INFO: Predefined Identifiers in Microsoft C and C++
ID: Q65472
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The information in this article applies to:
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The Microsoft C/C++ Compiler (CL.EXE)
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Microsoft C for MS-DOS, versions 6.0, 6.0a, 6.0ax
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Microsoft C for OS/2, versions 6.0, 6.0a
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Microsoft C/C++ for MS-DOS
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Microsoft Visual C++ for Windows, 16-bit edition, versions 1.0, 1.5
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Microsoft Visual C++, 32-bit Editions, versions 1.0, 2.0, 4.0, 5.0, 6.0
SUMMARY
The information below is from the Microsoft C Compiler versions 6.0,
6.0a, and 6.0ax; C/C++ version 7.0; Visual C++ 1.0 and 1.5 for Windows;
and Visual C++ 1.0 for Windows NT online Help.
The following information can be accessed in C 6.0 and C/C++ 7.0 from
the help on CL.EXE by seeking help on the text "cl" using either the
F1 key from the Programmer's WorkBench (PWB) or by typing "qh cl"
from the MS-DOS or OS/2 command lines. From the "CL Contents" help
screen, select Preprocessor Options, then Predefined Identifiers.
This information can be accessed in Visual C++ for Windows and Visual C++,
32-bit Edition, by searching on _MSC_VER in the Microsoft C/C++ Language
Help.
MORE INFORMATION
The compiler automatically defines identifiers useful in writing
portable programs. You can use these identifiers to compile code
sections conditionally. These identifiers are always defined unless
otherwise stated.
Microsoft Specific
(NOTE: These macros are supported by both the 16-bit and 32-bit
compilers.)
Macro Specifies
------------------------------------------------------------------
_CHAR_UNSIGNED Default char type is unsigned. Macro defined
when /J is specified.
M_I86, _M_I86 Always defined. Identifies target machine as a
member of the 8086 family.
_MSC_VER Microsoft C version; currently defined as 800.
The following symbol was added in C/C++ 7.0:
Macro Specifies
--------------------------------------------------------------------
__cplusplus Macro defined when compiling a C++ program. (This
macro is not defined for the C compiler.)
16-Bit Specific
Macro Specifies
-------------------------------------------------------------------
MSDOS, _MSDOS Always defined. Identifies target operating system
as MS-DOS.
M_I86mM, _M_I86mM Always defined. Member of the I86 processor family.
Memory model type:
m = T Tiny
S Small (default)
C Compact model
M Medium model
L Large model
H Huge model
Macros defined by /AT, /AS, /AC, /AM, /AL, and /AH
respectively.
M_I8086, _M_I8086 8088 or 8086 processor; default or defined when /G0
is specified.
M_I286, _M_I286 80286 processor. Macro defined when /G1 or /G2 is
specified.
NO_EXT_KEYS Disables Microsoft-specific language extensions
and extended keywords; defined only with /Za
option.
_QC Supported for compatibility with Microsoft C version
6.0. The _FAST macro (or /f) is the default and is
the recommended alternative.
The following symbols were added in C/C++ 7.0:
Macro Specifies
-------------------------------------------------------------------
_DLL Code for run-time library as a dynamic-link library.
Defined when /MD is specified.
_FAST Fast-Compile. Macro defined when /f is specified
Supersedes _QC, which is still supported but not
recommended. Using /Od causes CL to compile your
program with /f. The /f option compiles source files
without any default optimizations.
__STDC__ Full conformance with the ANSI C standard. Defined
the integer constant 1 only if the /Za command-line
option is given; otherwise is undefined.
_PCODE Defined for sections of code that are compiled as
p-code. Macro defined when /Oq is enabled.
_WINDLL Windows protected-mode dynamic-link library is
selected with /GD.
_WINDOWS Windows protected-mode is selected with /GA, /Gw,
/GW, /Mq, or /GD.
32-Bit Specific
The following symbols were added in Visual C++, 32-bit Edition, version
1.0:
Macro Specifies
----- ---------
_DLL Defined when Multithreaded using DLL (/MD or /MDd)
is specified.
_M_IX86 Defined as 300 for the 80386 processor (/G3 option),
as 400 for the 80486 (/G4) processor, as 500
for the Pentium processor (/G5), and as 600 for
Pentium Pro and Pentium II processors (/G6).
_MT Defined when Multithreaded (/MD, /MDd, /MT, or /MTd)
_WIN32 Defined for WIN32 applications. Always defined.
Microsoft specific.
The following symbols were added in Visual C++, 32-bit Edition, version
4.0:
Macro Specifies
----- ---------
_CPPRTTI Defined for code compiled with Enable Run-Time Type
Information (/GR).
_CPPUNWIND Defined for code compiled with Enable Exception
Handling (/GX).
The _MSC_VER macro will have one of the following values depending upon
the particular Microsoft compiler:
Compiler _MSC_VER value
-------- --------------
C Compiler version 6.0 600
C/C++ compiler version 7.0 700
Visual C++, Windows, version 1.0 800
Visual C++, 32-bit, version 1.0 800
Visual C++, Windows, version 2.0 900
Visual C++, 32-bit, version 2.x 900
Visual C++, 32-bit, version 4.0 1000
Visual C++, 32-bit, version 5.0 1100
Visual C++, 32-bit, version 6.0 1200
NOTE: If a predefined identifier has two forms, with and without an
underscore, the command-line driver defines both if you specify the
/Ze option (compile for Microsoft extensions). It defines only the
leading underscore form if you specify the /Za option (compile for
ANSI compatibility).
Additional query words:
8.00 8.00c 9.00
Keywords : kbCompiler kbVC100 kbVC150 kbVC200 kbVC400 kbVC500 kbVC600
Version :
Platform : MS-DOS NT OS/2 WINDOWS
Issue type : kbinfo