Nov 27, 2015 · In the normal C or C++ build process the first thing that happens is that the PreProcessor runs, the preprocessor looks though the source files for preprocessor directives like #define or #include and then performs simple operations with them. in the case of a #define directive the preprocessor does simple text based substitution.

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++ ...

In other words, when the compiler starts building your code, no #define statements or anything like that is left. A good way to understand what the preprocessor does to your code is to get hold of the preprocessed output and look at it.

Jul 9, 2018 · #define is part of something called the "preprocessor." Essentially, this is the code that is processed before the C document is compiled. Most of the preprocessor code is in a file with a ".h" extension (which is why you may have seen that when importing libraries). The preprocessor language is primitive.

I'm trying to make a macro with the following formula: (a^2/(a+b))*b, and I want to make sure that the there will be no dividing by zero.

Aug 19, 2008 · #define is used to define compile-time constants that you can use with #if to include or exclude bits of code. #define USEFOREACH #if USEFOREACH foreach(var item in items) { #else for(int i=0; i < items.Length; ++i) { var item = items[i]; //take item #endif doSomethingWithItem(item); }

The spaces are significant. You created a variable named 'location ' with a value of ' "bob"'.Note - enclosing single quotes were added to show location of space.

I see this being used all the time in JavaScript: define(['param1', 'param2'], function() { }); What is the define function?

Jul 12, 2011 · One does not define arrays, or any other thing. You can, however, create multidimensional sequences, as the answers here show. Remember that python variables are untyped, but values are strongly typed. –

Oct 28, 2009 · #define is a compiler pre processor directive and should be used as such, for conditional compilation etc.. E.g. where low level code needs to define some possible alternative data structures for portability to specif hardware. It can produce inconsistent results depending on the order your modules are compiled and linked.