字符串压缩(面试准备)

我需要压缩字符串。可以假设字符串中的每个字符出现不超过255次。我需要返回压缩字符串和它的长度。在过去的两年里，我一直在学习c#，而忘记了c++。我很高兴听到你对代码、算法和c++编程实践的评论

// StringCompressor.h
class StringCompressor
{
public:
    StringCompressor();
    ~StringCompressor();
    unsigned long Compress(string str, string* strCompressedPtr);
    string DeCompress(string strCompressed);
private:
    string m_StrCompressed;
    static const char c_MaxLen;
};
// StringCompressor.cpp
#include "StringCompressor.h"
const char StringCompressor::c_MaxLen = 255;
StringCompressor::StringCompressor()
{
}

StringCompressor::~StringCompressor()
{
}
unsigned long StringCompressor::Compress(string str, string* strCompressedPtr)
{
    if (str.empty())
    {
        return 0;
    }
    char currentChar = str[0];
    char count = 1;
    for (string::iterator it = str.begin() + 1; it != str.end(); ++it)
    {
        if (*it == currentChar)
        {
            count++;
            if (count == c_MaxLen)
            {
                return -1;
            }
        }
        else
        {
            m_StrCompressed+=currentChar;
            m_StrCompressed+=count;
            currentChar = *it;
            count = 1;
        }
    }
    m_StrCompressed += currentChar;
    m_StrCompressed += count;
    *strCompressedPtr = m_StrCompressed;
    return m_StrCompressed.length();
}
string StringCompressor::DeCompress(string strCompressed)
{
    string res;
    if (strCompressed.length() % 2 != 0)
    {
        return res;
    }
    for (string::iterator it = strCompressed.begin(); it != strCompressed.end(); it+=2)
    {
        char dup = *(it + 1);
        res += string(dup, *it);
    }
    return res;
}