Description
mixed
count_chars ( string string [, int mode])
Counts the number of occurrences of every bytevalue (0..255) in
string and returns it in various ways.
The optional parameter mode default to
0. Depending on mode
count_chars() returns one of the following:
0  an array with the bytevalue as key and the frequency of
every byte as value.
1  same as 0 but only bytevalues with a frequency greater
than zero are listed.
2  same as 0 but only bytevalues with a frequency equal to
zero are listed.
3  a string containing all used bytevalues is returned.
4  a string containing all not used bytevalues is returned.
例子 1. count_chars() example
<?php
$data = "Two Ts and one F.";
$result = count_chars($data, 0);
for ($i=0; $i < count($result); $i++) { if ($result[$i] != 0) echo "There were $result[$i] instance(s) of \"" , chr($i) , "\" in the string.\n"; }
?>

This 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() and
substr_count().