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strlen

(PHP 3, PHP 4, PHP 5)

strlen -- Get string length

Description

int strlen ( string string )

Returns the length of the given string.

Przykład 1. A strlen() example


<?php

$str = 'abcdef';

echo strlen($str); // 6



$str = ' ab cd ';

echo strlen($str); // 7

?>

See also count(), and mb_strlen().

User Contributed Notes

Hage Yaapa
12-Jan-2006 12:51


Sometimes you really wanna make sure no user edits the 'maxlength' attribute of the HTML page and POSTs a 5 Mb string to your script. Probably, advanced programmers already take precautions, this one is just a very simple tip for beginners on how to check the character lenth of the POST variables in an effective manner.



<?php



// ALWAYS clean the POST variables of any HTML tags first.

// And here we do it in one easy step.

 $_POST = array_map('strip_tags', $_POST);

 

// These are the POST variables in the example

 $alias = $_POST['alias'];

 $name = $_POST['name'];

 $status = $_POST['status'];

 $year = $_POST['year'];

 

// We create an array that contains the expected character length

// for each POST variable

 $exlen = array (

      'alias'=>12,

      'name'=>30,

      'status'=>10,

      'year'=>4

);

 

// Now check if any of them exceeds the expected length

 foreach ($exlen as $key=>$val) {

      if (strlen($$key) > $val) {

            // The user has definitely edited the HTML! He has a lot of time, could be bad.

          // This section can edited according to your needs - very simple to complex.

          // Log the event or send an e-mail to the admin at the basic.

          // However, in this example we just print a warning.    

          print 'WARNING: The FBI is looking for you, dude!';

          exit;

          // The best part is that the script won't look for any other 

          // POST variables other than the ones which we are expecting already.

      }

}

?>



Similarly, with the use of Regular Expressions you could check the data type and string format too.

anpaza at mail dot ru
30-Nov-2005 09:58


Here's a better strlen() for UTF-8 strings that doesn't access the byte past end of the string (on which newer PHP barfs):



function strlen_utf8 ($str)

{

    $i = 0;

    $count = 0;

    $len = strlen ($str);

    while ($i < $len)

    {

    $chr = ord ($str[$i]);

    $count++;

    $i++;

    if ($i >= $len)

        break;



    if ($chr & 0x80)

    {

        $chr <<= 1;

        while ($chr & 0x80)

        {

        $i++;

        $chr <<= 1;

        }

    }

    }

    return $count;

}

ralf at bruderherz dot com
17-Nov-2005 12:31


Why not:



function b_strlen($str){

        $ret = 0;

        for($i = 0; $i < strlen($str); $i++){

            if( (ord($str{$i}) >= 0 && ord($str{$i}) <= 127) || ord($str{$i}) >= 192 ) $ret++;

        }

        return $ret;

}



It's easier I think...

Fabi K
30-Oct-2005 12:08


So here a short script that will count the letters in an utf8-string. This will work for the whole utf-8 character set.



function strlen_utf8(&$str) {

    while($str[$i]) {

        $cnt = $cnt = countLeadingBits(ord($str[$i]));

        $i += $cnt>0 ? $cnt : 1;    // skip following bytes if the char was bigger than a Byte.

        $diff += $cnt>0 ? $cnt-1 : 0;    // counting every skipped Byte.

    }

    return ($i - $diff);

}



define(FIRST_BIT, 0x80);

/**

    This function counts the leading 'on'-Bits in a Byte.

    @param char The byte to analyse. Must be a number. Use ord() to analyse characters.

    @return The number of leading bits that where set (1).

*/

function countLeadingBits($char) {

    $char = $char & 255;                    // deleting 'on'-bits that where greater than 2^8 => every number is less or equal 0xff(255)

    //echo sprintf("%08d ", decbin($char));

    if( (FIRST_BIT & $char) === FIRST_BIT) {    // a leading Bit is found

        return countLeadingBits($char << 1) + 1;

    }

    return 0;

}



$testdata = "abcABC123