如何使用C++编写高级嵌入式系统的各类功能

#include <iostream>
#include <thread>

void printHello() {
    std::cout << "Hello from thread!" << std::endl;
}

int main() {
    std::thread t(printHello);
    t.join(); // 等待子线程结束
    return 0;
}

#include <iostream>
#include <fstream>

int main() {
    std::ofstream ofs("data.txt"); // 创建写文件流
    if (ofs.is_open()) {
        ofs << "Hello, world!" << std::endl;
        ofs.close();
    }

    std::ifstream ifs("data.txt"); // 创建读文件流
    if (ifs.is_open()) {
        std::string line;
        while (std::getline(ifs, line)) {
            std::cout << line << std::endl;
        }
        ifs.close();
    }
    
    return 0;
}

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

int main() {
    int sockfd = socket(AF_INET, SOCK_STREAM, 0); // 创建socket
    if (sockfd == -1) {
        std::cerr << "Failed to create socket." << std::endl;
        return -1;
    }

    struct sockaddr_in addr;
    addr.sin_family = AF_INET;
    addr.sin_port = htons(8080);
    addr.sin_addr.s_addr = inet_addr("127.0.0.1");

    if (connect(sockfd, (struct sockaddr*)&addr, sizeof(addr)) < 0) { // 连接服务器
        std::cerr << "Failed to connect to server." << std::endl;
        return -1;
    }

    char buffer[1024] = {0};
    if (recv(sockfd, buffer, sizeof(buffer), 0) < 0) { // 接收数据
        std::cerr << "Failed to receive data." << std::endl;
        return -1;
    }

    std::cout << "Received: " << buffer << std::endl;

    close(sockfd); // 关闭socket

    return 0;
}

#include <iostream>
#include <sql.h>
#include <sqlext.h>

int main() {
    SQLHENV env;
    SQLHDBC dbc;
    SQLHSTMT stmt;
    SQLRETURN ret;

    SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &env);
    SQLSetEnvAttr(env, SQL_ATTR_ODBC_VERSION, (SQLPOINTER)SQL_OV_ODBC3, 0);
    SQLAllocHandle(SQL_HANDLE_DBC, env, &dbc);
    SQLDriverConnect(dbc, NULL, (SQLCHAR*)"DSN=mydsn;", SQL_NTS, NULL, 0, NULL, SQL_DRIVER_COMPLETE);

    SQLAllocHandle(SQL_HANDLE_STMT, dbc, &stmt);
    SQLExecDirect(stmt, (SQLCHAR*)"SELECT * FROM mytable", SQL_NTS);

    SQLCHAR col1[256];
    SQLLEN len1;
    while (SQLFetch(stmt) == SQL_SUCCESS) {
        SQLGetData(stmt, 1, SQL_C_CHAR, col1, sizeof(col1), &len1);
        std::cout << col1 << std::endl;
    }

    SQLFreeHandle(SQL_HANDLE_STMT, stmt);
    SQLDisconnect(dbc);
    SQLFreeHandle(SQL_HANDLE_DBC, dbc);
    SQLFreeHandle(SQL_HANDLE_ENV, env);

    return 0;
}