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How to generate random variable names in C++ using macros?


I'm creating a macro in C++ that declares a variable and assigns some value to it. Depending on how the macro is used, the second occurrence of the macro can override the value of the first variable. For instance:

#define MY_MACRO int my_variable_[random-number-here] = getCurrentTime();

The other motivation to use that is to avoid selecting certain name to the variable so that it be the same as a name eventually chosen by the developer using the macro.

Is there a way to generate random variable names inside a macro in C++?

-- Edit --

I mean unique but also random once I can use my macro twice in a block and in this case it will generate something like:

int unique_variable_name;
...
int unique_variable_name;

In this case, to be unique both variable names have to be random generated.


Solution

  • Add M4 to your build flow? This macro language has some stateful capabilities, and can successfully be intermingled with CPP macros. This is probably not a standard way to generate unique names in a C environment, though I've been able to sucessfully use it in such a manner.

    You probably do not not want random, BTW, based on the way you posed your question. You want unique.

    You could use __FILE__ and __LINE__ in the macro expansion to get you the uniqueness you seem to be going for... those metavariables get defined within the source file context, so be careful to make sure you get what you are looking for (e.g., perils of more than one macro on the same line).