substr_count

(PHP 4, PHP 5, PHP 7, PHP 8)

substr_count — Compte le nombre d'occurrences de segments dans une chaîne

Description

substr_count(
    string $haystack,
    string $needle,
    int $offset = 0,
    ?int $length = null
): int

substr_count() retourne le nombre d'occurrences de needle dans la chaîne haystack. Notez que needle est sensible à la casse.

Note:
Cette fonction ne compte pas les chaînes de caractères qui se recouvrent. Voyez l'exemple ci-dessous !

Liste de paramètres

haystack: La chaîne de caractères pour rechercher à l'intérieur
needle: La chaîne de caractères que l'on recherche
offset: Le décalage où on commence à compter. Si la position est négative, le comptage commence depuis la fin de la chaîne.
length: La taille maximale après le décalage spécifié pour rechercher la chaîne. La fonction émet une erreur si le décalage plus la taille est plus grand que la taille de haystack. Une taille négative fera que le comptage commencera à la fin de haystack.

Valeurs de retour

Cette fonction retourne un entier.

Historique

Version	Description
8.0.0	`length` est désormais nullable.
7.1.0	Ajout du support des nombres négatifs pour `offset` et `length`. `length` peut aussi être `0` maintenant.

Exemples

Exemple #1 Exemple avec substr_count()

<?php
$text = 'Ceci est un test';
echo strlen($text); // 16

echo substr_count($text, 'est'); // 2

// la chaîne de caractères est réduite à 'st un test', alors elle affiche 1
echo substr_count($text, 'est', 6);

// le texte est réduit à 'st u', alors elle affiche 0
echo substr_count($text, 'est', 6, 4);

// génère une erreur parce que 8+10 > 16
echo substr_count($text, 'est', 8, 10);


// affiche seulement 1, parce que elle ne compte pas les chaînes de caractères
// qui se recouvrent
$text2 = 'gcdgcdgcd';
echo substr_count($text2, 'gcdgcd');
?>

Voir aussi

count_chars() - Retourne des statistiques sur les caractères utilisés dans une chaîne
strpos() - Cherche la position de la première occurrence dans une chaîne
substr() - Retourne un segment de chaîne
strstr() - Trouve la première occurrence dans une chaîne

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User Contributed Notes 7 notes

down

tuxedobob ¶

8 years ago

It's worth noting this function is surprisingly fast. I first ran it against a ~500KB string on our web server. It found 6 occurrences of the needle I was looking for in 0.0000 seconds. Yes, it ran faster than microtime() could measure.

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.

down

flobi at flobi dot com ¶

18 years ago

Making this case insensitive is easy for anyone who needs this.  Simply convert the haystack and the needle to the same case (upper or lower).

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

down

tweston at bangordailynews dot com ¶

9 years ago

To account for the case that jrhodes has pointed out, we can change the line to:

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.

down

-1

jrhodes at roket-enterprises dot com ¶

15 years ago

It was suggested to use

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.

down

-1

info at fat-fish dot co dot il ¶

17 years ago

a simple version for an array needle (multiply sub-strings):
<?php

function substr_count_array( $haystack, $needle ) {
     $count = 0;
     foreach ($needle as $substring) {
          $count += substr_count( $haystack, $substring);
     }
     return $count;
}
?>

down

-1

XinfoX X at X XkarlX X-X XphilippX X dot X XdeX ¶

21 years ago

Yet another reference to the "cgcgcgcgcgcgc" example posted by "chris at pecoraro dot net":

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.

down

-5

php at blink dot at ¶

10 years ago

This will handle a string where it is unknown if comma or period are used as thousand or decimal separator. Only exception where this leads to a conflict is when there is only a single comma or period and 3 possible decimals (123.456 or 123,456). An optional parameter is passed to handle this case (assume thousands, assume decimal, decimal when period, decimal when comma). It assumes an input string in any of the formats listed below.

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>"; 
}

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