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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.
May 15, 2011 · 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++ ...
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.
Recursion is solving a problem with a function that calls itself. A good example of this is a factorial function. Factorial is a math problem where factorial of 5, for example, is 5 * 4 * 3 * 2 * 1. This function solves this in C# for positive integers (not tested - there may be a bug).
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.
Oct 31, 2008 · 3. Unions are used when you want to model structs defined by hardware, devices or network protocols, or when you're creating a large number of objects and want to save space. You really don't need them 95% of the time though, stick with easy-to-debug code. answered Oct 31, 2008 at 3:59.
Sep 9, 2014 · 1. A tuple is useful for storing multiple values.. As you note a tuple is just like a list that is immutable - e.g. once created you cannot add/remove/swap elements. One benefit of being immutable is that because the tuple is fixed size it allows the run-time to perform certain optimizations.
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:
Jan 17, 2011 · Maintainers to understand algorithms others have written and correctly make changes. Enums improve both likelihood of correctness and readability without writing a lot of boilerplate. If you are willing to write boilerplate, then you can "simulate" enums: private Color() {} // Prevent others from making colors.
The macro you posted from GCC (min and max) is an example of this, they use the global variables _a and _b to avoid the risk of double evaluation (like in max(x++,y++)) (well, they use GCC extensions but the concept is the same). I like using macros where it helps to make things more clear but they are a sharp tool!
