substr_count

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

substr_count — Cuenta el número de apariciones del substring

Descripción

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

substr_count() devuelve el número de veces en que el substring needle aparece en el string haystack. Por favor nótese que needle es sensible a mayúsculas y minúsculas.

Nota:
Esta función no cuenta las subcadenas que se traslapan. Véase el ejemplo de abajo!

Parámetros

haystack: El string dentro del cual buscar
needle: El substring a buscar
offset: El desplazamiento por dónde empezar a contar
length: La longitud máxima después del desplazamiento especificado para buscar el substring. Se emite una advertencia si offset más length es mayor que la longitud de haystack.

Valores devueltos

Esta función devuelve un integer.

Historial de cambios

Versión	Descripción
5.1.0	Los parámetros `offset` y `length` fueron agregados

Ejemplos

Ejemplo #1 Ejemplo de substr_count()

<?php
$text = 'This is a test';
echo strlen($text); // 14

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

// el string es reducido a 's is a test', así que muestra 1
echo substr_count($text, 'is', 3);

// el texto es reducido a 's i', así que muestra 0
echo substr_count($text, 'is', 3, 3);

// genera una advertencia debido a que 5+10 > 14
echo substr_count($text, 'is', 5, 10);


// muestra sólo 1, debido a que no cuenta subcadenas traslapadas.
$text2 = 'gcdgcdgcd';
echo substr_count($text2, 'gcdgcd');
?>

Ver también

count_chars() - Devuelve información sobre los caracteres usados en una cadena
strpos() - Encuentra la posición de la primera ocurrencia de un substring en un string
substr() - Devuelve parte de una cadena
strstr() - Encuentra la primera aparición de un string

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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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