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- NAME
- strtod, strtof, strtold - convert ASCII string to floating
point number
- SYNOPSIS
- #include <stdlib.h>
double strtod(const char *nptr, char **endptr);
float strtof(const char *nptr, char **endptr);
long double strtold(const char *nptr, char **endptr);
- DESCRIPTION
- The strtod, strtof, and strtold functions convert the ini
tial portion of the string pointed to by nptr to double,
float, and long double representation, respectively.
The expected form of the (initial portion of the) string
is optional leading white space as recognized by is
space(3), an optional plus (``+'') or minus sign (``-'')
and then either (i) a decimal number, or (ii) a hexadeci
mal number, or (iii) an infinity, or (iv) a NAN (not-a-
number).
A decimal number consists of a nonempty sequence of deci
mal digits possibly containing a radix character (decimal
point, locale dependent, usually ``.''), optionally fol
lowed by a decimal exponent. A decimal exponent consists
of an ``E'' or ``e'', followed by an optional plus or
minus sign, followed by a non-empty sequence of decimal
digits, and indicates multiplication by a power of 10.
A hexadecimal number consists of a ``0x'' or ``0X'' fol
lowed by a nonempty sequence of hexadecimal digits possi
bly containing a radix character, optionally followed by a
binary exponent. A binary exponent consists of a ``P'' or
``p'', followed by an optional plus or minus sign, fol
lowed by a non-empty sequence of decimal digits, and indi
cates multiplication by a power of 2. At least one of
radix character and binary exponent must be present.
An infinity is either ``INF'' or ``INFINITY'', disregard
ing case.
A NAN is ``NAN'' (disregarding case) optionally followed
by `(', a sequence of characters, followed by ')'. The
character string specifies in an implementation-dependent
way the type of NAN.
- RETURN VALUE
- These functions return the converted value, if any.
If endptr is not NULL, a pointer to the character after
the last character used in the conversion is stored in the
location referenced by endptr.
If no conversion is performed, zero is returned and the
value of nptr is stored in the location referenced by
endptr.
If the correct value would cause overflow, plus or minus
HUGE_VAL (HUGE_VALF, HUGE_VALL) is returned (according to
the sign of the value), and ERANGE is stored in errno. If
the correct value would cause underflow, zero is returned
and ERANGE is stored in errno.
- ERRORS
- ERANGE Overflow or underflow occurred.
- IMPLEMENTATION for apeNEXT:
- done with some restrictions:
- endptr contains (if defined) a pointer to a location in some 'virtual' array of char that is located at the same address as the packed string nptr.
I.e. in order to find the invalid character position, one has to calculate the difference between endptr and nptr. - This implementation is bases in the one in uClibc. Changes include removal of all locale and Wchar stuff and the wrapper functions.
- OPTIMIZATIONS for apeNEXT:
- None so far.
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1.3.5