atof - convert a string to a double-precision number
double atof(const char *str);
[CX] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2008 defers to the ISO C standard.
The call atof(str) shall be equivalent to:strtod(str,(char **)NULL),
except that the handling of errors may differ. If the value cannot be represented, the behavior is undefined.
The atof() function shall return the converted value if the value can be represented.
No errors are defined.
The atof() function is subsumed by strtod() but is retained because it is used extensively in existing code. If the number is not known to be in range, strtod() should be used because atof() is not required to perform any error checking.
First released in Issue 1. Derived from Issue 1 of the SVID.
return to top of page