Java doesn’t have a preprocessor – so the simple answer is that you can’t. This sort of thing is normally handled in Java using Dependency Injection – which is both more powerful and more flexible. http://www.vogella.com/articles/DependencyInjection/article.html
Both expressions are false, so the code is never compiled. Here are potential explanations for why the programmer did not want to use the obvious #if 0 preprocessor directive to disable a section of code: the programmer did not want grep ‘#if 0’ to find his code snippet. the local coding conventions disallow #if 0 … Read more
It tells the compiler where the following line actually came from. It’s usually only the C preprocessor that adds these, for example, when including a file, it tells the compiler (which is basically only seeing one stream of data) that we’re looking at a different file. This may sound strange, but the preprocessor simply inserts … Read more
I wasn’t trying enough, I found out #if !myFlag #endif works well !
Try: #if defined(_WIN32) || defined(_WIN64) // do stuff #endif The defined macro tests whether or not a name is defined and lets you apply logical operators to the result.
you could try: #if !(SOME_VARIABLE) // Do something #endif
It is possible to insert a hash token into the preprocessed token stream. You can do it as follows: #define MACRO(hash, name) hash include name MACRO(#,”hello”) —expands to: # include “hello” However, the standard explicitly rules out any further analysis of such line for the existence of preprocessing directives [cpp.rescan]: The resulting completely macro-replaced preprocessing … Read more
It’s the same as for DEBUG, assuming that you’ve defined a build configuration that lists TEST in the “Conditional compilation symbols” text box (under project properties > Build tab; this is a space-delimited list). For code that you only want to run in the TEST build configuration: #if TEST // … #endif And for code … Read more
The 199711L stands for Year=1997, Month = 11 (i.e., November of 1997) — the date when the committee approved the standard that the rest of the ISO approved in early 1998. For the 2003 standard, there were few enough changes that the committee (apparently) decided to leave that value unchanged. For the 2011 standard, it’s … Read more
__cplusplus should be defined as 199711L in pre-C++11 compilers, 201103L in those suporting C++11. Whether this is much help in practice is another question: most compilers are only halfway there, so shouldn’t be defining it as 201103L, even if they support the features you are interested in. And it’s not unheard of for a compiler … Read more