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Use isdigit(3) instead of a reimplementation of it

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C89 defined isdigit as a function that tests for any decimal-digit
character, defining the decimal digits as 0 1 2 3 4 5 6 7 8 9.

I don't own a copy of C89 to check, but check in C17:

7.4.1.5
5.2.1

More specifically:

> In both the source and execution basic character sets, the value
> of each character after 0 in the above list of decimal digits
> shall be one greater than the value of the previous.

And since in ascii(7), the character after '9' is ':', it's highly
unlikely that any implementation will ever accept any
_decimal digit_ other than 0..9.

POSIX simply defers to the ISO C standard.

This is exactly what we wanted from ISDIGIT(c), so just use it.
Non-standard implementations might have been slower or considered
other characters as digits in the past, but let's assume
implementations available today conform to ISO C89.

Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
This commit is contained in:
Alejandro Colomar 2021-12-28 19:55:09 +01:00
parent 44126d85ee
commit 8f134c0bea
1 changed files with 3 additions and 12 deletions
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15
libmisc/getdate.y
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@ -31,15 +31,6 @@
#include <ctype.h> #include <ctype.h>
#include <time.h> #include <time.h>
/* ISDIGIT differs from isdigit(3), as follows:
- Its arg may be any int or unsigned int; it need not be an unsigned char.
- It's typically faster.
Posix 1003.2-1992 section 2.5.2.1 page 50 lines 1556-1558 says that
only '0' through '9' are digits. Prefer ISDIGIT to isdigit(3) unless
it's important to use the locale's definition of `digit' even when the
host does not conform to Posix. */
#define ISDIGIT(c) ((unsigned) (c) - '0' <= 9)
#include "getdate.h" #include "getdate.h"
#include <string.h> #include <string.h>
@ -760,18 +751,18 @@ yylex (void)
while (isspace (*yyInput)) while (isspace (*yyInput))
yyInput++; yyInput++;
if (ISDIGIT (c = *yyInput) || c == '-' || c == '+') if (isdigit (c = *yyInput) || c == '-' || c == '+')
{ {
if (c == '-' || c == '+') if (c == '-' || c == '+')
{ {
sign = c == '-' ? -1 : 1; sign = c == '-' ? -1 : 1;
if (!ISDIGIT (*++yyInput)) if (!isdigit (*++yyInput))
/* skip the '-' sign */ /* skip the '-' sign */
continue; continue;
} }
else else
sign = 0; sign = 0;
for (yylval.Number = 0; ISDIGIT (c = *yyInput++);) for (yylval.Number = 0; isdigit (c = *yyInput++);)
yylval.Number = 10 * yylval.Number + c - '0'; yylval.Number = 10 * yylval.Number + c - '0';
yyInput--; yyInput--;
if (sign < 0) if (sign < 0)