面试题九宫格输入法，数字和字符串转换

#include <iostream>
#include "string.h"
#include <map>
using namespace std;


class CTransfer
{
public:
    CTransfer();
    ~CTransfer();

    void statToTrans(const string src, string& outString);
private:
    string praseStr(const string srcStr, const char filter);
    bool  getChar(const string str, string& outC);
private:
    map<char, string> charMap;
};

CTransfer::CTransfer()
{
    charMap.insert(make_pair<char, string>('2', "ABC"));
    charMap.insert(make_pair<char, string>('3', "DEF"));
    charMap.insert(make_pair<char, string>('4', "GHI"));
    charMap.insert(make_pair<char, string>('5', "JKL"));
    charMap.insert(make_pair<char, string>('6', "MNO"));
    charMap.insert(make_pair<char, string>('7', "PQRS"));
    charMap.insert(make_pair<char, string>('8', "TUV"));
    charMap.insert(make_pair<char, string>('9', "WXYZ"));
}

CTransfer::~CTransfer()
{
    charMap.clear();
}

void CTransfer::statToTrans(const string src, string& outString)
{
    string srcStr = src;
    while (1)
    {
        size_t pos = srcStr.find(' ');
        if (pos != srcStr.npos)
        {
            string outChar;
            string subStr = srcStr.substr(0, pos);
            if (getChar(subStr, outChar))
            {
                outString.append(outChar);
            }
            srcStr = srcStr.substr(pos + 1);
        }
        else
        {
            string outChar;
            if (getChar(srcStr, outChar))
            {
                outString.append(outChar);
            }

            break;
        }
    }
        
}

bool CTransfer::getChar(const string str, string& outC)
{
    for (int i = 1; i < str.length(); i++)
    {
        if (str[0] != str[i])
        {
            return false;
        }
    }

    map<char, string>::iterator itor = charMap.find(str[0]);
    if (itor != charMap.end())
    {
        if (str[0] == '7' || str[0] == '9')
        {
            int index = (str.length() - 1) % 4;
            outC = (itor->second)[index];
        }
        else
        {
            int index = (str.length() - 1) % 3;
            outC = (itor->second)[index];
        }

        return true;
    }

    return false;
}

string CTransfer::praseStr(const string srcStr, const char filter)
{
    string retStr;
    retStr.clear();
    size_t  pos = srcStr.find(filter);
    if (pos != srcStr.npos)
    {
        retStr = srcStr.substr(0, pos);
    }
    else
    {
        retStr = "";
    }

    return retStr;
}

int main()
{
    string str = "22 33 44 55       9 88 ";
    string outstr;
    CTransfer obj;
    obj.statToTrans(str, outstr);

    printf("%s\n", outstr.c_str());
    system("pause");
    return 0;
}