strncasecmp
I ran the following experiment to compare arrays.
1 st - using (substr($key,0,5 == "HTTP_") & 2 nd - using (!strncmp($key, 'HTTP_', 5))
I wanted to work out the fastest way to get the first few characters from a array
BENCHMARK ITERATION RESULT IS:
if (substr($key,0,5 == "HTTP_").... - 0,000481s
if (!strncmp($key, 'HTTP_', 5)).... - 0,000405s
strncmp() is 20% faster than substr() :D
<?php
// SAMPLE FUNCTION
function strncmp_match($arr)
{
foreach ($arr as $key => $val)
{
//if (substr($key,0,5 == "HTTP_")
if (!strncmp($key, 'HTTP_', 5))
{
$out[$key] = $val;
}
}
return $out;
}
// EXAMPLE USE
?><pre><?php
print_r(strncmp_match($_SERVER));
?></pre>
will display code like this:
Array
(
[HTTP_ACCEPT] => XXX
[HTTP_ACCEPT_LANGUAGE] => pl
[HTTP_UA_CPU] => x64
[HTTP_ACCEPT_ENCODING] => gzip, deflate
[HTTP_USER_AGENT] => Mozilla/4.0
(compatible; MSIE 7.0;
Windows NT 5.1;
.NET CLR 1.1.4322;
.NET CLR 2.0.50727)
[HTTP_HOST] => XXX.XXX.XXX.XXX
[HTTP_CONNECTION] => Keep-Alive
[HTTP_COOKIE] => __utma=XX;__utmz=XX.utmccn=(direct)|utmcsr=(direct)|utmcmd=(none)
)
strncmp
(PHP 4, PHP 5)
strncmp — Confronto tra stringhe sui primi n caratteri, sicuro con i dati binari
Descrizione
int strncmp
( string $str1
, string $str2
, int $len
)
Questa funzione è simile a strcmp(), con la differenza che si può specificare il limite superiore del numero di caratteri (len ) per ciascuna stringa, da utilizzare per il confronto.
Restituisce < 0 se str1 è minore di str2 ; > 0 se str1 è maggiore di str2 , e 0 se sono uguali.
Nota: questo confronto distingue tra lettere minuscole e maiuscole.
Vedere anche ereg(), strncasecmp(), strcasecmp(), substr(), stristr(), strcmp() e strstr().
add a note
User Contributed Notesstrncmp
codeguru at crazyprogrammer dot cba dot pl
24-Jan-2008 11:07
24-Jan-2008 11:07
Anonymous
17-Apr-2002 04:46
17-Apr-2002 04:46
strncmp("sample","sam",4) returns 1 because the final requirement is if one string terminates before len, then the other must also terminate at that position.
You can imagine that all your strings have one more final, invisible "termination" character. If that termination character happens to be within in len, then it must match, too.
For instance, write that termination character with, say, the sequence "\0". Then you can equivalently consider that function call as strncmp("sample\0","sam\0",4).
So, the "p" in "sample" does not match the termination character in "sam".