A char containing a character. If the character pointed to by index is a "%" and there are at least two characters following the "%", and the two characters are valid hexadecimal digits, the hexadecimal digits are converted to char. Otherwise, the character at index is returned. Valid hexadecimal digits are: 0-9, a-f, A-F.
On return, the value of index contains the index of the character following the one returned.
Type Reason ArgumentOutOfRangeException index < 0, or index >= the number of characters in pattern.