gaynor@topaz.UUCP (04/24/87)
I thought I'd write this thing myself, and pass it around. Please
find enclosed the source for a function that returns the long int
equivalent of the string specifying a number in a given radix, from 2
to Z. Enjoy! (Note snips at BOTTOM as well as TOP.)
Silver.
O o
=============== snip ============ X ============= snip ================
/ \
/**********************************************************************\
* Written by: Andrew Gaynor (gaynor@topaz.rutgers.edu) *
* *
* License (Sure it's informal, vague, and has lots of loopholes, but *
* the meaning is clear. I don't even know if it's binding, *
* but I give the code in good faith, so accept it likewise.) *
* *
* Hi! About this code, here... It's as good as yours, and you may do *
* what you wish with it, as long as you play by these rules: *
* (1) Everything that's here now must remain here. You can COMMENT *
* things out, fine, but don't SNIP them out. *
* (2) All modifications are to be commented as being done by the *
* modifier. That is, if you make a change, put YOUR name on it. *
* For example, look at how I forgot and added negative numbers. *
* (3) I disclaim all responsibility for the consequences of any use *
* of this code. If you use it, I'm not to blame for anything *
* that happens. *
\**********************************************************************/
/* I just hate not seeing it there :-) */
#define then
/**********************************************************************\
* num_in_rad takes a string of an integer in a given radix, in the *
* form "<num_in_rad>#<rad>", and returns the equivalent (long) integer *
* in decimal. Possible radixes are 2, 3, ..., 9, A, B, ..., Z. *
* Possible digits in a radix r are 0, 1, ..., predecessor (r). This *
* thing does no error checking. I almost forgot: the #<rad> part may *
* be ommitted, and the radix defaults to 10 (10 == A). *
\**********************************************************************/
/**************** gaynor@topaz.rutgers.edu: ADDITION 1 ****************\
* I forgot to handle negative numbers! They have been added, so the *
* first thing in <num_in_rad> above may be a minus sign. *
\**********************************************************************/
long int num_in_rad (num_with_rad_str)
char *num_with_rad_str;
{
/* num_str is the string of the number in radix, the first piece */
/* of num_with_rad_str - point num_str where num_with_rad_str */
/* points - it's really the same thing, once that pesky '#' is */
/* replaced with '\0' (if there at all) */
char *num_str = num_with_rad_str;
int rad_int = 0; /* the radix as an integer */
int num_int = 0; /* the number as an integer */
/* 1 */ int sign = 1;
/* 1 */ /* if the number is negative, ... */
/* 1 */ if (*num_with_rad_str == '-')
/* 1 */ then
/* 1 */ {
/* 1 */ /* record the fact and skip the sign */
/* 1 */ sign = -1;
/* 1 */ ++num_str;
/* 1 */ ++num_with_rad_str;
/* 1 */ };
/* while num_with_rad_str doesn't point */
/* at '#' or '\0', increment it */
while (*num_with_rad_str != '#' && *num_with_rad_str)
++num_with_rad_str;
/* if num_with_rad_str points at '#' (ie not '\0') ... */
if (*num_with_rad_str)
then /* '#' */
{
/* set the terminator for num_str by replacing the '#' with */
/* '\0' - increment num_with_rad_str to point at the radix */
*(num_with_rad_str++) = '\0';
/* if it points to a digit (decimal), set rad_int to the */
/* conversion of that digit (in radix) to an integer */
/* (decimal) - otherwise, it must be letter-digit, so */
/* convert that letter to the proper integer (decimal) */
/* (ie A = 10, B = 11, ...) */
rad_int = (int) ((*num_with_rad_str <= '9') ?
(*num_with_rad_str - '0') :
(*num_with_rad_str - 'A' + 10));
/* convert num_str to an integer (decimal) - for each digit, */
/* increase the power by multiplying by the radix and add */
/* the digit. */
/* while num_str points at a digit (in radix) ... */
while (*num_str)
/* num_int = rad_int * num_int (increase power) */
/* + the conversion of the next digit (in */
/* radix) to an integer (decimal) (as */
/* before) */
num_int = rad_int * num_int
+ (int) ((*num_str <= '9') ?
(*(num_str++) - '0') :
(*(num_str++) - 'A' + (char) 10));
/* restore '#' that was replaced before (with '\0', */
/* remember?), to act as a terminator for num_str. */
*num_str = '#';
}
else /* '\0' */
/* it's assumed to be decimal if no radix supplied */
while (*num_str)
num_int = 10 * num_int
+ (int) (*(num_str++) - '0');
/* 1 */ /* The sign, below... */
return (sign * num_int);
}
O o
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/ \
Silver.
/-------------------------------------------------\
| uucp: ...!topaz!gaynor ...!topaz!remus!gaynor |
| ~~~~~~~~~~~~~~~~ |
| arpa: gaynor@topaz silver@aim |
\-------------------------------------------------/