XML escape characters Migrating from C/C++ to PHP - function to determine character type

In C/C++, the header file ctype.h defines a set of macros about character types, which can get the type of a given character.
There are no related functions in PHP. A few days ago, I found that the PHP downloaded from www.mm4.de provides an extension library named php_ctype.dll.
After loading, I found that some such functions are provided, and I have compiled them for your reference.
After loading the php_ctype.dll file correctly in PHP, use <?php phpinfo();?> to see the following information:
. The usage of all functions is basically the same as in C/C++. The difference is that in C/C++, the function parameters are chars, while in PHP, the function parameters can be strings. For example:
<?php
$string="123ADAADAD";
if(isalnum($string))
{
echo "Only uppercase and lowercase letters and numbers!";
}
?>
Attachment: php_ctype.dll Supported functions
bool isalnum(string)
bool isalpha(string)
bool iscntrl(string)
bool isdigit(string)
bool isgraph(string)
bool islower(string)
bool isprint(string)
bool ispunct(string )
bool isspace(string)
bool isupper(string)
bool isxdigit(string)
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The above introduces the XML escape character migration from C/C++ to PHP - the function to determine the character type, including the content of XML escape characters. I hope it will be helpful to friends who are interested in PHP tutorials.