The character type functions are Boolean functions used to check the type of the characters on a string. They return true if all the characters are ofthe type specified by the function. These functions are useful for example if you want to validate a new password submitted by a user. You can check with them that the password submitted do not contains any special character.

The following example shows the use of these functions

 

<?php $para="There are 10 players on each team."; print ctype_alnum($para)."<br>"; //returns 1 (true) print ctype_alpha($para)."<br>"; //returns 0 (false) $myhex="AF12" print ctype_xdigit($myhex)."<br>"; //returns 1 (true) ?>

The table bellow list these functions:

Function
Type of characters checked
Example
ctype_alnum 
alphanumeric 
0-9 A-Z a-z
ctype_alpha
alphabetic 
A-Z a-z
ctype_cntrl 
control
Tab, esc, etc
ctype_digit 
numeric
0-9
ctype_graph 
any printable character except space
0-9 A-Z a-z
ctype_lower 
lowercase
a-z
ctype_print 
printable
0-9 A-Z a-z space
ctype_punct 
any printable character which is not whitespace or an alphanumeric character 
Nn 0-9 A-Z a-z space
ctype_space 
whitespace
blank character , tab, vertical tab, etc.
ctype_upper 
uppercase 
A-Z
ctype_xdigit 
representing a hexadecimal digit 
Decimal digits and characters frm A-F and a-f