Developer Guide and Reference

Contents

Qlong-double

Changes the default size of the long double data type.
This content is specific to C++; it does not apply to
DPC++
.

Syntax

Linux:
None
Windows:
/Qlong-double
Arguments
None
Default
OFF
The default size of the long double data type is 64 bits.
Description
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
printf
or
long double
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.
IDE Equivalent
None
Alternate Options
None

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.