count_chars
(PHP 4, PHP 5)
count_chars 
Return information about characters used in a string
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 defaults 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.
Example 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"; } ?>

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() and
substr_count().