C++ 将十六进制字符串转换为二进制字符串

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前言

一种简单的方法将十六进制字符串转为二进制字符串，不限制十六进制的字节数。

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一. 源代码

传入的十六进制字符串需要转换为大写！(%X, toupper())。

string GetBinaryStringFromHexString (string strHex)
{
    string sReturn = "";
    unsigned int len = strHex.length();
    for (unsigned int i = 0; i<len; i++)
    {
        switch ( strHex[i])
        {
            case '0': sReturn.append ("0000"); break;
            case '1': sReturn.append ("0001"); break;
            case '2': sReturn.append ("0010"); break;
            case '3': sReturn.append ("0011"); break;
            case '4': sReturn.append ("0100"); break;
            case '5': sReturn.append ("0101"); break;
            case '6': sReturn.append ("0110"); break;
            case '7': sReturn.append ("0111"); break;
            case '8': sReturn.append ("1000"); break;
            case '9': sReturn.append ("1001"); break;
            case 'A': sReturn.append ("1010"); break;
            case 'B': sReturn.append ("1011"); break;
            case 'C': sReturn.append ("1100"); break;
            case 'D': sReturn.append ("1101"); break;
            case 'E': sReturn.append ("1110"); break;
            case 'F': sReturn.append ("1111"); break;
        }
    }
    return sReturn;
}