My PHP Performance Benchmarks

PHP version 5.2.13 is running on this server.

Check if a String is empty

Method	Undefined	Null	False	Empty string	String "0"	String "1"	Long string	Summary	Index
`if (!$var)`	2.4 ms	0.4 ms	0.4 ms	0.4 ms	0.4 ms	0.2 ms	0.2 ms	4.3 ms	136
`if (empty($var))`	0.4 ms	0.5 ms	0.5 ms	0.5 ms	0.5 ms	0.3 ms	0.3 ms	3.1 ms	100
`if ($var == "")`	2.6 ms	0.4 ms	0.4 ms	0.5 ms	0.5 ms	0.5 ms	38.0 ms	43.0 ms	1371
`if ("" == $var)`	2.6 ms	0.5 ms	0.5 ms	0.5 ms	0.3 ms	0.3 ms	0.4 ms	5.1 ms	161
`if ($var === "")`	2.1 ms	0.2 ms	0.2 ms	0.5 ms	0.2 ms	0.2 ms	0.2 ms	3.5 ms	111
`if ("" === $var)`	2.1 ms	0.2 ms	0.2 ms	0.4 ms	0.2 ms	0.2 ms	0.2 ms	3.5 ms	112
`if (strcmp($var, "") == 0)`	3.7 ms	1.5 ms	1.8 ms	1.3 ms	1.2 ms	1.6 ms	1.1 ms	12.3 ms	391
`if (strcmp("", $var) == 0)`	3.8 ms	1.6 ms	1.7 ms	1.3 ms	1.1 ms	1.1 ms	1.1 ms	11.8 ms	375
`if (strlen($var) == 0)`	3.4 ms	1.2 ms	1.3 ms	1.0 ms	0.8 ms	0.8 ms	0.8 ms	9.4 ms	301
`if (!strlen($var))`	3.2 ms	1.1 ms	1.3 ms	0.9 ms	0.7 ms	0.8 ms	0.7 ms	8.8 ms	280

My conclusion: In most cases, use empty() because it does not trigger a warning when used with undefined variables. Note that empty("0") returns true. Use strlen() if you want to detect "0". Try to avoid == at all because it may cause strange behaviour (e.g. "9a" == 9 returns true). Prefer === over == and !== over != if possible because it does compare the variable types in addition to the contents.

Compare two Strings

Method	Equal	First character not equal	Last character not equal	Summary	Index
`$a == $b`	2.1 ms	1.4 ms	1.9 ms	5.3 ms	100
`!strcmp($a, $b)`	3.9 ms	3.2 ms	3.8 ms	10.8 ms	203
`strcmp($a, $b) == 0`	3.9 ms	3.3 ms	3.9 ms	11.2 ms	210
`strcmp($a, $b) === 0`	3.7 ms	3.5 ms	3.8 ms	11.0 ms	205
`strcasecmp($a, $b) === 0`	8.0 ms	3.1 ms	8.0 ms	19.0 ms	356

My conclusion: ?

Check if a String contains another String

Method	Not found	Found at the start	Found in the middle	Found at the end	Summary	Index
`strstr($haystack, $needle)`	1.0 ms	1.0 ms	1.1 ms	1.1 ms	4.2 ms	102
`strpos($haystack, $needle) !== false`	0.9 ms	1.0 ms	1.1 ms	1.1 ms	4.1 ms	100
`strstr($haystack, $needle) !== false`	0.9 ms	1.1 ms	1.2 ms	1.2 ms	4.4 ms	108
`stristr($haystack, $needle)`	1.8 ms	2.2 ms	2.8 ms	2.1 ms	8.9 ms	217
`preg_match("/$needle/", $haystack)`	1.9 ms	1.8 ms	2.0 ms	2.2 ms	7.9 ms	194
`preg_match("/$needle/i", $haystack)`	1.9 ms	1.9 ms	2.1 ms	2.3 ms	8.2 ms	200
`preg_match("/$needle/S", $haystack)`	1.9 ms	1.8 ms	2.1 ms	2.2 ms	8.0 ms	196
`ereg($needle, $haystack)`	2.2 ms	2.2 ms	9.5 ms	16.8 ms	30.6 ms	748

My conclusion: It does not matter if you use strstr() or strpos(). Use the preg…() functions only if you need the power of regular expressions. Never use the ereg…() functions.

Check if a String starts with another String

Method	Not found	Found at the start	Found in the middle	Found at the end	Summary	Index
`strncmp($haystack, $needle, strlen($needle)) === 0`	1.5 ms	1.4 ms	1.4 ms	1.4 ms	5.7 ms	149
`strncmp($haystack, "Test", 4) === 0`	1.0 ms	1.0 ms	1.0 ms	1.0 ms	4.0 ms	103
`strncasecmp($haystack, $needle, strlen($needle)) === 0`	1.4 ms	1.4 ms	1.4 ms	1.4 ms	5.6 ms	146
`strpos($haystack, $needle) === 0`	1.0 ms	0.9 ms	1.0 ms	1.0 ms	3.8 ms	100
`substr($haystack, 0, strlen($needle)) === $needle`	1.6 ms	1.6 ms	1.6 ms	1.6 ms	6.4 ms	165
`strcmp(substr($haystack, 0, strlen($needle)), $needle) === 0`	2.2 ms	2.2 ms	2.3 ms	2.2 ms	8.9 ms	232
`preg_match("/^" . preg_quote($needle, "/") . "/", $haystack)`	2.9 ms	3.1 ms	2.9 ms	2.9 ms	11.8 ms	306

My conclusion: strpos() is very fast and can be used in almost all cases. strncmp() is good if you are looking for a constant length needle.

