count_chars

If you have problems using count_chars with a multibyte string, you can change the page encoding. Alternatively, you can also use this mb_count_chars version of the function. Basically it is mode "1" of the original function.<?php/** * Counts character occurences in a multibyte string * @param string $input UTF-8 data * @return array associative array of characters. */function mb_count_chars($input) {    $l = mb_strlen($input, 'UTF-8');    $unique = array();    for($i = 0; $i < $l; $i++) {        $char = mb_substr($input, $i, 1, 'UTF-8');        if(!array_key_exists($char, $unique))            $unique[$char] = 0;        $unique[$char]++;    }    return $unique;}$input = "Let's try some Greek letters: αααααΕεΙιΜμΨψ, Russian: ЙЙЫЫЩН, Czech: ěščřžýáíé";print_r( mb_count_chars($input) ); //returns: Array ( [L] => 1 [e] => 7 [t] => 4 ['] => 1 [s] => 5 [ ] => 9 [r] => 3 [y] => 1 [o] => 1 [m] => 1 [G] => 1 [k] => 1 [l] => 1 [:] => 3 [α] => 5 [Ε] => 1 [ε] => 1 [Ι] => 1 [ι] => 1 [Μ] => 1 [μ] => 1 [Ψ] => 1 [ψ] => 1 [,] => 2 [R] => 1 [u] => 1 [i] => 1 [a] => 1 [n] => 1 [Й] => 2 [Ы] => 2 [Щ] => 1 [Н] => 1 [C] => 1 [z] => 1 [c] => 1 [h] => 1 [ě] => 1 [š] => 1 [č] => 1 [ř] => 1 [ž] => 1 [ý] => 1 [á] => 1 [í] => 1 [é] => 1 )?>

<?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' ; // falsereq_unique($pass,3);function req_unique($string,$unique=3) {    if ( count(count_chars($string,1)) < $unique) {        echo 'false';    }else{        echo 'true';    }}?>

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"); // 2echo unichar("Invisibility"); //8echo 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

count_chars for multibyte supported.<?phpfunction mb_count_chars ($string, $mode = 0) {        $result =  array_fill(0, 256, 0);        for ($i = 0, $size = mb_strlen($string); $i < $size; $i++) {        $char = mb_substr($string, $i, 1);        if (strlen($char) > 1) {            continue;        }                $code = ord($char);        if ($code >= 0 && $code <= 255) {            $result[$code]++;        }    }        switch ($mode) {        case 1: // same as 0 but only byte-values with a frequency greater than zero are listed.            foreach ($result as $key => $value) {                if ($value == 0) {                    unset($result[$key]);                }            }            break;        case 2: // same as 0 but only byte-values with a frequency equal to zero are listed.            foreach ($result as $key => $value) {                if ($value > 0) {                    unset($result[$key]);                }            }            break;        case 3: // a string containing all unique characters is returned.            $buildString = '';            foreach ($result as $key => $value) {                if ($value > 0) {                    $buildString .= chr($key);                }            }            return $buildString;        case 4: // a string containing all not used characters is returned.            $buildString = '';            foreach ($result as $key => $value) {                if ($value == 0) {                    $buildString .= chr($key);                }            }            return $buildString;    }        // change key names...    foreach ($result as $key => $value) {        $result[chr($key)] = $value;        unset($result[$key]);    }        return $result;    }?>

Checking that two strings are anagram:<?phpfunction isAnagram($string1, $string2){  return count_chars($string1, 1) === count_chars($string2, 1);}isAnagram('act', 'cat'); // true?>

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:<?phpfunction 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;}?>

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)...<?phpfunction utf8_count_strings($stringChar){    $num = -1;    $lenStringChar = strlen($stringChar);        for ($lastPosition = 0;         $lastPosition !== false;        $lastPosition = strpos($textSnippet, $stringChar, $lastPosition + $lenStringChar))    {        $num++;    }        return $num;}?>

// 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")];
?>