In mathematics and computing, the hexadecimal (also base 16 or hex) numeral system is a positional numeral system that represents numbers using a radix (base) of 16. Unlike the common way of representing numbers using 10 symbols, hexadecimal uses 16 distinct symbols, most often the symbols "0"–"9" to represent values 0 to 9, and "A"–"F" (or alternatively "a"–"f") to represent values 10 ... It is a convention in C to identify the end of a character string with a null (zero) character. Therefore, C compilers automatically suffix character strings with such a terminator. Thus, the string "Jon" sets up an array of four characters ('J', 'o', 'n', and zero) and generates the address of the first character, for use by the program.