strpos() vs. preg_match() vs. stripos()

Lessons learned:

• strpos() is 3-16 times faster than preg_match()
• stripos() is 2-30 times slower than strpos()
• stripos() is 20-100 percent faster than preg_match() with the caseless modifier "//i"
• using a regular expression in preg_match() is not faster than using a long string
• using the utf8 modifier "//u" in preg_match() makes it 2 times slower

Here is a sample script to compare the functions with different string sizes:

<?php

function loop(){

$str_50 = str_repeat('a', 50).str_repeat('b', 50);
$str_100 = str_repeat('a', 100).str_repeat('b', 100);
$str_500 = str_repeat('a', 250).str_repeat('b', 250);
$str_1k = str_repeat('a', 1024).str_repeat('b', 1024);
$str_10k = str_repeat('a', 10240).str_repeat('b', 1024);
$str_100k = str_repeat('a', 102400).str_repeat('b', 1024);
$str_500k = str_repeat('a', 1024*500).str_repeat('b', 1024);
$str_1m = str_repeat('a', 1024*1024).str_repeat('b', 1024);

$b = 'b';
$b_10 = str_repeat('b', 10);
$b_100 = str_repeat('b', 100);
$b_1k = str_repeat('b', 1024);

echo str_replace(',', "\t", ',strpos,preg,preg U,preg S,preg regex,stripos,preg u,'.
  'preg i,preg u i,preg i regex,stripos uc,preg i uc,preg i uc regex').PHP_EOL;

foreach (array($b, $b_10, $b_100, $b_1k) as $needle) {
  foreach (array($str_50, $str_100, $str_500, $str_1k, $str_10k,
    $str_100k, $str_500k, $str_1m) as $str) {

    echo strlen($needle).'/'.strlen($str);

    $start = mt();
    for ($i=0; $i<25000; $i++) $j = strpos($str, $needle); // strpos
    echo "\t".mt($start);
    
    $regex = '!'.$needle.'!';
    $start = mt();
    for ($i=0; $i<25000; $i++) $j = preg_match($regex, $str); // preg
    echo "\t".mt($start);

    $regex = '!'.$needle.'!U';
    $start = mt();
    for ($i=0; $i<25000; $i++) $j = preg_match($regex, $str); // preg Ungreedy
    echo "\t".mt($start);

    $regex = '!'.$needle.'!S';
    $start = mt();
    for ($i=0; $i<25000; $i++) $j = preg_match($regex, $str); // preg extra analysiS
    echo "\t".mt($start);

    $regex = "!b{".strlen($needle)."}!";
    $start = mt();
    for ($i=0; $i<25000; $i++) $j = preg_match($regex, $str); // preg regex
    echo "\t".mt($start);
    
    $start = mt();
    for ($i=0; $i<25000; $i++) $j = stripos($str, $needle); // stripos
    echo "\t".mt($start);

    $regex = '!'.$needle.'!u';
    $start = mt();
    for ($i=0; $i<25000; $i++) $j = preg_match($regex, $str); // preg utf-8
    echo "\t".mt($start);

    $regex = '!'.$needle.'!i';
    $start = mt();
    for ($i=0; $i<25000; $i++) $j = preg_match($regex, $str); // preg i
    echo "\t".mt($start);

    $regex = '!'.$needle.'!ui';
    $start = mt();
    for ($i=0; $i<25000; $i++) $j = preg_match($regex, $str); // preg i utf-8
    echo "\t".mt($start);

    $regex = "!b{".strlen($needle)."}!i";
    $start = mt();
    for ($i=0; $i<25000; $i++) $j = preg_match($regex, $str); // preg i regex
    echo "\t".mt($start);

    echo PHP_EOL;
  }
  echo PHP_EOL;
}
}

function mt($start=null){
  if ($start === null) return microtime(true);
  return number_format(microtime(true)-$start, 4);
}

loop();

