rom/dos/strtolong.c

   1 /*
   2     Copyright © 1995-2008, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Convert a string into a long
   6     Lang: english
   7 */
   8
   9 /*****************************************************************************
  10
  11     NAME */
  12 #include <proto/dos.h>
  13
  14         AROS_LH2I(LONG, StrToLong,
  15
  16 /*  SYNOPSIS */
  17         AROS_LHA(CONST_STRPTR, string, D1),
  18         AROS_LHA(LONG *, value,  D2),
  19
  20 /*  LOCATION */
  21         struct DosLibrary *, DOSBase, 136, Dos)
  22
  23 /*  FUNCTION
  24         Convert a string to a long number.
  25
  26     INPUTS
  27         string - The value to convert
  28         value - The result is returned here
  29
  30     RESULT
  31         How many characters in the string were considered when it was
  32         converted or -1 if no valid number could be found.
  33
  34     NOTES
  35         The routine doesn't check if the number if too large.
  36
  37     EXAMPLE
  38         // Valid number are: 5, -1, +3, +0007, etc.
  39
  40     BUGS
  41
  42     SEE ALSO
  43
  44     INTERNALS
  45
  46 *****************************************************************************/
  47 {
  48     AROS_LIBFUNC_INIT
  49
  50     LONG sign=0, v=0;
  51     CONST_STRPTR s=string;
  52
  53     /* Skip leading whitespace characters */
  54     while(*s==' '||*s=='\t')
  55         s++;
  56
  57     /* Swallow sign */
  58     if(*s=='+'||*s=='-')
  59         sign=*s++;
  60
  61     /* If there is no number return an error. */
  62     if(*s<'0'||*s>'9')
  63     {
  64         *value=0;
  65         return -1;
  66     }
  67
  68     /* Calculate result */
  69     do
  70         v=v*10+*s++-'0';
  71     while(*s>='0'&&*s<='9');
  72
  73     /* Negative? */
  74     if(sign=='-')
  75         v=-v;
  76
  77     /* All done. */
  78     *value=v;
  79     return s-string;
  80     AROS_LIBFUNC_EXIT
  81 } /* StrToLong */