|
- Is it possible to use a if statement inside #define?
There are multiple problems with your macro: it expands to a statement, so you cannot use it as an expression the arguments are not properly parenthesized in the expansion: invoking this macro with anything but variable names or constants will produce problems the arguments are evaluated multiple times: if you invoke the macro with arguments that have side effects, such as SUM_A(a(), b()) or
- How do I show the value of a #define at compile-time?
I know that this is a long time after the original query, but this may still be useful This can be done in GCC using the stringify operator "#", but it requires two additional stages to be defined first #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 4 Stringification in the gcc online
- c++ - Why use #define instead of a variable - Stack Overflow
What is the point of #define in C++? I've only seen examples where it's used in place of a "magic number" but I don't see the point in just giving that value to a variable instead
- Why are #ifndef and #define used in C++ header files?
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?
- c++ - What does ## in a #define mean? - Stack Overflow
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
- Define a preprocessor macro through CMake - Stack Overflow
How do I define a preprocessor variable through CMake? The equivalent code would be #define foo
- ¿Que significa el operador #define? - Stack Overflow en español
Pero en una forma más compleja, #define admite "parámetros" que pueden formar parte de la sutitución resultante Eso permite usarlo para escribir una especie de "funciones", que en realidad no son funciones porque el preprocesador se ocupa de expandir su uso (es decir, reemplazarlo por su correspondiente sustitución poniendo los parámetros donde corresponda) Por ejemplo si en tu código
- c++ - Declaring a function using #define - Stack Overflow
The #define version is still a macro The code is expanded at the invocation site It has all the expected problems (with macros) including namespace pollution and unexpected parameter behaviour
|
|
|