reactos/lib/msvcrt/stdlib/strtod.c

   1 /* Copyright (C) 1996 DJ Delorie, see COPYING.DJ for details */
   2 /* Copyright (C) 1994 DJ Delorie, see COPYING.DJ for details */
   3
   4 #include <msvcrt/stdlib.h>
   5
   6
   7 double
   8 strtod(const char *s, char **sret)
   9 {
  10   long double r;                /* result */
  11   int e;                        /* exponent */
  12   long double d;                /* scale */
  13   int sign;                     /* +- 1.0 */
  14   int esign;
  15   int i;
  16   int flags=0;
  17
  18   r = 0.0;
  19   sign = 1;
  20   e = 0;
  21   esign = 1;
  22
  23   while ((*s == ' ') || (*s == '\t'))
  24     s++;
  25
  26   if (*s == '+')
  27     s++;
  28   else if (*s == '-')
  29   {
  30     sign = -1;
  31     s++;
  32   }
  33
  34   while ((*s >= '0') && (*s <= '9'))
  35   {
  36     flags |= 1;
  37     r *= 10.0;
  38     r += *s - '0';
  39     s++;
  40   }
  41
  42   if (*s == '.')
  43   {
  44     d = 0.1L;
  45     s++;
  46     while ((*s >= '0') && (*s <= '9'))
  47     {
  48       flags |= 2;
  49       r += d * (*s - '0');
  50       s++;
  51       d *= 0.1L;
  52     }
  53   }
  54
  55   if (flags == 0)
  56   {
  57     if (sret)
  58       *sret = (char *)s;
  59     return 0;
  60   }
  61
  62   if ((*s == 'e') || (*s == 'E'))
  63   {
  64     s++;
  65     if (*s == '+')
  66       s++;
  67     else if (*s == '-')
  68     {
  69       s++;
  70       esign = -1;
  71     }
  72     if ((*s < '0') || (*s > '9'))
  73     {
  74       if (sret)
  75         *sret = (char *)s;
  76       return r;
  77     }
  78
  79     while ((*s >= '0') && (*s <= '9'))
  80     {
  81       e *= 10;
  82       e += *s - '0';
  83       s++;
  84     }
  85   }
  86
  87   if (esign < 0)
  88     for (i = 1; i <= e; i++)
  89       r *= 0.1L;
  90   else
  91     for (i = 1; i <= e; i++)
  92       r *= 10.0;
  93
  94   if (sret)
  95     *sret = (char *)s;
  96   return r * sign;
  97 }