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/*

FUNCTION

   <<atof>>, <<atoff>>---string to double or float

INDEX

        atof

INDEX

        atoff

ANSI_SYNOPSIS

        #include <stdlib.h>

        double atof(const char *<[s]>);

        float atoff(const char *<[s]>);

TRAD_SYNOPSIS

        #include <stdlib.h>

        double atof(<[s]>)

        char *<[s]>;

        float atoff(<[s]>)

        char *<[s]>;

DESCRIPTION

<<atof>> converts the initial portion of a string to a <<double>>.

<<atoff>> converts the initial portion of a string to a <<float>>.

The functions parse the character string <[s]>,

locating a substring which can be converted to a floating-point

value. The substring must match the format:

. [+|-]<[digits]>[.][<[digits]>][(e|E)[+|-]<[digits]>]

The substring converted is the longest initial

fragment of <[s]> that has the expected format, beginning with

the first non-whitespace character.  The substring

is empty if <<str>> is empty, consists entirely

of whitespace, or if the first non-whitespace character is

something other than <<+>>, <<->>, <<.>>, or a digit.

<<atof(<[s]>)>> is implemented as <<strtod(<[s]>, NULL)>>.

<<atoff(<[s]>)>> is implemented as <<strtof(<[s]>, NULL)>>.

RETURNS

<<atof>> returns the converted substring value, if any, as a

<<double>>; or <<0.0>>,  if no conversion could be performed.

If the correct value is out of the range of representable values, plus

or minus <<HUGE_VAL>> is returned, and <<ERANGE>> is stored in

<<errno>>.

If the correct value would cause underflow, <<0.0>> is returned

and <<ERANGE>> is stored in <<errno>>.

<<atoff>> obeys the same rules as <<atof>>, except that it

returns a <<float>>.

PORTABILITY

<<atof>> is ANSI C. <<atof>>, <<atoi>>, and <<atol>> are subsumed by <<strod>>

and <<strol>>, but are used extensively in existing code. These functions are

less reliable, but may be faster if the argument is verified to be in a valid

range.

Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,

<<lseek>>, <<read>>, <<sbrk>>, <<write>>.

*/

#include <stdlib.h>

#include <_ansi.h>

double

_DEFUN (atof, (s),

        _CONST char *s)

{

  return strtod (s, NULL);

}