Counts the number of occurrences of every byte-value
(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 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 used byte-values is
returned.
4 - a string containing all not used byte-values is
returned.
See also strpos() and
substr_count().