', '67891'); 
$pattern6 = array('a', '1234567890'); 
$t = microtime(true); 
for($i=0; $i<10000; $i++) 
{
strtr($str, $pattern1); 
} 
echo microtime(true)-$t, "/n"; //0.21915886878967 0.47268319129944 
$t = microtime(true); 
for($i=0; $i<10000; $i++) 
{
strtr($str, $pattern2); 
} 
echo microtime(true)-$t, "/n"; //0.4768660068512 2.7257590293884 
$t = microtime(true); 
for($i=0; $i<10000; $i++) 
{
preg_replace($pattern3, '', $str); 
} 
echo microtime(true)-$t, "/n"; //0.30504012107849 1.0864448547363 
$t = microtime(true); 
for($i=0; $i<10000; $i++) 
{
preg_replace($pattern4, '', $str); 
} 
echo microtime(true)-$t, "/n"; //0.30298089981079 1.117014169693 
$t = microtime(true); 
for($i=0; $i<10000; $i++) 
{
str_replace($pattern5, '', $str); 
} 
echo microtime(true)-$t, "/n"; //0.18029189109802 0.22510504722595 
$t = microtime(true); 
for($i=0; $i<10000; $i++) 
{
str_replace($pattern6, '', $str); 
} 
echo microtime(true)-$t, "/n"; //0.18104100227356 0.23055601119995 
//说明：当str_repeat的第二个参数为1时输出第一个数字，当为8时输出第二个数字 
?>

Judging from the output results, the overall performance of str_replace is better than strtr and preg_replace. The reason can be seen from looking at the source code of str_replace (http://code.google.com/p/cyy0523xc/source/browse/trunk/php/str_replace%E6%BA%90%E7%A0%81.c) , when str_replace(array search, string|array replace, string subject) is executed, it will loop through each element of the search in order (not according to the subscript or other order, this is related to the underlying implementation of the array) , then go to the subject to match, and if found, replace it with the corresponding replace. This will indeed be more efficient than strtr, because there will be one more loop from the maximum length of the subscript to the minimum length. If the length of the subscript string changes significantly at this time, and the subject string is relatively long, the overhead here will be It is also relatively large. However, there is something we need to pay attention to in the implementation of str_replace, that is, it will not give priority to the largest match like strtr. For example:

<?php
str_replace(array('ab', 'abc'), '1', 'abcd');
?>

If strtr is used, our output result will be "1d" because strtr will achieve the maximum match. However, str_replace will output "1cd", because 'ab' is ranked before "abc" in the search string, so 'ab' will be replaced with '1' first.

Summarize the usage of the three functions: 1. str_replace: This should be used as the preferred method for string replacement. One thing to note is to put the element you most want to match in front.

2, strtr: strtr is also very efficient when replacing short strings, but the difference in the subscript length of the search array also has a greater impact on efficiency. Also, it is best not to use strtr(string, string, string) (it is easy to produce garbled characters for non-single-byte characters).

3, preg_replace: You can use regular matching, the function is definitely the strongest, but the efficiency is a little lower.