C++ 客戶端套接字只接收消息的首字母

Question

在過去的幾天里，我一直被困在一個問題上。 我需要在 C++ 中設計一個音樂流媒體應用程序。 但是，我發現很難發送從目錄中讀取文件時獲得的文件名。 文件名是“sample.wav”和“sample1.wav”，但客戶端每次都會收到 output 只是字母 S。 雖然如果我手動發送從服務器分配給變量的字符串消息，客戶端會收到它只是找到。 你能為我指出正確的方向嗎？

提前致謝。

服務器端

        sockaddr_in hint;
        hint.sin_family = AF_INET;
        hint.sin_port = htons(54000);

        hint.sin_addr.S_un.S_addr = INADDR_ANY;
        // for local ip: inet_pton

        bind(listening, (sockaddr*)&hint, sizeof(hint));

        // max number of open connections (SOMAXCONN)
        listen(listening, SOMAXCONN);

        // waiting for connection
        sockaddr_in client;
        int clientSize = sizeof(client);

        SOCKET clientSocket = accept(listening, (sockaddr*)&client, &clientSize);

        SOCKET* client_ptr = &clientSocket;
        char host[NI_MAXHOST];
        // client's remote name

        char service[NI_MAXSERV];
        // the port on which the client connects

        ZeroMemory(host, NI_MAXHOST);
        //ZeroMemory(service, NI_MAXHOST);
        // cleaning memory

        sockList.push_back(&clientSocket);

        if (getnameinfo((sockaddr*)&client, sizeof(client), host, NI_MAXHOST, service, NI_MAXSERV, 0) == 0)
        {
            for (int i = 0; i < 2; i++) {
                int postList = send(clientSocket, mainList.GetSongName(i).c_str(), mainList.GetSongName(i).size() + 1,0);
            }
        }
        else {

            inet_ntop(AF_INET, &client.sin_addr, host, NI_MAXHOST);
            cout << host << " connected on port " << ntohs(client.sin_port) << endl;
        }

        closesocket(listening);
 }

客戶端：

string ipAddress = "127.0.0.1";
int port = 54000;

WSAData data;
WORD ver = MAKEWORD(2, 2);

int wsResult = WSAStartup(ver, &data);

if (wsResult != 0) {
    cerr << "Can't start Winsock, Err #:" << wsResult << endl;
    return 0;
}

SOCKET sock = socket(AF_INET, SOCK_STREAM, 0);

if (sock == INVALID_SOCKET) {
    cerr << "Can't create socket. Err #:" << WSAGetLastError << endl;
    return 0;
}

sockaddr_in hint;
hint.sin_family = AF_INET;
hint.sin_port = htons(port);

inet_pton(AF_INET, ipAddress.c_str(), &hint.sin_addr);

//hint.sin_addr.S_un.S_addr = INADDR_ANY;

int connResult = connect(sock, (sockaddr*)&hint, sizeof(hint));

bind(sock, (sockaddr*)&hint, sizeof(hint));

if (connResult == SOCKET_ERROR) {
    cerr << "Can't connect to Server, Err #:" << WSAGetLastError() << endl;
    closesocket(sock);
    WSACleanup();
}

char buffer[4096];
string userInput;

ZeroMemory(buffer, 4096);

int msglen;
int numbytes = 0;

int welcomemsg = recv(sock, buffer, sizeof(buffer), 0);

cout << sizeof(buffer) << endl;
cout << "Server >>" << string(buffer, 0, welcomemsg) << endl;

do {
     welcomemsg = recv(sock, buffer, 4096, 0);

    if (welcomemsg > 0) {
        cout << "Server >>" << string(buffer, 0, welcomemsg) << endl;
    }
    else {
        cerr << "Client disconnected" << endl;
    }
} while (welcomemsg > 0);

songList object 構造函數：

wchar_t* w_Path = (wchar_t*)malloc(strlen(filePath) * sizeof(wchar_t));

mbstowcs(w_Path, filePath, strlen(filePath) + 1);

HANDLE hFind;
WIN32_FIND_DATA data;

LPCWSTR m_Path = w_Path;

memset(&data, 0, sizeof(WIN32_FIND_DATA));

hFind = FindFirstFile(m_Path, &data);

if (hFind != INVALID_HANDLE_VALUE) {
    int i = 0;

    do {
        printf("\n %S", data.cFileName);
        songNames[i] = (char*)data.cFileName;
        i++;
    } while (FindNextFile(hFind, &data));
    FindClose(hFind);
}
else {
    cout << "No songs found in directory" << endl;
}

Answer 1

您對字符串構造函數的使用不正確

    cout << "Server >>" << string(buffer, 0, welcomemsg) << endl;

應該

    cout << "Server >>" << string(buffer, welcomemsg) << endl;

Answer 2

問題是你在 Unicode 模式下工作，結構WIN32_FIND_DATA是typedef d to WIN32_FIND_DATAW ，所以songNames[i] = (char*)data.cFileName; 將wchar_t字符串重新解釋為單字節字符。

被視為多字節，一個whar_t字符的字符串看起來像一個以空字符結尾的 1 個字符的字符串。

作為一個快速和骯臟的修復，將您的服務器項目模式更改為多字節（注意 - 代碼中可能存在更多錯誤，因此可能需要更多修復才能使其正常工作）。

但更好的是，繼續使用 Unicode 模式並調整代碼以使用wchar_t字符而不是char 。 這意味着將char buffer[]更改為wchar_t buffer[]並在必要時調整大小值。