SunshinePHP Developer Conference 2015

count_chars

(PHP 4, PHP 5)

count_charsReturn information about characters used in a string

Description

mixed count_chars ( string $string [, int $mode = 0 ] )

Counts the number of occurrences of every byte-value (0..255) in string and returns it in various ways.

Parameters

string

The examined string.

mode

See return values.

Return Values

Depending on mode count_chars() returns one of the following:

  • 0 - an array with the byte-value as key and the frequency of every byte as value.
  • 1 - same as 0 but only byte-values with a frequency greater than zero are listed.
  • 2 - same as 0 but only byte-values with a frequency equal to zero are listed.
  • 3 - a string containing all unique characters is returned.
  • 4 - a string containing all not used characters is returned.

Examples

Example #1 count_chars() example

<?php
$data 
"Two Ts and one F.";

foreach (
count_chars($data1) as $i => $val) {
   echo 
"There were $val instance(s) of \"" chr($i) , "\" in the string.\n";
}
?>

The above example will output:

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.

See Also

  • strpos() - Find the position of the first occurrence of a substring in a string
  • substr_count() - Count the number of substring occurrences

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User Contributed Notes 9 notes

up
7
marcus33cz
2 years ago
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 )
?>
up
1
apinpratap at gmail dot com
7 years ago
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";
        }
    }
?>
up
1
pzb at novell dot com
7 years ago
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;
}
?>
up
1
seb at synchrocide dot net
10 years ago
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
up
1
qeremy [atta] gmail [dotta] com
1 year ago
Another approach to counting unicode chars.

<?php
function count_chars_unicode($str, $x = false) {
   
$tmp = preg_split('//u', $str, -1, PREG_SPLIT_NO_EMPTY);
    foreach (
$tmp as $c) {
       
$chr[$c] = isset($chr[$c]) ? $chr[$c] + 1 : 1;
    }
    return
is_bool($x)
        ? (
$x ? $chr : count($chr))
        :
$chr[$x];
}

$str = "şeker şeker yâriiiiiiiiiimmmmm";
print_r(count_chars_unicode($str, 'â'));    // frequency of "â"
print_r(count_chars_unicode($str));         // count of uniq chars
print_r(count_chars_unicode($str, true));   // all chars with own frequency
?>

Outputs;
1
9
Array
(
    [ş] => 2
    [e] => 4
    [k] => 2
    [r] => 3
    [ ] => 2
    [y] => 1
    [â] => 1
    [i] => 10
    [m] => 5
)
up
0
Eric Pecoraro
9 years ago
<?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';
    }
}

?>
up
-1
mlong at mlong dot org
12 years ago
// 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")];
?>
up
-1
phpC2007
6 years ago
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;
}
?>
up
-1
maotin at hongkong dot com
13 years ago
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?)
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