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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
       character, 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)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | SEE ALSO

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