Description
mixed 
count_chars ( string string [, int mode])
     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.
       
    
     
例子 1. count_chars() example 
<?php
  $data = "Two Ts and one F.";
  $result = count_chars($data, 0);
  for ($i=0; $i < count($result); $i++) {    if ($result[$i] != 0)        echo "There were $result[$i] instance(s) of \"" , chr($i) , "\" in the string.\n"; }
  ?>
 |  
 
       This 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().