NAME

strtod, atof, nl_strtod, nl_atof − convert string to double-precision number

SYNOPSIS

double strtod (str, ptr)
char ∗str, ∗∗ptr;

double atof (str)
char ∗str;

double nl_strtod (str, ptr, langid)
char ∗str, ∗∗ptr;
int langid;

double nl_atof (str, langid)
char ∗str;
inl langid;

DESCRIPTION

Strtod returns as a double-precision floating-point number the value represented by the character string pointed to by str. The string is scanned up to the first unrecognized character.

Strtod recognizes an optional string of “white-space” characters (as defined by isspace in ctype(3C)), then an optional sign, then a string of digits optionally containing a radix character, then an optional e or E followed by an optional sign or space, followed by an integer.  The radix character is determined by the loaded NLS environment (see nl_init(3C)). If nl_init has not been called successfully, the default NLS environment, ­"n-computer" (see langid(5)), is used.  The default environment specifies a period (.) as the radix character.

If the value of ptr is not (char ∗∗)NULL, the variable to which it points is set to point at the character after the last number, if any, that was recognized.  If no number can be formed, ∗ptr is set to str, and zero is returned.

Atof(str) is equivalent to strtod (str, (char ∗∗)NULL). 

Nl_strtod and nl_atof are similar to the above routines, but first call langinit (see nl_init(3C)) to load the NLS environment specified by langid.

DIAGNOSTICS

If the correct value would cause overflow, ±HUGE is returned (according to the sign of the value), and errno is set to ERANGE.  HUGE_VAL may be used instead of HUGE. 

If the correct value would cause underflow, zero is returned and errno is set to ERANGE. 

WARNINGS

Nl_strtod and nl_atof are provided for historical reasons only.  Their use is not recommended.  Use strtod and atof instead. 

DEPENDENCIES

Series 500
NLS radix is not supported by strtod and atof. Continue to use nl_strtod and nl_atof instead. 

AUTHOR

Strtod was developed by AT&T and HP. 

SEE ALSO

ctype(3C), nl_init(3C), scanf(3S), strtol(3C), hpnls(5), langid(5). 

INTERNATIONAL SUPPORT

8-bit data. 

Hewlett-Packard Company  —  Version B.1,  May 11, 2021