count_chars

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

count_charsReturn information about characters used in a string

Опис

count_chars(string $string, int $mode = 0): array|string

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

Параметри

string

The examined string.

mode

See return values.

Значення, що повертаються

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.

Журнал змін

Версія Опис
8.0.0 Prior to this version, the function returned false on failure.

Приклади

Приклад #1 count_chars() example

<?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";
}
?>

Поданий вище приклад виведе:

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.

Прогляньте також

  • strpos() - Знаходить позицію першого входження підрядка в рядку
  • substr_count() - Count the number of substring occurrences

add a note

User Contributed Notes 8 notes

up
24
marcus33cz
12 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
2
Eric Pecoraro
19 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
seb at synchrocide dot net
20 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
0
Anonymous
8 years ago
count_chars for multibyte supported.

<?php

function 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;

}
?>
up
-1
Andrey G
4 years ago
Checking that two strings are anagram:

<?php

function isAnagram($string1, $string2)
{
return
count_chars($string1, 1) === count_chars($string2, 1);
}

isAnagram('act', 'cat'); // true

?>
up
-1
pzb at novell dot com
17 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
-3
phpC2007
16 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
-5
mlong at mlong dot org
22 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")];
?>
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