  lua-l archive

• Subject: Re: Hex numbers
• From: "Mauro Vezzosi"<mvezzosi@...>
• Date: Tue, 29 Aug 2000 14:55:03 +0200

```If someone is interested in, this is my luaO_str2d() in lobject.c for
Lua 4.0a (I guess that Erik's source works in Lua 3.2).
You can use bases from 1 (!) to 26, + and - sign, lower or upper case
(IE 0x or 0X). You can't use base 24 because I use 0X like 0P for
hexadecimal numbers. I also changed luaX_lex() in llex.c to accept this
kind of numbers (but it need to be improved).

Mauro

int luaO_str2d (const char *s, Number *result) {  /* LUA_NUMBER */
double a = 0.0;
int point = 0;  /* number of decimal digits */
int sig;
while (isspace((unsigned char)*s)) s++;
sig = 0;
switch (*s) {
case '-': sig = 1;  /* go through */
case '+': s++;
}
if (! (isdigit((unsigned char)*s) ||
(*s == '.' && isdigit((unsigned char)*(s+1)))))
return 0;  /* not (at least one digit before or after the point) */
/* Start of my extension */
if (((unsigned char)*s == '0') && isalpha((unsigned char)*(s + 1))) {
char base, *s2;

base = toupper((unsigned char)*(s + 1));
a = strtoul(s + 2, &s2, (base == 'X') ? 16 : (base - 'A' + 1));
if (*s2 != '\0' || s + 2 == s2) return 0;  /* invalid trailing
characters? */
*result = sig ? -a : a;
return 1;
}
/* End of my extension */
while (isdigit((unsigned char)*s))
a = 10.0*a + (*(s++)-'0');
if (*s == '.') {
s++;
while (isdigit((unsigned char)*s)) {
a = 10.0*a + (*(s++)-'0');
point++;
}
}
if (sig) a = -a;
if (*s == 'e' || *s == 'E') {
int e = 0;
s++;
sig = 0;
switch (*s) {
case '-': sig = 1;  /* go through */
case '+': s++;
}
if (!isdigit((unsigned char)*s)) return 0;  /* no digit in the
exponent? */
do {
e = 10*e + (*(s++)-'0');
} while (isdigit((unsigned char)*s));
if (sig) e = -e;
point -= e;
}
while (isspace((unsigned char)*s)) s++;
if (*s != '\0') return 0;  /* invalid trailing characters? */
if (point != 0) {
if (point > 0) a /= expten(point);
else           a *= expten(-point);
}
*result = a;
return 1;
}

```