strtod - convert ASCII string to double
double strtod(const char *nptr,
The strtod function converts the initial portion of the string
pointed to by nptr to double representation.
The expected form of the string
is an optional plus ("+") or
minus sign ("-") followed by a sequence of digits optionally
containing a decimal-point character, optionally followed by an
exponent. An exponent consists of an "E" or "e", followed by
an optional plus or minus sign, followed by a sequence of digits.
Leading white-space characters
in the string (as defined by the
isspace(3) function) are skipped.
The strtod function returns 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
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.
Overflow or underflow occurred.
atof(3), atoi(3), atol(3), strtol(3), strtoul(3)