These two functions perform integer to character conversion and vice-versa using the internal code of the machine. Although most computers now use the ASCII character code, it is by no means universal, so these functions can only be used in a very limited way in portable software.
CHAR(I) returns the character at position I in the code table. For example, on a machine using ASCII code, CHAR(74) = 'J', since "J" is the character number 74 in the ASCII code table.
ICHAR(STRING) returns the integer position in the code table of
the first character of the argument STRING. For example, on a
machine using ASCII code,