php man page for ctype_xdigit

CTYPE_XDIGIT(3) 							 1							   CTYPE_XDIGIT(3)

ctype_xdigit - Check for character(s) representing a hexadecimal digit

SYNOPSIS
       bool ctype_xdigit (string  $text)

DESCRIPTION
	Checks if all of the characters in the provided string, $text, are hexadecimal 'digits'.

PARAMETERS
	      o $text
		- The tested string.

RETURN VALUES
	Returns TRUE if every character in $text is a hexadecimal 'digit', that is a decimal digit or a character from [A-Fa-f] , FALSE otherwise.

EXAMPLES
       Example #1

	      A ctype_xdigit(3) example

	      <?php
	      $strings = array('AB10BC99', 'AR1012', 'ab12bc99');
	      foreach ($strings as $testcase) {
		  if (ctype_xdigit($testcase)) {
		      echo "The string $testcase consists of all hexadecimal digits.
";
		  } else {
		      echo "The string $testcase does not consist of all hexadecimal digits.
";
		  }
	      }
	      ?>

	      The above example will output:

	      The string AB10BC99 consists of all hexadecimal digits.
	      The string AR1012 does not consist of all hexadecimal digits.
	      The string ab12bc99 consists of all hexadecimal digits.

NOTES
       Note

	       If an integer between -128 and 255 inclusive is provided, it is interpreted as the ASCII value of a single character (negative val-
	      ues have 256 added in order to allow characters in the Extended ASCII range). Any other integer is interpreted as a string  contain-
	      ing the decimal digits of the integer.

SEE ALSO
       ctype_digit(3).

PHP Documentation Group 													   CTYPE_XDIGIT(3)