strcspn

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

strcspn — Trova la lunghezza del segmento iniziale che non soddisfa una maschera

Descrizione

strcspn(
    string $str1,
    string $str2,
    int $inizio = ?,
    int $lunghezza = ?
): int

Restituisce la lunghezza del segmento iniziale di str1 che non contiene nessuno dei caratteri specificati in str2.

Dal PHP 4.3.0, strcspn() accetta due parametri interi, opzionali, che possono essere utilizzati per definire la posizione di inizio e la lunghezza della stringa da esaminare.

Nota: Questa funzione è binary-safe (gestisce correttamente i file binari)

Vedere anche strspn().

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User Contributed Notes 5 notes

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AT-HE (at_he AT hotmai1 DOT com) ¶

18 years ago

this function can be used like strspn(), except while that can be used to compare a string with an allowed pattern, this one can be use to compare a string with a FORBIDDEN pattern

so, to know if any forbidden character has a position inside our string, we can use (not tested with backslashes)...

<?php
// LARGE VERSION
$forbidden="\"\\?*:/@|<>";
if (strlen($filename) != strcspn($filename,$forbidden)) {
    echo "you cant create a file with that name!";
}

// SHORT VERSION
if (strlen($filename) - strcspn($filename,"\"\\?*:/@|<>")) {
    echo "i told you, you cant create that file";
}
?>

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maskedcoder at hotmail dot com ¶

19 years ago

useful for finding beginning of quotes and/or tags in a variable containing html.  
    $pos = strcspn($data, '<"\''); 
will find the first occurance of either the beginning of a tag, or a double- or single-quoted string.

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legacyprog at routinz dot net ¶

13 years ago

When you use the third parameter remember that the function will return the number of characters it bypassed, which will *not* be the position in your source string.  It's a simple fix to just add your third parameter value to the function result to get the position in the first string where the scan stopped, but I didn't think of it at first.

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Anonymous ¶

15 years ago

strcspn() can also be thought of as analogous to the following regular expression:
<?php
// where ... represents the mask of characters
preg_match('/[^ ...]/', substr($subject, $start, $length) );
?>
By this analogy, strcspn() can be used in place of some regular expressions to match a pattern without the overhead of a regex engine -- for example, ways to verify if an input string represents a binary value:
<?php
preg_match('/^[01]+$/i', $subject);
// or...
!preg_match('/[^01]/i', $subject);

// ...or using strcspn()
!strcspn($subject, '01');
?>

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nospam at nospam dot com ¶

8 years ago

It might not be clear from the example, that

strcspn('abcdhelloabcd', 'abcd', -9, -5) == 4

because it's only evaluating 'hell' which doesn't contain any mask, so returns strlen('hell').

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