这个C++代码试图实现什么？

Question

我正在http://sourceforge.net/projects/dtmf/上学习DTMF代码.我遇到了一些我无法理解的C++代码:

template<int, int, int, int> class Types;
template <> class Types<5, 4, 2, 1>
{
public:
        typedef long int Int40;
        typedef unsigned long int Uint40;
        typedef int Int32;
        typedef unsigned int Uint32;
        typedef short int Int16;
        typedef unsigned short int Uint16;
        typedef char Int8;
        typedef unsigned char Uint8;
};
template <> class Types<8, 4, 2, 1>
{
public:
        typedef long int Int64;
        typedef unsigned long int Uint64;
        typedef int Int32;
        typedef unsigned int Uint32;
        typedef short int Int16;
        typedef unsigned short int Uint16;
        typedef char Int8;
        typedef unsigned char Uint8;
};
template <> class Types<4, 4, 2, 1>
{
public:
        typedef int Int32;
        typedef unsigned int Uint32;
        typedef short int Int16;
        typedef unsigned short int Uint16;
        typedef char Int8;
        typedef unsigned char Uint8;
};

// For 16bit chars
template <> class Types<2, 1, 1, 1>
{
public:
        typedef long int Int32;
        typedef unsigned long int Uint32;
        typedef short int Int16;
        typedef unsigned short int Uint16;
};

typedef Types<sizeof(long int), sizeof(int), sizeof(short int), sizeof(char)>::Int32     INT32;
typedef Types<sizeof(long int), sizeof(int), sizeof(short int), sizeof(char)>::Uint32    UINT32;
typedef Types<sizeof(long int), sizeof(int), sizeof(short int), sizeof(char)>::Int16     INT16;
typedef Types<sizeof(long int), sizeof(int), sizeof(short int), sizeof(char)>::Uint16    UINT16;

从那里,它们就像普通的原始类型一样使用:

static const INT16 tempCoeff[8];

我的直觉告诉我,所有这些东西都实现了某种跨平台的可移植性.我是对的,还是有更多的东西？

Answer 1

看起来他们正在重新发明stdint.h(我相信在某些/许多版本的MS编译器中不支持),它通过为基于调用的某些大小的整数类型提供一些可移植的机制sizeof.请注意,接受的第四个模板参数sizeof(char)完全没用,因为sizeof(char)始终为1.