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);