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在 SO 上找到了这个非常有用的 Q/A:有没有办法在 C 中循环使用具有不同类型元素的结构?

但是由于我对整个 X-Macro 的东西还很陌生,所以我想知道,是否以及如何将这个示例改编为带有数组的结构 - 如下所示:

typedef struct
{    
    uint8    Addr1[SIZEOF_ADDR];
    uint8    Addr2[SIZEOF_ADDR];
    uint8    Addr3[SIZEOF_ADDR];
} TEST;

这是要适应的:

//--- first describe the structure, the fields, their types and how to print them
#define X_FIELDS \
    X(int, field1, "%d") \
    X(int, field2, "%d") \
    X(char, field3, "%c") \
    X(char *, field4, "%s")

//--- define the structure, the X macro will be expanded once per field
typedef struct {
#define X(type, name, format) type name;
    X_FIELDS
#undef X
} mystruct;

我的出发点是这样的,但我很确定,格式必须是别的东西,或者必须被替换:

#define X_FIELDS \
    X(uint8, Addr1, "%02X") \
    X(uint8, Addr2, "%02X") \    
    X(uint8, Addr3, "%02X")

地址类似于 {0x10,0x12,0x0A} - 大小相同。

编辑:

这是我当前如何使用这个结构的一个例子,没有 x 宏:

TEST test =  {{0x16,0xA4,0x3},
              {0x16,0xA4,0x2},
              {0x16,0xA4,0x1}};

printf("%02X",test.addr1[i]);
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1 回答 1

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你有一个合理的开始...

#include <stdio.h>
typedef unsigned char uint8;
enum { SIZEOF_ADDR = 3 };

#define X_FIELDS \
    X(uint8, Addr1, "0x%02X") \
    X(uint8, Addr2, "0x%02X") \
    X(uint8, Addr3, "0x%02X")

//--- define the structure, the X macro will be expanded once per field
typedef struct {
#define X(type, name, format) type name[SIZEOF_ADDR];
    X_FIELDS
#undef X
} TEST;

extern void iterate1(TEST *test);
extern void iterate2(TEST *test);

//--- Print the values
void iterate1(TEST *test)
{
     const char *pad;
//--- "iterate" over all the fields of the structure
#define X(type, name, format) \
         printf("%s is ", #name); \
         pad = "{"; \
         for (size_t i = 0; i < sizeof(test->name); i++) \
         { \
              printf("%s" format, pad, test->name[i]); \
              pad = ","; \
         } \
         printf("}\n");
X_FIELDS
#undef X
}

// Alternatively, define a function `print_addr()`
static void print_addr(const char *format, const uint8 *addr, size_t addrsize)
{
    char pad = '{';
    for (size_t i = 0; i < addrsize; i++)
    {
        putchar(pad);
        printf(format, addr[i]);
        pad = ',';
    }
    putchar('}');
}

//--- Print the values using print_addr()
void iterate2(TEST *test)
{
    //--- "iterate" over all the fields of the structure
#define X(type, name, format) \
    printf("%s is ", #name); \
    print_addr(format, test->name, sizeof(test->name)); \
    printf("\n");
    X_FIELDS
#undef X
}

(此代码被视为单个文件,已知可以在 Mac OS X 10.7.5 上的 GCC 4.7.1 下干净地编译。)

于 2012-11-26T09:34:37.673 回答