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- Dictionaryuseful/ˈjuːsf(ʊ)l/
adjective
- 1. able to be used for a practical purpose or in several ways: "aspirins are useful for headaches" Similar Opposite
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2. #define is used to define some of the text substitutions performed by the preprocessor. If you write. and then refer to foo in your program, all instances of the identifier foo will be turned into the number 417. (But foo4 will remain as foo4, for instance.) then an occurrence of twice(417) in your program will turn into 417,417.
Nov 27, 2015 · The #define directive has two common uses. The first one, is control how the compiler will act. To do this, we also need #undef, #ifdef and #ifndef. (and #endif too...) You can make "compiler logic" this way. A common use is to activate or not a debug portion of the code, like that: #ifdef DEBUG. //debug code here.
Nov 14, 2015 · 5. A short list of #define use guidelines for C++, points 2, 4, 6 and 7 actually address the question: Avoid them. Use them for the the common "include guard" pattern in header files. Otherwise, don't use them, unless you can explain, why you are using #define and not const, constexpr, or an inline or a template function, etc, instead.
the substituted value need not be legal (or discrete) in the context where the #define is created, as it's evaluated at each point of use, so you can reference not-yet-declared objects, depend on "implementation" that needn't be pre-included, create "constants" such as { 1, 2 } that can be used to initialise arrays, or #define MICROSECONDS *1E-6 etc. (definitely not recommending this!)
Nov 27, 2015 · The most commonly used is probably WIN32_LEAN_AND_MEAN - it disables rarely used parts of the API. You can find more on MSDN's Using the Windows Headers. I remembered wrong about MSDN listing those defines, so here's list from windows.h: /* If defined, the following flags inhibit definition. * of the indicated items.
I can't think of a reason why people shouldn't use it, when appropriate. It is useful in some circumstances, and not in others. I think that because it's an interesting technique, some coders perhaps end up using it more often than they should, without real justification. This has given recursion a bad name in some circles.
Sep 9, 2014 · A tuple is a sequence of values. The values can be any type, and they are indexed by integer, so tuples are not like lists. The most important difference is that tuples are immutable. A tuple is a comma-separated list of values: t = 'p', 'q', 'r', 's', 't'. it is good practice to enclose tuples in parentheses:
Mar 28, 2018 · Most compilers will allow you to define a macro from the command line (e.g. g++ -DDEBUG something.cpp), but you can also just put a define in your code like so: #define DEBUG Some resources: Wikipedia article; C++ specific site; Documentation on GCC's preprocessor; Microsoft reference; C specific site (I don't think it's different from the C++ ...
Closed 6 years ago. The C preprocessor is justifiably feared and shunned by the C++ community. In-lined functions, consts and templates are usually a safer and superior alternative to a #define. The following macro: #define SUCCEEDED(hr) ((HRESULT)(hr) >= 0) is in no way superior to the type safe:
Mar 17, 2009 · Macros are still used to make up for deficits in the language's expressive capability, such as for "wrappers" around header files. Here's an enumeration of the common uses for macros, and the corresponding feature in D: Defining literal constants: The C Preprocessor Way. #define VALUE 5. The D Way.
