C4424: # in substitution list must be followed by name of formal parameter

[FATAL]

There is a problem with the '#' operator during preprocessing, because there is no legal name as formal parameter specified.

  #define cat(a,b) a #

  

  void foo(void) {

  

    i = cat(3,3);

  

  }

  

Check your macro definition or usage. Generate a preprocessor output (option -Lp) to find the problem.