Define tone deaf. You'll need to complete a few actions and gain 15 reputation points before being able to upvote. If it is set there, this sounds like a stale preprocessed header thing. You are passing a variable to a template, which is fine. 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. I have been seeing code like this usually in the start of header files: #ifndef HEADERFILE_H #define HEADERFILE_H And at the end of the file is #endif What is the purpose of this? What is define ( [ , function ]) in JavaScript? [duplicate] Asked 12 years, 5 months ago Modified 2 years, 10 months ago Viewed 240k times How do I define a function with optional arguments? Asked 13 years, 8 months ago Modified 1 year, 4 months ago Viewed 1. Jun 18, 2012 · #define WIDTH 10 is a preprocessor directive that allows you to specify a name (WIDTH) and its replacement text (10). Mar 4, 2017 · #define simply substitutes a name with its value. Feb 15, 2025 · Revising my answer based on the updated question. You're correct that using #define for symbols and (please don't do it) macros, is not a good use-case. The following statements are equivalent: condition: succeeded() # equivalent to: condition: $[ succeeded() ] Variables are also only evaluated at runtime. So is there any solution? The #define directive is a preprocessor directive; the preprocessor replaces those macros by their body before the compiler even sees it. What's reputation and how do I get it? Instead, you can save this post to reference later. I know that this is a long time after the original query, but this may still be useful. Oct 30, 2013 · The main use-case for #define is for conditional compilation (where it can be very useful). Here’s how you can use it, but lots to unpack to understand why. This can be done in GCC using the stringify operator "#", but it requires two additional stages to be defined first. Manually delete everything that is not a source file, project file or resource and build again. Jan 24, 2024 · How do I define a preprocessor variable through CMake? The equivalent code would be #define foo. Nov 4, 2009 · Which one is better to use among the below statements in C? static const int var = 5; or #define var 5 or enum { var = 5 }; How do I define a function with optional arguments? Asked 13 years, 8 months ago Modified 1 year, 4 months ago Viewed 1. Oh Mar 4, 2017 · #define simply substitutes a name with its value. A const variable declaration declares an actual variable in the language, which you can use well, like a real variable: take its address, pass it around, use it, cast/convert it, etc. The compiler never actually sees a macro name at all, what it sees is the replaced text. When referencing variables The #define directive is a preprocessor directive; the preprocessor replaces those macros by their body before the compiler even sees it. 4 Stringification in the gcc online Jul 30, 2014 · Check what Michael said: in the build log, is there a _AFXDLL? Do not define it manually, it is added when you set "Use MFC in a shared DLL". Oh May 10, 2010 · 0 in C or C++ #define allows you to create preprocessor Macros. A condition is a runtime expression. #define XSTR(x) STR(x) #define STR(x) #x The value of a macro can then be displayed with: #pragma message "The value of ABC: " XSTR(ABC) See: 3. 2m times I have been seeing code like this usually in the start of header files: #ifndef HEADERFILE_H #define HEADERFILE_H And at the end of the file is #endif What is the purpose of this? Oct 30, 2013 · The main use-case for #define is for conditional compilation (where it can be very useful). Furthermore, a #define 'd constant may be used in the preprocessor: you can use it with #ifdef to do conditional compilation based on its value, or use the stringizing operator # to get a string with its value. (# is not an allowed character in #define). Upvoting indicates when questions and answers are useful. . 2m times I have been seeing code like this usually in the start of header files: #ifndef HEADERFILE_H #define HEADERFILE_H And at the end of the file is #endif What is the purpose of this? Jun 18, 2012 · #define WIDTH 10 is a preprocessor directive that allows you to specify a name (WIDTH) and its replacement text (10). Jun 18, 2012 · #define WIDTH 10 is a preprocessor directive that allows you to specify a name (WIDTH) and its replacement text (10). Think of it as an automatic search and replace of your source code. The preprocessor parses the source file and each occurrence of the name is replaced by its associated text. 2m times I am trying to write something like this: #define COV_ON(x) \ #ifdef COVERAGE_TOOL \ _Pragma (COVERAGE #x) #endif Is there any way to define COV_ON like this? I know what I have done above is wrong as I can't have #ifdef inside #define. iyi 9gtjrn rew cdmuvyrc zz tp tnseu ap0 u8ku6y 5vqhfkv