c语言#/##的使用

#include <stdio.h>

typedef  struct struAVClass{
    const char* class_name;
    const char* (*item_name)(void* ctx);
    const char* option;
}AVClass;


#define DEFINE_WRITER_CLASS(name)                   \
static const char *name##_get_name(void *ctx)       \
{                                                   \
    return #name ;                                  \
}                                                   \
static const AVClass name##_class = {               \
    .class_name = #name,                            \
    .item_name  = name##_get_name,                  \
    .option     = "name##_options"                  \
}

static const char* test_options = "test_options";
static const char* west_options = "west_options";
DEFINE_WRITER_CLASS(test);
DEFINE_WRITER_CLASS(west);

int main()
{
    printf("class_name=%s, item_name=%s, option=%s
", test_class.class_name, test_class.item_name(NULL), test_class.option);
    printf("class_name=%s, item_name=%s, option=%s
", west_class.class_name, west_class.item_name(NULL), west_class.option);
    return 0;
}