上面一段是原来的代码，因为这个buffstr字符串不是定长的，所以改了下。但有错误提示！怎么正确的修改?
这句代码：n = (USHORT)(buf + i * 2);//这里会有警告 C26451 算术溢出: 使用 4 字节值上的运算符 * ，然后将结果转换到 8 字节值。在调用运算符 * 之前将值强制转换为宽类型可避免溢出(io.2)。
原代码：
BYTE Buf[] = { 0x45,0x00,0x01,0x65,0x01,0x00,0x00,0x00,0x80,0x11,0x31,0x39,0x32,0x2E,
0x31,0x36,0x38,0x2E,0x33,0x31,0x2E,0x31,0x38,0x38,0xFF,0xFF,0xFF,0xFF };
const int cbBuf = sizeof(Buf);
const int iCount = cbBuf / 2;
int iCheckSum = 0, n;
for (int i = 0; i < iCount; ++i)
{
n = *(USHORT*)(Buf + i * 2);
iCheckSum += n;
}
if ((iCheckSum >> 16) > 0)
{
iCheckSum = (iCheckSum >> 16) + (iCheckSum & 65535);
iCheckSum += iCheckSum >> 16;
}
BYTE byResult[2];
iCheckSum = ~iCheckSum;
memcpy(byResult, &iCheckSum, 2);
cout << (int)byResult[0] << "," << (int)byResult[1];
修改的代码：
void HexStrToByte(const char* source, unsigned char* dest, int sourceLen)
{
short i;
unsigned char highByte, lowByte;
for (i = 0; i < sourceLen; i += 2)
{
highByte = toupper(source[i]);
lowByte = toupper(source[i + 1]);
if (highByte > 0x39)
highByte -= 0x37;
else
highByte -= 0x30;
if (lowByte > 0x39)
lowByte -= 0x37;
else
lowByte -= 0x30;
dest[i / 2] = (highByte << 4) | lowByte;
}
return;
}
string buffstr = "450001650100000080113139322E3136382E33312E313838FFFFFFFF";
const char* strp = buffstr.c_str();
byte* buf = new byte[buffstr.length() / 2];
HexStrToByte(strp, buf, buffstr.length() / 2);
//因为这个buffstr字符串不是定长的，所以以上要改。
const int cbBuf = buffstr.length() / 2;
const int iCount = cbBuf / 2;
int iCheckSum = 0, n;
for (int i = 0; i < iCount; ++i)
{
n = *(USHORT*)(buf + i * 2);//这里会提示算数溢出，什么4字节
iCheckSum += n;
}
if ((iCheckSum >> 16) > 0)
{
iCheckSum = (iCheckSum >> 16) + (iCheckSum & 65535);
iCheckSum += iCheckSum >> 16;
}
BYTE byResult[2];
iCheckSum = ~iCheckSum;
memcpy(byResult, &iCheckSum, 2);
cout << (int)byResult[0] << "," << (int)byResult[1];
delete[] buf;
buf = NULL;
正确的修改应该是：
string buffstr = "450001650100000080113139322E3136382E33312E313838FFFFFFFF";
const char* strp = buffstr.c_str();
byte* buf = new byte[buffstr.length() / 2];
HexStrToByte(strp, buf, buffstr.length() / 2);
const int cbBuf = buffstr.length() / 2;
const int iCount = cbBuf / 2;
int iCheckSum = 0;
for (int i = 0; i < iCount; ++i)
{
USHORT n = *(USHORT*)(buf + i * 2);
iCheckSum += n;
}
if ((iCheckSum >> 16) > 0)
{
iCheckSum = (iCheckSum >> 16) + (iCheckSum & 65535);
iCheckSum += iCheckSum >> 16;
}
BYTE byResult[2];
iCheckSum = ~iCheckSum;
memcpy(byResult, &iCheckSum, 2);
cout << (int)byResult[0] << "," << (int)byResult[1];
delete[] buf;
buf = NULL;
这里将变量n的类型修改为USHORT，同时在循环内计算时进行类型转换。另外，将buf的定义修改为byte*类型，并将其内存分配放在循环外面，同时在循环结束后释放内存。
不知道你这个问题是否已经解决, 如果还没有解决的话: