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OS/2 Shareware BBS: 10 Tools
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numio.doc
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1996-06-20
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Summary of routines in numio.i:
(3000) .1 <- character from input
(3001) Prints .2 as a character
(3080) .1 <- a 16-bit number from the user
(3089) .1 <- a 16-bit number from the user, with an error message if
non-digits are encountered
(3090) Displays the value in .1
(3099) Displays the value in .1 and prints a newline
(3080) :1 <- a 32-bit number from the user
(3089) :1 <- a 32-bit number from the user, with an error message if
non-digits are encountered
(3090) Displays the value in :1
(3099) Displays the value in :1 and prints a newline
(3990) Initializes internal arrays.
The file numio.i contains routines for doing "wimpmode"-style I/O - or
in other words, the C-INTERCAL equivalent of atoi and itoa. (3080) and
(3090) translate the ASCII input as a number (yes, a number as in
[0-9]*), and (3090) and (3190) do the same for displaying numbers in
ASCII. (By the way, the routines can also be made to support EBCDIC:
simply replace #3 with #15 on lines 41, 81, and 107.)
Each routine also has a "niner" variation. For itoa, (3099) and (3190)
print a newline at the end of the number. In the case of atoi, (3089)
and (3189) make sure that the number ends with a newline. In other
words, they ensure there are no other non-numeric characters in the
input line. If there are, a typically snide INTERCAL error message is
displayed. (The regular versions work like C's atoi in that they
return as soon as they see any non-digit.)
There's not too much to note about these routines. The atoi versions
use the shift-and-add trick to avoid multiplying by 10, so they should
be pretty efficient (snort). itoa has no such shortcuts, and the
routines use the modified division routine which also returns the
remainder. The 16-bit version is at (2030), and is the familiar one
created by Louis Howell, copied from syslib2.i. The 32-bit version is
at (2530), and is just a copy of the standard library routine without
the lines that throw away the remainder at the end.
The library reserves the use of two arrays - ,3000 and ,3001 - for
input and output respectively. Each array has one dimension of one
element, and they are used to provide a getchar and putchar: routines
(3000) and (3001).
The arrays are initialized by routine (3990); this should be called
before using any other routines in this file.
Note also that for these routines to work properly, they must be used
more or less exclusively in regards to other array I/O. Otherwise, the
getchar and putchar subroutines will get out of synch with the
Turing-text character loop. If you do want to do other I/O while using
these routines, you can use (3000) and (3001) as a getchar and putchar
(note that the latter expects that the character values have already
been reversed). Or, you can simply re-initialize the ,3000 and/or
,3001 values after you are done, by storing in them the ASCII value of
the last character that you wrote in and/or read out. For example,
if you have displayed some strings and the last thing to be printed
was a newline, then:
DO ,3001SUB#1 <- #80
would allow you to safely call the itoa routines, since 80 is the
bit-reversal of 10.
It is my earnest hope that C-INTERCAL programmers everywhere will
flock to these handy routines, and C-INTERCAL users will thus no
longer need to fear that they might succumb to the foul and awful
temptation to use the dastardly +wimpmode option.