post数据的时候“+”号被替换成空格了。。。

调试的时候可以看到post的数据里面是有“+”号的，但是用截包工具（HttpAnalyzer）截到的数据里面“+”全部被替换成空格了这是什么问题呢。。我post数据的函数代码如下：
BOOL PostData(const char *szUrl,const char *szContent,CString &strResult)
{
    static const char *hdrs = "Content-Type: application/x-www-form-urlencoded"; 
    static const char *acpt = "acpt: */*"; 
    BOOL bRet = TRUE;
    strResult="";
    HINTERNET hInternet = InternetOpen("PostData",INTERNET_OPEN_TYPE_PRECONFIG,NULL,NULL,0);
    if(hInternet!=NULL)
    {
        URL_COMPONENTS UrlComponents;
        memset(&UrlComponents,0,sizeof(UrlComponents));
        UrlComponents.dwStructSize=sizeof(UrlComponents);
        UrlComponents.dwHostNameLength=64;
        char szHostName[64];
        UrlComponents.lpszHostName=szHostName;
        UrlComponents.dwUrlPathLength=256;    // length of URL-path
        InternetCrackUrl(szUrl,0,0,&UrlComponents);
        UrlComponents.lpszHostName[UrlComponents.dwHostNameLength]=0;
        HINTERNET hConnect = InternetConnect(hInternet, UrlComponents.lpszHostName, UrlComponents.nPort, NULL, NULL, INTERNET_SERVICE_HTTP, 0, 1); 
        if(hConnect!=NULL)
        {
            HINTERNET hRequest = HttpOpenRequest(hConnect, "POST", UrlComponents.lpszUrlPath, NULL, NULL, &acpt, 0, 1); 
            if(hRequest!=NULL)
            {
HttpSendRequest(hRequest, hdrs, strlen(hdrs), (void *)szContent,strlen(szContent));  
                char pBuf[4096];
                DWORD dwMaxDataLength=4096;
                DWORD dwReadDataLength=0;
                DWORD dwReadLength;
                memset(pBuf,0,4096);
                while(InternetReadFile(hRequest,pBuf,dwMaxDataLength,&dwReadLength)&&dwReadLength!=0)
                {
                    strResult+=pBuf;
                    memset(pBuf,0,4096);
                }
                InternetCloseHandle(hRequest);
            }
            else
            {
                bRet = FALSE;
            }
            InternetCloseHandle(hConnect);
        }
        else
        {
            bRet = FALSE;
        }
        InternetCloseHandle(hInternet);
    }
    return bRet;
}