(In Cat., 81, 25-34) emphasizes that truth is neither in the things or states of affairs ( pragmata) themselves, nor in the statement itself, but lies in the agreement between the two he gives the simile of the fitting shoe, the fit consisting in a relation between shoe and foot, not to be found in either one by itself.
The _Pragma statement in the example only applies to the line of code that follows it.Where the focus used to lie on body politics, imagining the state as something to be formed with one General Will, we should be looking into politics of pragmatism. For more information, see C multi-line macro on Stack Overflow. while(0) idiom for multi-statement macros so that it can be used as though it were one statement. It creates a pragma directive that suppresses a warning when the condition expression happens to be constant. The following code example demonstrates how the _Pragma keyword could be used in an assert-like macro. A pragma string that isn't recognized is ignored. Quotation marks and back-slashes should be escaped, as shown above. _Pragma ("message( \"the _Pragma way\")") For example: #pragma message("the #pragma way") The string literal should be what you would otherwise put following a #pragma statement. Unlike #pragma, _Pragma allows you to put pragma directives into a macro definition. For C++, it's available in all /std modes, including the default. It's available in C only when you specify the /std:c11 or /std:c17 option. It was introduced into the C standard in C99, and the C++ standard in C++11. _Pragma is similar to the Microsoft-specific _pragma keyword. _hr = DualHandleException(_riidSource, e) \
_pragma(warning(disable:6246)) /*disable _ctlState prefast warning*/ \ĪFX_MANAGE_STATE(pThis->m_pModuleState) \ This code is excerpted from the mfcdual.h header in the ACDUAL sample in "Compiler COM Support Samples": #define CATCH_ALL_DUAL \ The following code example demonstrates how the _pragma keyword can be used in a macro. The #pragma directive isn't usable in a macro definition, because the compiler interprets the number sign character ('#') in the directive as the stringizing operator (#). The difference is, the _pragma keyword is usable inline in a macro definition. The compiler also supports the Microsoft-specific _pragma keyword, which has the same functionality as the #pragma directive. For example, if you specified /Zp8, you can override this compiler setting for specific sections of the code with pack: cl /Zp8 some_file.cpp When a pragma is reached in source code, it overrides the behavior specified by the compiler option. Some pragma directives provide the same functionality as compiler options. The Microsoft C and C++ compilers recognize the following pragma directives:ġ Supported only by the C++ compiler. The compiler issues a warning when it finds a pragma that it doesn't recognize, and continues compilation. \" is replaced with " and \\ is replaced with \. Outer quotes and leading/trailing whitespace are removed. The string-literal is the input to _Pragma. The argument to #pragma is subject to macro expansion. Following #pragma, write any text that the translator can parse as preprocessing tokens. White-space characters can separate the number sign and the word "pragma". The number sign ( #) must be the first non-white-space character on the line that contains the pragma.
The token-string is a series of characters representing a specific compiler instruction and arguments, if any. Or, use one to provide implementation-defined information to the compiler. A pragma can be used in a conditional directive, to provide new preprocessor functionality.
Pragma directives are machine-specific or operating system-specific by definition, and are typically different for every compiler. The #pragma directives offer a way for each compiler to offer machine- and operating system-specific features, while maintaining overall compatibility with the C and C++ languages. Some programs, for example, must exercise precise control over the location of data in memory, or control the way certain functions receive parameters. _pragma( token-string ) // two leading underscores - Microsoft-specific extensionĮach implementation of C and C++ supports some features unique to its host machine or operating system. The standard _Pragma preprocessor operator, introduced in C99 and adopted by C++11, is similar. The Microsoft-specific _pragma keyword enables you to code pragma directives within macro definitions. A line that starts with #pragma specifies a pragma directive. Pragma directives specify machine-specific or operating system-specific compiler features.