You get an overview of how the text interpreter converts its numeric input in Literals in source code. This section describes some related words.
By default, the number base used for integer number conversion is
given by the contents of the variable base. Note that a lot of
confusion can result from unexpected values of base. If you
change base anywhere, make sure to save the old value and
restore it afterwards; better yet, use base-execute, which does
this for you. In general I recommend keeping base decimal, and
using the prefixes described in Literals in source code for the
popular non-decimal bases.
base-execute ( i*x xt u – j*x ) gforth-0.7 “base-execute”
execute xt with the content of BASE being u, and
restoring the original BASE afterwards.
base ( – a-addr ) core “base”
User variable – a-addr is the address of a cell that
stores the number base used by default for number conversion during
input and output. Don’t store to base, use
base-execute instead.
hex ( – ) core-ext “hex”
Set base to &16 (hexadecimal). Don’t use hex,
use base-execute instead.
decimal ( – ) core “decimal”
Set base to &10 (decimal). Don’t use decimal, use
base-execute instead.
dpl ( – a-addr ) gforth-0.2 “Decimal-PLace”
User variable – a-addr is the address of a cell that stores the
position of the decimal point in the most recent numeric conversion.
Initialised to -1. After the conversion of a number containing no
decimal point, dpl is -1. After the conversion of 2. it holds
0. After the conversion of 234123.9 it contains 1, and so forth.
Number conversion has a number of traps for the unwary:
base @ . – the number base is always 10 in the current number
base. Instead, use something like base @ dec.
bin but it does not set the number base!
(see General files).
. of a double-precision number to be the
final character in the string. Gforth allows the . to be
anywhere.
You can read numbers into your programs with the words described in Line input and conversion.