Custom print macro, two pairs of parentheses, single parameter macro, specified parameter macro, variable parameter macros

v1--Single-parameter macros

#define DRV_DEBUG 1#if DRV_DEBUG    #define DRV_PRINT(x) printf(x)#else #define DRV_PRINT(x) #endif

This version of Drv_print (x) can only output a single variable--pure string

void foo(){    DRV_PRINT("Driver Initialize Success!");}

Change the Drv_debug macro definition when you do not need to print debug information

#define DRV_DEBUG 0

Of course, you can define it directly.

#define DRV_PRINT printf

But if the macro calls more than one parameter:

void foo(){    DRV_PRINT("Driver Initialize Success: ver %d.%d !", 1, 2);}

The compilation error in the Product code #define DRV_PRINT(x) !

What to do? A way Virgo would never accept括号

void foo(){    DRV_PRINT(("Driver Initialize Success: ver %d.%d !", 1, 2));}

Whether it's debug code or product code, compile OK

v2--Specifying parameter macros

#define DRV_DEBUG 1#if DRV_DEBUG    #define DRV_PRINT(fmt, val1, val2) printf(fmt, val1, val2)#else #define DRV_PRINT(fmt, val1, val2) #endif

If you only need to print a variable, the first 2 parameter is filled with random values, such as

void foo(){    DRV_PRINT("Driver Initialize Success: ver %d !", val1, 2);}

Similarly, if there are 4 parameters, it is:

void foo(){    DRV_PRINT("Driver Initialize Success: ver %d !", val1, 2, 3, 4);}

Silly, but there is no way: (, the VxWorks 5.5 kernel code is the way to do!)

v3--parameter number variable macro

Macros can be declared in C90 and C + + to accept a variable number of arguments, such as ARM编译器 :

#define DRV_DEBUG 1#if DRV_DEBUG    #define DRV_PRINT(fmt, ...) printf(fmt, __VA_ARGS__)#else #define DRV_PRINT(fmt, ...) #endif

Now the DRV_PRINT usage and printf exactly the same, so cool features, C2000编译器 but not support!

aside, note that this feature C90 support, while C90 is a subset of C + +, but C99 and C + + are incompatible

from:1190000000456199

Custom print macro, two pairs of parentheses, single parameter macro, specified parameter macro, variable parameter macros