VC++ 中实现进制2进制，10进制，16进制的相互转换

下面是一个图例表示转换过程使用的函数

BinToDec CString::Format
2 --------------------------> 10 ---------------------------> 16
2 <-------------------------- 10 <--------------------------- 16
DecToBin strtoul

1. 2 进制 -----> 10 进制
CString BinToDec(CString strBin)
{
CString strDec;
long nDec = 0, nLen;
int i, j, k;

nLen = strBin.GetLength();
for (i=0; i<nLen; i++)
{
if ( strBin[nLen-i-1] == '0' )
continue;
else
{
k = 1;
for(j=0; j<i; j++)
k = k * 2;
nDec += k;
}
}

strDec.Format("%ld", nDec);

return strDec;
}

2. 10 进制 -----> 2 进制
CString DecToBin(CString strDec)
{
int nDec = atoi(strDec);
int nYushu, nShang;
CString strBin = _T(""), strTemp;
TCHAR buf[2];
BOOL bContinue = TRUE;

while ( bContinue )
{
nYushu = nDec % 2;
nShang = nDec / 2;
sprintf(buf, "%d", nYushu);
strTemp = strBin;
strBin.Format("%s%s", buf, strTemp);
nDec = nShang;
if ( nShang == 0 )
bContinue = FALSE;
}

int nTemp = strBin.GetLength()%4;
switch(nTemp)
{
case 1:
strTemp.Format(_T("000%s"), strBin);
strBin = strTemp;
break;
case 2:
strTemp.Format(_T("00%s"), strBin);
strBin = strTemp;
break;
case 3:
strTemp.Format(_T("0%s"), strBin);
strBin = strTemp;
break;
default:
break;
}

return strBin;
}

3. 2进制 -----> 16进制
2进制先转换为10进制，再转换为16进制

CString strDec, strBin, strHex;
strBin = _T("1110");
strDec = BinToDec(strBin);
int nDec;
nDec = atol(strDec);
strHex.Format(_T("%x"), nDec);

4. 10 进制 -----> 16 进制
int nDec = 10;
CString str;
str.Fomat(_T("%x"), nDec);

5. 16 进制 -----> 10 进制
CString strDec, strHex;
strHex = _T("af");
DWORD dwHex = strtoul(strHex, NULL, 16);
strDec.Format(_T("%ld"), dwHex);

6. 16 进制 -----> 2 进制
16进制先转换为10进制，再转换为2进制

CString strDec, strBin, strHex;
strHex = _T("af");
DWORD dwHex = strtoul(strHex, NULL, 16);
strDec.Format(_T("%ld"), dwHex);
strBin = DecToBin(strDec);

只是简单写了一下，没有考虑效率问题。

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