STRTOD(3)							 Library functions							 STRTOD(3)

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 initial 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  isspace(3),	an  optional  plus
       (``+'') or minus sign (``-'') and then either (i) a decimal number, or (ii) a hexadecimal number, or (iii) an infinity, or (iv) a NAN (not-
       a-number).

       A decimal number consists of a nonempty sequence of decimal digits possibly containing a radix character (decimal point, locale	dependent,
       usually	``.''), optionally followed 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'' followed by a nonempty sequence of hexadecimal digits possibly containing a radix char-
       acter,  optionally  followed  by  a  binary exponent. A binary exponent consists of a ``P'' or ``p'', followed by an optional plus or minus
       sign, followed by a non-empty sequence of decimal digits, and indicates 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'', disregarding 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.

CONFORMING TO

       ANSI C describes strtod, C99 describes the other two functions.

SEE ALSO

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

Linux								    2001-06-07								 STRTOD(3)