STRTOD - phpMan

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  con-
       taining a radix character (decimal point, locale dependent, usually ‘‘.’’), option-
       ally 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)

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