Programming PHP, 3rd Edition

Name

count_chars

Synopsis

mixed count_chars(string string[, int mode])

Returns the number of occurrences of each byte value from 0–255 in string; mode determines the form of the result. The possible values of mode are:

0 (default)	Returns an associative array with each byte value as a key and the frequency of that byte value as the value
1	Same as above, except that only byte values with a nonzero frequency are listed
2	Same as above, except that only byte values with a frequency of zero are listed
3	Returns a string containing all byte values with a nonzero frequency
4	Returns a string containing all byte values with a frequency of zero