ATOF(3) NEWLIB ATOF(3)NAME
2.7 `atof', `atoff'--string to double or float
SYNOPSIS
#include <stdlib.h>
double atof(const char *S);
float atoff(const 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 char‐
acter. 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 imple‐
mented 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'.
SEE ALSOatof is part of the library. The full documentation for is maintained
as a Texinfo manual. If info and are properly installed at your site,
the command
info
will give you access to the complete manual.
NEWLIB April 2010 ATOF(3)
