The count_chars() function returns information about characters used in a string (for example, how many times an ASCII character occurs in a string, or which characters that have been used or not been used in a string).
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.
| Parameter | Description |
|---|---|
| string | The examined string. |
| moder | See 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.