Как найти количество вхождений подстроки в строку

Looking to give it a challenge, I then ran it on a Mac laptop from 2010 against a 120.5MB string. For one test needle, it found 2385 occurrences in 0.0266 seconds. Another test needs found 290 occurrences in 0.114 seconds.

Long story short, if you're wondering whether this function is slowing down your script, the answer is probably not.

substr_count(strtoupper($haystack), strtoupper($needle))

substr_count ( implode( ',', $haystackArray ), $needle );

This way:

array (
  0 => "mystringth",
  1 => "atislong"
);

Becomes

mystringth,atislong

Which brings the count for $needle = "that" to 0 again.

substr_count ( implode( $haystackArray ), $needle );

instead of the function described previously, however this has one flaw.  For example this array:

array (
  0 => "mystringth",
  1 => "atislong"
);

If you are counting "that", the implode version will return 1, but the function previously described will return 0.

Your request can be fulfilled with the Perl compatible regular expressions and their lookahead and lookbehind features.

The example

$number_of_full_pattern = preg_match_all('/(cgc)/', "cgcgcgcgcgcgcg", $chunks);

works like the substr_count function. The variable $number_of_full_pattern has the value 3, because the default behavior of Perl compatible regular expressions is to consume the characters of the string subject that were matched by the (sub)pattern. That is, the pointer will be moved to the end of the matched substring.
But we can use the lookahead feature that disables the moving of the pointer:

$number_of_full_pattern = preg_match_all('/(cg(?=c))/', "cgcgcgcgcgcgcg", $chunks);

In this case the variable $number_of_full_pattern has the value 6.
Firstly a string "cg" will be matched and the pointer will be moved to the end of this string. Then the regular expression looks ahead whether a 'c' can be matched. Despite of the occurence of the character 'c' the pointer is not moved.

<?php
function substr_count_unicode($str, $substr, $caseSensitive = true, $offset = 0, $length = null) {
    if ($offset) {
        $str = substr_unicode($str, $offset, $length);
    }$pattern = $caseSensitive
        ? '~(?:'. preg_quote($substr) .')~u'
        : '~(?:'. preg_quote($substr) .')~ui';
    preg_match_all($pattern, $str, $matches);

    return isset(

$matches[0]) ? count($matches[0]) : 0;
}

function

substr_unicode($str, $start, $length = null) {
    return join('', array_slice(
        preg_split('~~u', $str, -1, PREG_SPLIT_NO_EMPTY), $start, $length));
}$s = 'Ümit yüzüm gözüm...';
print substr_count_unicode($s, 'ü');            // 3
print substr_count_unicode($s, 'ü', false);     // 4
print substr_count_unicode($s, 'ü', false, 10); // 1print substr_count_unicode($s, 'üm');           // 2
print substr_count_unicode($s, 'üm', false);    // 3
?>

function toFloat($pString, $seperatorOnConflict="f")
{
    $decSeperator=".";
    $thSeperator="";

    $pString=str_replace(" ", $thSeperator, $pString);

    $firstPeriod=strpos($pString, ".");
    $firstComma=strpos($pString, ",");
    if($firstPeriod!==FALSE && $firstComma!==FALSE) {
        if($firstPeriod<$firstComma) {
            $pString=str_replace(".", $thSeperator, $pString);
            $pString=str_replace(",", $decSeperator, $pString);
        }
        else {
            $pString=str_replace(",", $thSeperator, $pString);
        }
    }
    else if($firstPeriod!==FALSE || $firstComma!==FALSE) {
        $seperator=$firstPeriod!==FALSE?".":",";
        if(substr_count($pString, $seperator)==1) {
            $lastPeriodOrComma=strpos($pString, $seperator);
            if($lastPeriodOrComma==(strlen($pString)-4) && ($seperatorOnConflict!=$seperator && $seperatorOnConflict!="f")) {
                $pString=str_replace($seperator, $thSeperator, $pString);
            }
            else {
                $pString=str_replace($seperator, $decSeperator, $pString);
            }
        }
        else {
            $pString=str_replace($seperator, $thSeperator, $pString);
        }
    }
    return(float)$pString;
}

function testFloatParsing() {
    $floatvals = array(
        "22 000",
        "22,000",
        "22.000",
        "123 456",
        "123,456",
        "123.456",
        "22 000,76",
        "22.000,76",
        "22,000.76",
        "22000.76",
        "22000,76",
        "1.022.000,76",
        "1,022,000.76",
        "1,000,000",
        "1.000.000",
        "1022000.76",
        "1022000,76",
        "1022000",
        "0.76",
        "0,76",
        "0.00",
        "0,00",
        "1.00",
        "1,00",
        "-22 000,76",
        "-22.000,76",
        "-22,000.76",
        "-22 000",
        "-22,000",
        "-22.000",
        "-22000.76",
        "-22000,76",
        "-1.022.000,76",
        "-1,022,000.76",
        "-1,000,000",
        "-1.000.000",
        "-1022000.76",
        "-1022000,76",
        "-1022000",
        "-0.76",
        "-0,76",
        "-0.00",
        "-0,00",
        "-1.00",
        "-1,00"
    );

        echo "<table>
        <tr>
            <th>String</th>
            <th>thousands</th>
            <th>fraction</th>
            <th>dec. if period</th>
            <th>dec. if comma</th>
        </tr>";

            foreach ($floatvals as $fval) {
        echo "<tr>";
        echo "<td>" . (string) $fval . "</td>";

                echo "<td>" . (float) toFloat($fval, "") . "</td>";
        echo "<td>" . (float) toFloat($fval, "f") . "</td>";
        echo "<td>" . (float) toFloat($fval, ".") . "</td>";
        echo "<td>" . (float) toFloat($fval, ",") . "</td>";
        echo "</tr>";
    }
    echo "</table>";
}

<?php
substr_count ( implode( $haystackArray ), $needle );
?>

Please take careful consideration of possible edge cases with that regex, in example:

$url = 'http://w3.host.tld/path/to/file/..../file.extension';
$url = 'http://w3.host.tld/path/to/file/../file.extension?malicous=....';

This would cause a infinite loop and for example be a possible entry point for a denial of service attack. A correct fix would require additional code, a quick hack would be just adding a additional check, without clarity or performance in mind:

...
$i = 0;
while (substr_count($url, '../') && ++$i < strlen($url))
...

-Chris