PHP 7.0.6 Released

    strncmp

    (PHP 4, PHP 5, PHP 7)

    strncmp — Binary safe string comparison of the first n characters

    Description

    int strncmp ( string $str1 , string $str2 , int $len )

    This function is similar to strcmp(), with the difference that you can specify the (upper limit of the) number of characters from each string to be used in the comparison.

    Note that this comparison is case sensitive.

    Parameters

    str1

    The first string.

    str2

    The second string.

    len

    Number of characters to use in the comparison.

    Return Values

    Returns < 0 if str1 is less than str2; > 0 if str1 is greater than str2, and 0 if they are equal.

    See Also

    • strncasecmp() - Binary safe case-insensitive string comparison of the first n characters
    • preg_match() - Perform a regular expression match
    • substr_compare() - Binary safe comparison of two strings from an offset, up to length characters
    • strcmp() - Binary safe string comparison
    • strstr() - Find the first occurrence of a string
    • substr() - Return part of a string

    User Contributed Notes

    elloromtz at gmail dot com
    6 years ago
    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
    ?>
    codeguru at crazyprogrammer dot cba dot pl
    8 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
    4 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);
    ?>
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