1  #define P(a, b) P1(a,b)
       2  #define P1(a,b) a##b
       3  
       4  #define FLT_MIN_EXP (-125)
       5  #define DBL_MIN_EXP (-1021)
       6  
       7  #define MIN_EXP P(FLT,_MIN_EXP)
       8  
       9  #define FLT FLT
      10  int f1 = MIN_EXP;
      11  
      12  #undef FLT
      13  #define FLT DBL
      14  int f2 = MIN_EXP;