strtof man page on CentOS

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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);

       #define _XOPEN_SOURCE=600   /* or #define _ISOC99_SOURCE */
       #include <stdlib.h>

       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 pos‐
       sibly 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 speci‐
       fies 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	 char‐
       acter  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
       C89 describes strtod(), C99 describes the other two functions.

NOTES
       Since 0 can legitimately be returned on both success and	 failure,  the
       calling	program should set errno to 0 before the call, and then deter‐
       mine if an error occurred by checking  whether  errno  has  a  non-zero
       value after the call.

EXAMPLE
       See  the example on the strtol(3) manual page; the use of the functions
       described in this manual page is similar.

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

Linux				  2001-06-07			     STRTOD(3)
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