String is probably the most used data type in PHP as it is a templating language in nature. PHP string counts for a big part of your coding. Not to mention most of us use PHP to do what it does the best — serving web pages, involving a lot of strings all the way.
Okay, let’s cut the bullshit. To get or count the length of a php string, you need the strlen() function.
<?php
$str = 'Hi.';
$length = strlen($str); // $length equals to 3 as there are 3 characters in the string 'Hi.'
?>A slightly better approach, is to examine the existence of the nth character of a string to determine the length of a string:
if (isset($str[5])) { // $str[5] is the 6th character of $str
echo 'This string is at least 6 bytes in size (6 characters long).';
}The reasoning of this is that strlen is a function while isset is a language construct which should come faster. Not to mention that intuitively, counting the length of a string from the first byte to the last takes intrinsically more time than the determination of the existence of just one byte.
function benchmark_function($fn,$args=null)
{
if(!is_callable($fn))
{
trigger_error(“Call to undefined function $fn()”,E_USER_ERROR);
}
$t = microtime(true);
$r = call_user_func_array($fn,$args);
return array(“time”=>(microtime(true)-$t),”returned”=>$r,”fn”=>$fn);
}
function bit_round($n,$u=false)
{
return ($n+(float)$u)>>1;
}
function get_len_loop($s)
{
while($s[$i++]){}
return $i-1;
}
$t = “kejhkhfkewkfhkwjfjrw”;
echo var_dump(benchmark_function(“strlen”,$t)).””;
echo var_dump(benchmark_function(“get_len_loop”,$t)).””;
$tm = microtime(true);
$r = isset($t[9]);
$a = array(“time”=>(microtime(true)-$tm),”returned”=>$r,”fn”=>$fn);
echo var_dump($a);
output:
run 1:
array(3) { [“time”]=> float(3.814697265625E-6) [“returned”]=> int(20) [“fn”]=> string(6) “strlen” }
array(3) { [“time”]=> float(1.5020370483398E-5) [“returned”]=> int(20) [“fn”]=> string(12) “get_len_loop” }
array(3) { [“time”]=> float(4.0531158447266E-6) [“returned”]=> bool(true) [“fn”]=> string(5) “isset” }
run 2:
array(3) { [“time”]=> float(3.0994415283203E-6) [“returned”]=> int(20) [“fn”]=> string(6) “strlen” }
array(3) { [“time”]=> float(1.5020370483398E-5) [“returned”]=> int(20) [“fn”]=> string(12) “get_len_loop” }
array(3) { [“time”]=> float(4.0531158447266E-6) [“returned”]=> bool(true) [“fn”]=> string(5) “isset” }
run 3:
array(3) { [“time”]=> float(4.0531158447266E-6) [“returned”]=> int(20) [“fn”]=> string(6) “strlen” }
array(3) { [“time”]=> float(1.1920928955078E-5) [“returned”]=> int(20) [“fn”]=> string(12) “get_len_loop” }
array(3) { [“time”]=> float(3.0994415283203E-6) [“returned”]=> bool(true) [“fn”]=> string(5) “isset” }
run 4:
array(3) { [“time”]=> float(3.814697265625E-6) [“returned”]=> int(20) [“fn”]=> string(6) “strlen” }
array(3) { [“time”]=> float(1.4066696166992E-5) [“returned”]=> int(20) [“fn”]=> string(12) “get_len_loop” }
array(3) { [“time”]=> float(4.0531158447266E-6) [“returned”]=> bool(true) [“fn”]=> string(5) “isset” }
run 5:
array(3) { [“time”]=> float(2.8610229492188E-6) [“returned”]=> int(20) [“fn”]=> string(6) “strlen” }
array(3) { [“time”]=> float(1.5020370483398E-5) [“returned”]=> int(20) [“fn”]=> string(12) “get_len_loop” }
array(3) { [“time”]=> float(2.8610229492188E-6) [“returned”]=> bool(true) [“fn”]=> string(5) “isset” }
it turns out that making a while inside a function is waaaaaaay faster!!!
tested on:
http://writecodeonline.com/php/