Running with PHP 5.4.4, 64bit, 2.3GHz (QEMU):

	strpos	preg	preg U	preg S	preg regex	stripos	preg u	preg i	preg u i	preg i regex
1/100	0.0052	0.0144	0.0147	0.0172	0.0168	0.0102	0.0180	0.0153	0.0195	0.0143
1/200	0.0058	0.0177	0.0166	0.0159	0.0143	0.0121	0.0229	0.0160	0.0236	0.0159
1/500	0.0061	0.0237	0.0246	0.0236	0.0219	0.0215	0.0394	0.0217	0.0383	0.0212
1/2048	0.0087	0.0589	0.0590	0.0580	0.0359	0.0645	0.1205	0.0499	0.1077	0.0472
1/11264	0.0221	0.2693	0.2672	0.2640	0.2443	0.3115	0.5939	0.3631	0.6803	0.3662
1/103424	0.1867	2.3432	2.3384	2.3575	2.3211	2.9327	5.3040	3.4689	6.4391	3.4750
1/513024	1.0228	11.4006	11.3530	12.0689	11.3858	14.5023	26.0701	17.2658	31.6543	16.9941
1/1049600	2.0988	23.3561	23.3382	23.3811	23.4459	30.2119	52.9937	34.9654	64.4141	35.1033
10/100	0.0055	0.0167	0.0171	0.0166	0.0148	0.0104	0.0199	0.0158	0.0215	0.0150
10/200	0.0053	0.0165	0.0155	0.0180	0.0151	0.0125	0.0222	0.0167	0.0264	0.0175
10/500	0.0065	0.0247	0.0226	0.0219	0.0179	0.0207	0.0391	0.0222	0.0376	0.0236
10/2048	0.0088	0.0590	0.0578	0.0625	0.0371	0.0649	0.1192	0.0503	0.1108	0.0484
10/11264	0.0212	0.2701	0.2652	0.2617	0.2412	0.3068	0.5838	0.3553	0.6652	0.3491
10/103424	0.1542	2.3274	2.2972	2.2938	2.2765	2.7586	5.1789	3.4096	6.3119	3.3939
10/513024	0.7236	11.4388	11.4880	11.4932	11.3312	14.1851	25.7927	17.1388	32.1902	17.5287
10/1049600	1.4951	23.4072	23.2000	23.4175	23.2439	29.6794	53.0526	34.9641	64.9861	35.9626
100/100	0.0063	0.1963	0.1956	0.0186	0.1264	0.0146	0.2922	0.2061	0.2281	0.1397
100/200	0.0060	0.0234	0.0219	0.0219	0.0212	0.0180	0.0296	0.0309	0.0422	0.0235
100/500	0.0071	0.0304	0.0297	0.0291	0.0250	0.0273	0.0452	0.0376	0.0559	0.0310
100/2048	0.0103	0.0671	0.0681	0.0676	0.0428	0.0762	0.1329	0.0665	0.1239	0.0516
100/11264	0.0210	0.2625	0.2623	0.2642	0.2422	0.3067	0.5762	0.3600	0.6774	0.3548
100/103424	0.1474	2.2864	2.2856	2.3114	2.2968	2.7858	5.2261	3.4506	6.3282	3.4003
100/513024	0.7241	11.4054	11.4286	11.3435	11.5313	14.1507	25.6885	17.1702	31.8195	17.1162
100/1049600	1.4736	23.2258	23.4724	23.2595	23.3052	29.4276	53.4051	35.2015	64.3818	34.6691
1024/100	0.0047	0.2033	0.2041	0.0517	0.1042	0.0083	0.2899	0.2092	0.2290	0.1204
1024/200	0.0049	0.0562	0.0554	0.0563	0.2900	0.0109	0.0615	0.5340	0.6496	0.3281
1024/500	0.0049	0.0647	0.0638	0.0637	1.3358	0.0181	0.0761	2.5063	3.2811	1.4076
1024/2048	0.0069	0.0955	0.0954	0.0963	0.0688	0.0887	0.1526	0.1536	0.2367	0.0809
1024/11264	0.0195	0.2974	0.2982	0.3000	0.2817	0.3375	0.6168	0.4718	0.8103	0.3845
1024/103424	0.1524	2.3356	2.3316	2.3477	2.3338	2.8351	5.2727	3.5535	6.4703	3.4583
1024/513024	0.7217	11.4283	11.5377	11.4987	11.4162	14.2862	25.8131	17.1762	33.1633	18.1542
1024/1049600	1.4657	23.3272	23.2205	23.2752	23.6812	29.1804	54.9962	34.9720	64.7529	37.1609

