C++ Socket库数据分包与合包

在C++中，使用Socket库进行数据通信时，可能需要将较大的数据分割成较小的数据包进行发送，以便在网络中传输。同样，接收端需要将这些数据包重新组合成原始数据。这个过程被称为数据分包与合包。

以下是一个简单的示例，展示了如何使用C++ Socket库进行数据分包与合包：

#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;
}

在这个示例中，我们使用了sendData函数将数据分包并发送，然后使用receiveData函数接收数据并将其合包。请注意，这个示例仅用于演示目的，实际应用中可能需要更复杂的错误处理和数据处理逻辑。