count_chars

(PHP 4, PHP 5)

count_chars — 文字列で使用されている文字に関する情報を返す

説明

mixed count_chars ( string $string [, int $mode ] )

string において各バイト値 (0..255) が存在する数をかぞえ、様々な手法で返します。

パラメータ

string: 調べたい文字列。
mode: オプションのパラメータ mode のデフォルトは 0 です。

返り値

mode の値により、 count_chars() は以下の値のどれかを返します。

0 - 各バイト値をキー、各バイトの出現回数を値とする配列。
1 - 0と同じですが、各バイト値の出現回数がゼロより大きいものの一覧となります。
2 - 0と同じですが、各バイト値の出現回数がゼロであるものの一覧となります。
3 - すべての一意な文字を含む文字列を返します。
4 - 使用されていない全ての文字を含む文字列を返します。

例

例1 count_chars() の例


<?php
$data = "Two Ts and one F.";

foreach (count_chars($data, 1) as $i => $val) {
   echo "There were $val instance(s) of \"" , chr($i) , "\" in the string.\n";
}
?>

上の例の出力は以下となります。

There were 4 instance(s) of " " in the string.
There were 1 instance(s) of "." in the string.
There were 1 instance(s) of "F" in the string.
There were 2 instance(s) of "T" in the string.
There were 1 instance(s) of "a" in the string.
There were 1 instance(s) of "d" in the string.
There were 1 instance(s) of "e" in the string.
There were 2 instance(s) of "n" in the string.
There were 2 instance(s) of "o" in the string.
There were 1 instance(s) of "s" in the string.
There were 1 instance(s) of "w" in the string.

参考

crc32

convert_uuencode

Last updated: Fri, 10 Oct 2008

add a note User Contributed Notes
count_chars

phpC2007
05-Dec-2007 12:42


Here's a function to count number of strings in a string. It can be used as a simple utf8-enabled count_chars (but limited to a single mode)...



<?php

function utf8_count_strings($stringChar)

{

    $num = -1;

    $lenStringChar = strlen($stringChar);

    

    for ($lastPosition = 0; 

        $lastPosition !== false;

        $lastPosition = strpos($textSnippet, $stringChar, $lastPosition + $lenStringChar))

    {

        $num++;

    }

    

    return $num;

}

?>

pzb at novell dot com
29-Jul-2007 10:29


This function is great for input validation.  I frequently need to check that all characters in a string are 7-bit ASCII (and not null).  This is the fastest function I have found yet:



<?php

function is7bit($string) {

    // empty strings are 7-bit clean

    if (!strlen($string)) {

        return true;

    }

    // count_chars returns the characters in ascending octet order

    $str = count_chars($str, 3);

    // Check for null character

    if (!ord($str[0])) {

        return false;

    }

    // Check for 8-bit character

    if (ord($str[strlen($str)-1]) & 128) {

        return false;

    }

    return true;

}

?>

Patrick Palka
11-Apr-2007 12:46


A faster unique character-checking function:



<?php

function chr_unique($string) {

  return strlen(count_chars($string, 3));

}

?>

apinpratap at gmail dot com
30-Mar-2007 03:54


this code can find each characters count



<?php

$enter = 0;

$data = strtolower ($inputString);

foreach (count_chars ($data, 1) as $i => $val) 

    {

        if ($enter == 1)

        {

            $enter = 0;

            continue;

        }

        if (chr ($i) == "\n")

        {

            echo "There are $val instance(s) of \" Enter \" in the string.\n";

            $enter = 1;

        }

        else

        {

            echo "There are $val instance(s) of \"" , chr ($i) , "\" in the string.\n";

        }

    }

?>

Eric Pecoraro
27-May-2005 11:31


<?php



// Require (n) unique characters in a string

// Modification of a function below which ads some flexibility in how many unique characters are required in a given string.



$pass = '123456' ; // true

$pass = '111222' ; // false



req_unique($pass,3);



function req_unique($string,$unique=3) {

    if ( count(count_chars($string,1)) < $unique) {

        echo 'false';

    }else{

        echo 'true';

    }

}



?>

Alex Gemmell
15-Feb-2005 03:03


Use: Great for checking for unique characters in a password.



I wanted to check that my website users, when registering a user account, chose a "valid" (not-so-easily-guessed) password.



One of the many checks was that the password must have 6 unique characters.  I was tying myself in knots with all kinds of recursive array calling when I was offered this wonderful one line solution:



function check_password($password) {



   #Have 6 unique characters

   if (count(count_chars($password, 1)) < 6) return false;



   #

   # other checks returning false as necessary

   #

   #



   return true;

}



I cannot claim this wonderful line for myself - a Mr Lynch suggested this to me.  Thanks!

seb at synchrocide dot net
17-May-2004 07:08


After much trial and error trying to create a function that finds the number of unique characters in a string I same across count_chars() - my 20+ lines of useless code were wiped for this:



<?

function unichar($string) {

$two= strtolower(str_replace(' ', '', $string));

$res = count(count_chars($two, 1));

return $res;

}



/* examples :: */



echo unichar("bob"); // 2

echo unichar("Invisibility"); //8

echo unichar("The quick brown fox slyly jumped over the lazy dog"); //26



?>



I have no idea where this could be used, but it's quite fun

mlong at mlong dot org
30-Jan-2002 09:27


// Usefulness of the two functions





<?php


 $string="aaabbc";





 // You just want to count the letter a


 $acount=substr_count($string,"a");





 // You want to count both letter a and letter b


 $counts=count_chars($string,0);


 $acount=$counts[ord("a")];


 $bcount=$counts[ord("b")];


?>

maotin at hongkong dot com
01-Feb-2001 10:04


Here are some more experiments on this relatively new and extremely handy function.





<?php


$string = 'I have never seen ANYTHING like that before! My number is "4670-9394".';





foreach(count_chars($string, 1) as $chr => $hit)


echo 'The character '.chr(34).chr($chr).chr(34).' has appeared in this string '.$hit.' times.<BR>';





#The result looks like


#The character " " has appeared in this string 11 times.





echo count_chars($string,3);


#The output is '!"-.034679AGHIMNTYabefhiklmnorstuvy'





echo strlen($string).' is not the same as '.strlen(count_chars($string, 3));





#This shows that '70 is not the same as 36'


?>





As we can see above:





1)If you cares only about what is in the string, use count_chars($string, 1) and it will return an (associative?) array of what shows up only.





2) Either I misunderstood what the manul actually said, or it does not work the way it described: count_chars($strting, 3) actually returned a string of what characters are in the string, not a string of their byte-values (which is great because a string of numbers would be much harder to handle);





3)This is a short version of password checking: get the original string's length, then compare with the length of the string returned by count_chars($string,3).  





<?php


$length_of_string = strlen($string);


$num_of_chars = strlen(count_chars($string, 3));





$diff = ($length_of_string - $num_of_chars);





if ($diff)


echo 'At least one character has been used more than once.';


else


echo 'All character have been used only once.;


?>





Note that since $num_of_chars gives no information about the actual number of occurance, we cannot go any further by the same rationale and say when $diff =2 then 2 characters showed up twice; it might be 1 character showd up 3 times, we have no way to tell (a good tolerance level setter, though).  You have to get the array and check the values if you want to have more control.





4) Final trick: now we have a primitive way to count the number of words in a string! (or do we have a fuction for that already?)

add a note

crc32

convert_uuencode

Last updated: Fri, 10 Oct 2008