NAME

strtod, atof − convert string to double-precision number

SYNOPSIS

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

double atof(str)
char ∗str;

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(3)), then an optional sign, then a string of digits optionally containing a decimal point, then an optional e or E followed by an optional sign, followed by an integer. 

If the value of ptr is not (char ∗∗)NULL, a pointer to the character terminating the scan is returned in the location pointed to by ptr. If no number can be formed, ∗ptr is set to str, and zero is returned.

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

SEE ALSO

ctype(3), scanf(3S), strtol(3). 

DIAGNOSTICS

If the correct value would cause overflow, ±HUGE is returned (according to the sign of the value).  If the correct value would cause underflow, zero is returned. 

BUGS

errno is not set when overflow or underflow. 

NEWS-OSRelease 4.1C