ctype_xdigit()

ctype_xdigit() — Check for character(s) representing a hexadecimal digit.

ctype_xdigit() — Checks if all of the characters in the provided string, text, are hexadecimal ‘digits’.

Inputs: text: The tested string. If an int between -128 and 255 inclusive is provided, it is interpreted as the ASCII value of a single character (negative values have 256 added in order to allow characters in the Extended ASCII range). Any other integer is interpreted as a string containing the decimal digits of the integer.

Returns: 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. When called with an empty string the result will always be false.