notices for complex macro definition in C

notices for complex macro definition in C

1. space is prohibitted after the backslash(\) 

otherwise the below build error will be prompted:

backslash and newline separated by space

 

2. be noticed to -> of structure pointer in macro definition and & in macro reference

#define CUSTOM_PRINT(pt_examp_struct)      \
do                       \
{                        \
printf("age: %d\n", pt_examp_struct->ui1_age);      \
printf("name: %d\n", pt_examp_struct->ac_name);      \
} while(0)

reference:
T_EXAMP_STRUCT t_examp_struct = {26, "hello world!"}
CUSTOM_PRINT(&t_examp_struct);

build error will be prompted when compiling.
reason: expanding the macro:
printf("age: %d\n", &t_examp_struct->ui1_age);

t_examp_struct is a structure. -> operator has the higher priority than &. t_examp_struct->ui1_age is wrong.

correct it:
#define CUSTOM_PRINT(pt_examp_struct)          \
do                              \
{                              \
T_EXAMP_STRUCT *pt_examp_struct = &t_examp_struct;    \
printf("age: %d\n", pt_examp_struct->ui1_age);        \
printf("name: %d\n", pt_examp_struct->ac_name);        \
} while(0)

reference:
CUSTOM_PRINT(t_examp_struct);

 

posted @ 2017-07-04 16:01  aspirs  阅读(265)  评论(0编辑  收藏  举报