STRTOD(3)                 OpenBSD Programmer's Manual                STRTOD(3)

NAME
     strtod, strtof, strtold - convert ASCII string to double, float or long
     double

SYNOPSIS
     #include <math.h>
     #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() function converts the initial portion of the string pointed
     to by nptr to double representation.  The strtof() function converts the
     initial portion of the string pointed to by nptr to float representation.
     The strtold() function converts the initial portion of the string pointed
     to by nptr to long 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 whitespace characters in the string (as defined by the isspace(3)
     function) are skipped.

RETURN VALUES
     The strtod(), strtof() and strtold() 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 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.

SEE ALSO
     atof(3), atoi(3), atol(3), strtol(3), strtoul(3)

STANDARDS
     The strtod() function conforms to ANSI X3.159-1989 (``ANSI C'').  The
     strtof() and strtold() functions conform to ANSI/ISO/IEC 9899-1999
     (``ANSI C99'').

OpenBSD 4.9                   September 13, 2008                   OpenBSD 4.9