Switching between float and double precision at compile time

Question

Where should I look at if I want to switch between float and double precision at compile time. Its like, if user wants everything in float instead of double precision how I

Answer 1

If it is OK to make the switch at compile time, a simple typedef would do:

#ifdef USE_DOUBLES
typedef double user_data_t;
#else
typedef float user_data_t;
#endif

Use user_data_t in your code, and set USE_DOUBLES if you want doubles at compile time:

g++ -DUSE_DOUBLES=1 myprogram.cpp