C Preprocessor generate macros by concatenation and stringification [duplicate]

Answer 1

Just use #if / #else / #endif

#if (I2C_MODULE == 0)
#define I2C_MODULE_BASE I2C0_BASE
#define I2C_MODULE_NVIC INT_I2C0
#elif (I2C_MODULE == 1)
#define I2C_MODULE_BASE I2C1_BASE
#define I2C_MODULE_NVIC INT_I2C1
#else
#error Unknown configuration
#endif