**Syntax:**mixed count_chars ( string $string [, int $mode = 0 ] )
**Description:**count_chars — Return information about characters used in a string.Counts the number of occurrences of every byte-value (0..255) in string and returns it in various ways.
**Return Values:**
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.

### Example 1

<?php $data = "Three TTs and one F."; foreach (count_chars($data, 1) as $i => $val) { echo "There were $val instance(s) of \"" , chr($i) , "\" in the string.\n<br/>"; } ?>

**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 3 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 3 instance(s) of "e" in the string. There were 1 instance(s) of "h" in the string. There were 2 instance(s) of "n" in the string. There were 1 instance(s) of "o" in the string. There were 1 instance(s) of "r" in the string. There were 1 instance(s) of "s" in the string.