What does ## mean for the C (C++) preprocessor? - Stack Overflow
网页2016年2月20日 — 6. ## is Token Pasting Operator. The double-number-sign or "token-pasting" operator (##), which is sometimes called the "merging" operator, is used in both object-like and function-like macros. It permits separate tokens to be joined into a single token and therefore cannot be the first or last token in the macro definition.
Can boolean operators be used with the preprocessor?
网页FYI, identifiers/names, including preprocessor symbols, beginning with an underscore followed by a capital letter (or beginning with two underscores) are reserved to the implementation by the C and C++ standards; they shouldn't …
gcc - How to view C preprocessor output? - Stack Overflow
网页gcc -E file.c. or. g++ -E file.cpp. will do this for you. The -E switch forces the compiler to stop after the preprocessing phase, spitting all it’s got at the moment to standard output. Note: Surely you must have some #include directives. The included files get preprocessed, too, so you might get lots of output.
What does preprocessing exactly mean in compiler
网页2016年3月14日 — The preprocessor eliminates most lines that start with # (it only leaves #line directives behind and its own abbreviated variants on #line behind to tell the compiler where the source came from). The compiler proper then sees the result of the pre-processing and compiles the source code that is defined.
Is there a portable way to print a message from the C preprocessor?
网页2010年9月30日 — Another solution is to use comments plus a shell script to process them. This takes some discipline (or a shell script which catches typos). For example, I add comments formatted //TODO and then a shell script which collects all of them into a report. For more complex use cases, you can try to write your own simple preprocessor.
C preprocessor #if expression - Stack Overflow
网页2017年3月16日 — The preprocessor looks to see if there's a macro defined for c. Since there isn't, it evaluates the following expression: #if 0==1. which is false of course. Since you don't appear to use the variable c in your program, you can do the following to get behavior in line with what you're trying: #define C 1. #if C==1.
How do I see a C/C++ source file after preprocessing in Visual …
网页2008年11月10日 — CPIP is a new C/C++ preprocessor written in Python. If you want a detailed visual representation of a preprocessed file, give it a shot. CPIP is a C/C++ pre-processor implemented in Python. Most pre-processors regard pre-processing as a dirty job that just has to be done as soon as possible.
Define a preprocessor macro through CMake - Stack Overflow
网页2012年1月26日 — 1.) target_compile_definitions. If you are using CMake 3.X your first choice for adding a preprocessor macro should be target_compile_definitions. The reason you should prefer this approach over any other approach is because it granularity is target based. IE the macro will only be added to your exe/library.
How do I check OS with a preprocessor directive?
网页2008年9月27日 — 2. Use #define OSsymbol and #ifdef OSsymbol where OSsymbol is a #define 'able symbol identifying your target OS. Typically you would include a central header file defining the selected OS symbol and use OS-specific include and library directories to compile and build.
How do I show the value of a #define at compile-time?
网页The preprocessor understands quoted strings and handles them differently from normal text. String concatenation is an example of this special treatment. The message pragma requires an argument that is a quoted string. When there is more than one component to the argument then they must all be strings so that string concatenation can be applied.