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 — Comparación de los n primeros caracteres de cadenas, con seguridad binaria
Descripción
int strncmp
( string $cadena1
, string $cadena2
, int $longitud
)
Esta función es similar a strcmp(), con la diferencia que se puede especificar el (límite superior del) número de caractares (longitud ) de cada cadena que se usarán en la comparación.
Devuelve < 0 si cadena1 es menor que cadena2 ; > 0 si cadena1 es mayor que cadena2 y 0 si son iguales.
Nótese que esta comparación es sensible a mayúsculas y minúsculas.
Vea también ereg(), strncasecmp(), strcasecmp(), substr(), stristr(), strcmp() y strstr().
add a note
User Contributed Notesstrncmp
codeguru at crazyprogrammer dot cba dot pl
24-Jan-2008 07:07
24-Jan-2008 07:07
Anonymous
17-Apr-2002 11:46
17-Apr-2002 11:46
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".