关于C++数据类型转换和格式化输出的问题

void Test()

{

//原则

//字节相同，只作二进制拷贝

//2字节->4字节，根据符号性先将2字节的数据转换成对应的4字节

//4字节->2字节，直接拷贝低位

int i = 0;

{

//INT16 -> UINT16

//UINT16 -> UINT16

}

{

//INT32 -> UINT32

INT32 n1 = 0xffffffff;

UINT32 u1 = n1;//0xffffffff

++i;

}

{

//UINT32 -> INT32

UINT32 u1 = 0xffffffff;

INT32 n1 = u1;//0xffffffff

++i;

}

{

//INT16 -> INT32

INT16 n1 = 0xffff;

INT32 n2 = n1; //0xffffffff, 2字节扩展到4字节，符号保持不变

++i;

}

{

//INT16 -> UINT32

INT16 n1 = 0xffff;

UINT32 u1 = n1; //0xffffffff, INT16->INT32->UINT32

u1 = (UINT32)(n1&0x0000ffff); //0xffff

n1 = 0x1;

u1 = n1;//0x1

++i;

}

{

//UINT16 -> UINT32

UINT16 u1 = 0xffff;

UINT32 u2 = u1;//0x0000ffff，高位补0

++i;

}

{

//UINT16 -> INT32

UINT16 u1 = 0xffff;

INT32 n1 = u1;//0xffff, UINT16 -> UINT32 -> INT32

++i;

}

{

//INT32 -> INT16

INT32 n1 = 0xf0001000;

INT16 n2 = n1; //0x1000,直接截断，取低2字节

//INT32 -> UINT16

n1 = 0xf1234567;

UINT16 u1 = n1; //0x4567,直接截断，取低2字节

++i;

}

{

//UINT32 -> INT16

UINT32 u1 = 0xf123f456;

INT16 n1 = u1; //0x4567,直接截断，取低2字节

//UINT32 -> UINT16

UINT16 u2 = u1; //0x4567,直接截断，取低2字节

++i;

}

}

void Test2()

{

//     UINT64 u1 = 0x1200003456000078;

//     UINT32 u2= UINT32(u1&(UINT64)0x00000000ffffffff);

//     UINT32 u3= UINT32(u1>>32);

//     printf("UINT64 is: %0.16llx\n", u1);

//     printf("UINT32 low: %0.8x\n", u2);

//     printf("UINT32 hi: %0.8x\n", u3);

//%d需要一个INT32（如果不足4字节，转成4字节），转成INT32,而不关心变量本身的数据类型

//%u需要一个UIN32（如果不足4字节，转成4字节），转成UINT32,而不关心变量本身的数据类型

{

//%d/%u + INT32

INT32 n1 = 0xffffffff;

TEA_LOG(LOG_DEBUG, _T("INT32 %d, %u"), n1, n1);

//INT32 -1, 4294967295

}

{

//%d/%u + UINT32

UINT32 u1 = 0xffffffff;

TEA_LOG(LOG_DEBUG, _T("UINT32 %d, %u"), u1, u1);

//UINT32 -1, 4294967295

}

{

//%d/%u + INT16

INT16 n1 = 0xffff;

TEA_LOG(LOG_DEBUG, _T("INT16 %d, %u"), n1, n1);

//INT16 -1, 4294967295

//INT16 -> INT32 -> UINT32

}

{

//%d/%u + UINT16

UINT16 u1 = 0xffffffff;

TEA_LOG(LOG_DEBUG, _T("UINT16 %d, %u"), u1, u1);

//UINT16 65535, 65535

}

}