strncasecmp
if length is 0 regardless what the two strings are, it will return 0
<?php
strncmp("xybc","a3234",0); // 0
strncmp("blah123","hohoho", 0); //0
?>
strncmp
(PHP 4, PHP 5)
strncmp — Comparaison binaire des n premiers caractères
Description
int strncmp
( string
$str1
, string $str2
, int $len
)
Identique à la fonction strcmp(), avec la différence
que vous pouvez spécifier le nombre maximum de caractères à utiliser pour la
comparaison de str1 avec str2
grâce au paramètre len.
Notez que cette comparaison est sensible à la casse.
Liste de paramètres
-
str1 -
La première chaîne.
-
str2 -
La seconde chaîne.
-
len -
Nombre de caractères à utiliser pour la comparaison.
Valeurs de retour
Retourne < 0 si str1
est inférieure à str2; > 0 si str1
est supérieure à str2, et 0 si les deux chaînes
sont égales.
Voir aussi
- strncasecmp() - Compare en binaire des chaînes de caractères
- preg_match() - Expression rationnelle standard
- substr_compare() - Compare deux chaînes depuis un offset jusqu'à une longueur en caractères
- strcmp() - Comparaison binaire de chaînes
- strstr() - Trouve la première occurrence dans une chaîne
- substr() - Retourne un segment de chaîne
add a note
User Contributed Notes
strncmp - [5 notes]
elloromtz at gmail dot com ¶
3 years ago
codeguru at crazyprogrammer dot cba dot pl ¶
5 years ago
I ran the following experiment to compare arrays.
1 st - using (substr($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)
)
bobvin at pillars dot net ¶
2 years ago
For checking matches at the beginning of a short string, strpos() is about 15% faster than strncmp().
Here's a benchmark program to prove it:
<?php
$haystack = "abcdefghijklmnopqrstuvwxyz";
$needles = array('abc', 'xyz', '123');
foreach ($needles as $needle) {
$times['strncmp'][$needle] = -microtime(true);
for ($i = 0; $i < 1000000; $i++) {
$result = strncmp($haystack, $needle, 3) === 0;
}
$times['strncmp'][$needle] += microtime(true);
}
foreach ($needles as $needle) {
$times['strpos'][$needle] = -microtime(true);
for ($i = 0; $i < 1000000; $i++) {
$result = strpos($haystack, $needle) === 0;
}
$times['strpos'][$needle] += microtime(true);
}
var_export($times);
?>
Anonymous ¶
3 months ago
Returns FALSE if $len is negative or NAN.
Floating point values for $len are rounded towards 0.
Anonymous ¶
11 years ago
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".