Changes the default size of the long
double data type.
This content is specific to C++; it does not apply to
The default size of the long double data type is 64
This option changes the default size of the long double
data type to 80 bits.
However, the alignment requirement of the data type is 16
bytes, and its size must be a multiple of its alignment, so the size of a long
double on Windows* is also 16 bytes. Only the lower 10 bytes (80 bits) of the
16 byte space will have valid data stored in it.
Note that the Microsoft* compiler and Microsoft*-provided
library routines (such as
math functions) do not provide support for
80-bit floating-point values. As a result, this option should only be used when
referencing symbols within parts of your application built with this option or
symbols in libraries that were built with this option.