Question

如何重写以下宏以便它们实际遵循c ++约定？（在C ++中，我们更喜欢使用typedef，const和inline函数。
这是宏。

#define UBYTE unsigned char
#define ULONG unsigned long
#define FALSE 0
#define COMPRESS_MAX_COM 0x70000000
#define COMPRESS_MAX_ORG (1024-COMPRESS_OVERRUN)
#define MAX_RAW_GROUP (16*MAX_RAW_ITEM)
#define U(X) ((ULONG) X)

如何将上述宏更改为c ++约定？

Answer 1

对于类型，请使用typedef或using（C ++ 11）代替#define，然后使用const作为常量。这些函数可以在C ++ 11中定义为constexpr。

typedef unsigned char UBYTE;  // using UBYTE = unsigned char; // C++11
typedef unsigned long ULONG;
const unsigned int FALSE=0; // constexpr usigned int FALSE = 0; // C++11
const ULONG COMPRESS_MAX_COM=0x70000000;
const ULONG COMPRESS_MAX_ORG=(1024-COMPRESS_OVERRUN); // if COMPRESS_OVERRUN is const
const ULONG MAX_RAW_GROUP=(16*MAX_RAW_ITEM); // again if MAX_RAW_ITEM is a previously defined const
#define U(X) ((ULONG) X) // this can stay as it is

或

template <typename T>
ULONG U(const T& x)
{
    return static_cast<ULONG>(x);
}

所以U(some type T)将返回其T类型参数的强制转换为ULONG。

Answer 2

您应该考虑整数大小，尤其是在接口中使用这些定义时。

例如：

#include <stdint.h>
typedef uint8_t UBYTE;  // using UBYTE = unsigned char; // C++11
typedef uint32_t ULONG;
const uint32_t FALSE=0; // constexpr unsigned int FALSE = 0; // C++11

@vsoftco给出的其他定义很棒：

const ULONG COMPRESS_MAX_COM=0x70000000;
const ULONG COMPRESS_MAX_ORG=(1024-COMPRESS_OVERRUN); // if COMPRESS_OVERRUN is const
const ULONG MAX_RAW_GROUP=(16*MAX_RAW_ITEM); // again if MAX_RAW_ITEM is a previously defined const
#define U(X) ((ULONG) X) // this can stay as it is

宏的重写遵循c ++约定

2 个答案: