C++ Socket庫數據分包與合包

在C++中，使用Socket庫進行數據通信時，可能需要將較大的數據分割成較小的數據包進行發送，以便在網絡中傳輸。同樣，接收端需要將這些數據包重新組合成原始數據。這個過程被稱為數據分包與合包。

以下是一個簡單的示例，展示了如何使用C++ Socket庫進行數據分包與合包：

#include <iostream>
#include <vector>
#include <cstring>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <unistd.h>

const int BUFFER_SIZE = 1024;

void sendData(int sockfd, const std::vector<char>& data) {
    int totalSent = 0;
    while (totalSent < data.size()) {
        int sent = send(sockfd, &data[totalSent], data.size() - totalSent, 0);
        if (sent == -1) {
            perror("send");
            break;
        }
        totalSent += sent;
    }
}

std::vector<char> receiveData(int sockfd, int bufferSize) {
    std::vector<char> buffer(bufferSize);
    int totalReceived = 0;
    while (totalReceived < bufferSize) {
        int received = recv(sockfd, &buffer[totalReceived], bufferSize - totalReceived, 0);
        if (received == -1) {
            perror("recv");
            break;
        } else if (received == 0) {
            break; // Connection closed
        }
        totalReceived += received;
    }
    return std::vector<char>(buffer.begin(), buffer.begin() + totalReceived);
}

int main() {
    int sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd == -1) {
        perror("socket");
        return 1;
    }

    struct sockaddr_in serverAddr;
    memset(&serverAddr, 0, sizeof(serverAddr));
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_port = htons(12345);
    if (inet_pton(AF_INET, "127.0.0.1", &serverAddr.sin_addr) <= 0) {
        perror("inet_pton");
        return 1;
    }

    if (connect(sockfd, (struct sockaddr*)&serverAddr, sizeof(serverAddr)) == -1) {
        perror("connect");
        return 1;
    }

    std::vector<char> data = {'H', 'e', 'l', 'l', 'o', ',', ' ', 'W', 'o', 'r', 'l', 'd', '!'};
    sendData(sockfd, data);

    std::vector<char> receivedData = receiveData(sockfd, BUFFER_SIZE);
    std::cout << "Received: " << std::string(receivedData.begin(), receivedData.end()) << std::endl;

    close(sockfd);
    return 0;
}

在這個示例中，我們使用了sendData函數將數據分包并發送，然后使用receiveData函數接收數據并將其合包。請注意，這個示例僅用于演示目的，實際應用中可能需要更復雜的錯誤處理和數據處理邏輯。