Running with HHVM 3.0/2014.03.27, 64bit, 2.3GHz (QEMU):

	strpos	preg	preg U	preg S	preg regex	stripos	preg u	preg i	preg u i	preg i regex
1/100	0.0028	0.0081	0.0085	0.0079	0.0079	0.0039	0.0124	0.0084	0.0125	0.0085
1/200	0.0021	0.0093	0.0094	0.0092	0.0094	0.0045	0.0167	0.0091	0.0162	0.0088
1/500	0.0021	0.0160	0.0183	0.0168	0.0121	0.0102	0.0341	0.0154	0.0309	0.0138
1/2048	0.0051	0.0541	0.0531	0.0523	0.0302	0.0374	0.1118	0.0396	0.0980	0.0394
1/11264	0.0176	0.2531	0.2537	0.2541	0.2373	0.3415	0.5682	0.3451	0.6602	0.3436
1/103424	0.1781	2.2955	2.2846	2.2814	2.2535	3.3880	5.2139	3.3744	6.2748	3.4123
1/513024	1.0425	11.3477	11.6653	11.4149	11.3018	16.9227	26.7142	17.2595	31.6541	17.2308
1/1049600	2.1241	23.2635	23.2525	23.3054	23.2256	34.9508	52.7012	34.9024	64.5221	34.9430
10/100	0.0013	0.0084	0.0084	0.0086	0.0076	0.0040	0.0126	0.0086	0.0119	0.0077
10/200	0.0014	0.0089	0.0091	0.0091	0.0088	0.0063	0.0158	0.0108	0.0167	0.0095
10/500	0.0020	0.0155	0.0158	0.0157	0.0120	0.0129	0.0308	0.0156	0.0308	0.0147
10/2048	0.0073	0.0500	0.0496	0.0505	0.0295	0.0477	0.1088	0.0410	0.1032	0.0397
10/11264	0.0169	0.2536	0.2522	0.2519	0.2312	0.4572	0.5668	0.3498	0.6614	0.3443
10/103424	0.1829	2.3130	2.2926	2.3003	2.2826	4.5526	5.2329	3.4511	6.4243	3.4623
10/513024	1.0610	11.5358	11.5248	11.4948	11.4198	22.9372	25.9165	17.0674	31.4214	16.9746
10/1049600	2.0783	23.8131	23.7319	23.1988	23.2098	46.5398	53.5480	35.4728	65.4561	35.6284
100/100	0.0012	0.0065	0.0062	0.0066	0.0058	0.0017	0.0112	0.0066	0.0101	0.0059
100/200	0.0013	0.0102	0.0101	0.0103	0.0118	0.0106	0.0172	0.0173	0.0250	0.0126
100/500	0.0018	0.0165	0.0163	0.0166	0.0149	0.0170	0.0320	0.0219	0.0383	0.0176
100/2048	0.0042	0.0505	0.0503	0.0508	0.0318	0.0510	0.1090	0.0473	0.1085	0.0432
100/11264	0.0178	0.2556	0.2535	0.2552	0.2356	0.4605	0.5690	0.3537	0.6825	0.3559
100/103424	0.1764	2.2992	2.3004	2.2966	2.2881	4.5522	5.1924	3.4346	6.2967	3.4354
100/513024	1.0296	11.3657	11.3776	11.3046	11.4125	22.5889	26.0071	16.9886	32.3710	16.9588
100/1049600	2.1064	23.4239	23.3236	23.2174	23.1929	46.4756	53.4129	34.8542	65.2457	35.4284
1024/100	0.0013	0.0116	0.0117	0.0121	0.0060	0.0009	0.0216	0.0122	0.0154	0.0058
1024/200	0.0009	0.0151	0.0151	0.0154	0.0071	0.0009	0.0279	0.0139	0.0201	0.0074
1024/500	0.0009	0.0216	0.0216	0.0219	0.0104	0.0009	0.0426	0.0190	0.0331	0.0132
1024/2048	0.0030	0.0557	0.0556	0.0562	0.0632	0.0939	0.1197	0.1173	0.1947	0.0742
1024/11264	0.0161	0.2624	0.2590	0.2588	0.2659	0.4981	0.5789	0.4164	0.7576	0.3794
1024/103424	0.1467	2.2902	2.3172	2.2994	2.2857	4.5648	5.2119	3.4726	6.3626	3.4485
1024/513024	0.7160	11.3871	11.4345	11.3034	11.4561	22.7561	25.8564	17.0333	31.4014	16.9700
1024/1049600	1.4864	23.1771	23.1033	23.4143	23.3364	47.5513	55.7561	36.7900	64.7846	35.1457