Check if a String ends with another String

Method	Not found	Found at the start	Found in the middle	Found at the end	Summary	Index
`substr($haystack, strlen($haystack) - strlen($needle)) === $needle`	2.0 ms	2.0 ms	2.3 ms	2.3 ms	8.5 ms	136
`substr($haystack, -strlen($needle)) === $needle`	1.6 ms	1.6 ms	1.6 ms	1.6 ms	6.3 ms	100
`strcmp(substr($haystack, -strlen($needle)), $needle) === 0`	2.2 ms	2.2 ms	2.2 ms	2.2 ms	8.8 ms	141
`preg_match("/" . preg_quote($needle, "/") . "$/", $haystack)`	3.3 ms	3.7 ms	3.6 ms	3.7 ms	14.2 ms	227

My conclusion: Using substr() with a negative position is a good trick.

Replace a String inside another String

Method	Not found	Found at the start	Found in the middle	Found at the end	Summary	Index
`str_replace($search, $replace, $subject)`	1.8 ms	1.9 ms	1.8 ms	1.9 ms	7.5 ms	100
`preg_replace("/$search/", $replace, $subject)`	2.9 ms	3.2 ms	3.4 ms	3.3 ms	12.8 ms	171
`preg_replace("/$search/S", $replace, $subject)`	2.7 ms	3.3 ms	3.3 ms	3.2 ms	12.5 ms	167
`ereg_replace($search, $replace, $subject)`	3.4 ms	5.6 ms	12.1 ms	19.0 ms	40.1 ms	535

My conclusion: Never use the ereg…() functions.

Trim Characters from the Beginning and End of a String

Method	Not found	Found at start	Found at end	Found at both sides	Summary	Index
`trim($string, ",")`	0.2 ms	0.2 ms	0.2 ms	0.2 ms	0.8 ms	100
`preg_replace('/^,\|,$/', "", $string)`	6.8 ms	6.9 ms	6.8 ms	6.9 ms	27.4 ms	3409
`preg_replace('/^,\|,$/m', "", $string)`	11.4 ms	11.3 ms	11.3 ms	11.3 ms	45.3 ms	5637
`preg_replace('/^,+\|,+$/', "", $string)`	0.5 ms	0.5 ms	0.5 ms	0.5 ms	1.9 ms	232
`preg_replace('/^,+\|,+$/m', "", $string)`	0.4 ms	0.4 ms	0.5 ms	0.5 ms	1.8 ms	224
`preg_replace('/^,+/', "", preg_replace('/,+$/', "", …))`	0.8 ms	0.8 ms	0.8 ms	0.8 ms	3.1 ms	381

My conclusion: Always benchmark your regular expressions! In this case, with .* you also replace nothing with nothing which takes time because there is a lot of “nothing” in every string.

Split a String into an Array

Method	Empty string	Single occurrence	Multiple occurrences	Summary	Index
`explode(",", $string)`	1.1 ms	1.2 ms	7.6 ms	10.0 ms	100
`split(",", $string)`	1.2 ms	1.9 ms	40.4 ms	43.5 ms	436
`preg_split("/,/", $string)`	1.6 ms	1.9 ms	11.4 ms	14.8 ms	149
`preg_match_all('/[^,]+/', $string, $matches)`	2.1 ms	3.5 ms	18.5 ms	24.1 ms	242

My conclusion: Don't use split(). It's deprecated in PHP 5.3 and will be removed in PHP 6.

Loop a numerical indexed Array of Strings

Method	Summary	Index
`for ($i = 0; $i < count($array); $i++)`	43.9 ms	6044
`for ($i = 0, $count = count($array); $i < $count; $i++)`	1.0 ms	139
`for ($i = count($array) - 1; $i >= 0; $i--)`	1.0 ms	131
`for ($i = count($array) - 1; $i >= 0; --$i)`	0.9 ms	129
`$i = count($array); while ($i--)`	0.7 ms	100

My conclusion: count() is horribly slow. Always precalculate it, if possible.

Get Elements from an Array

Method	Summary	Index
`$array[0]`	33.5 ms	100
`$array['key']`	34.4 ms	103

My conclusion: I like associative arrays.

The single vs. double Quotes Myth

Method	Summary	Index
`'contains no dollar signs'`	0.7 ms	108
`"contains no dollar signs"`	0.7 ms	110
`'$variables $are $not $replaced'`	0.6 ms	100
`"\$variables \$are \$not \$replaced"`	0.6 ms	103
`"$variables $are $replaced"`	7.5 ms	1235
`$variables . ' ' . $are . ' ' . $replaced`	9.1 ms	1497
`$variables . " " . $are . " " . $replaced`	8.8 ms	1444

My conclusion: It does not matter if you use single or double quotes at all. The inclusion of variables has a measurable effect, but that's independent from the quotes.