#include <stdio.h>

int main() {
    printf("Hello, World!\n");
    return 0;
}

#include <stdio.h>

int main() {
    int num;
    printf("请输入一个数字：");
    scanf("%d", &num);

    if (num > 0) {
        printf("这个数字是正数。\n");
    } else {
        printf("这个数字是非正数。\n");
    }

    return 0;
}

#include <stdio.h>

void greet() {
    printf("Hello!\n");
}

int main() {
    greet();
    return 0;
}

#include <stdio.h>

void changeValue(int a) {
    a = 10; // 只改变局部变量，不影响实际参数
}

void changeValueByReference(int *a) {
    *a = 10; // 改变实际参数
}

int main() {
    int x = 5;
    changeValue(x);
    printf("x = %d\n", x); // 输出：x = 5

    changeValueByReference(&x);
    printf("x = %d\n", x); // 输出：x = 10

    return 0;
}

#include <stdio.h>

int main() {
    int arr[5] = {1, 2, 3, 4, 5};
    for (int i = 0; i < 5; i++) {
        printf("%d ", arr[i]);
    }
    printf("\n");
    return 0;
}

#include <stdio.h>

struct Student {
    char name[50];
    int age;
};

int main() {
    struct Student s1 = {"Alice", 20};
    printf("Name: %s, Age: %d\n", s1.name, s1.age);
    return 0;
}

#include <stdio.h>

int main() {
    int arr[3] = {10, 20, 30};
    int *p = arr; // p指向数组的首元素
    
    for (int i = 0; i < 3; i++) {
        printf("%d ", *(p + i)); // 访问数组元素
    }
    printf("\n");
    return 0;
}

#include <stdio.h>

int main() {
    FILE *file = fopen("example.txt", "w"); // 打开文件进行写入
    if (file == NULL) {
        printf("无法打开文件！\n");
        return 1;
    }

    fprintf(file, "Hello, file!\n"); // 写入内容
    fclose(file); // 关闭文件
    printf("文件已成功关闭。\n");
    
    return 0;
}

#include <stdio.h>
#include <stdlib.h>
// 假设的GPIO库
#include "gpio.h"

// 定义LED连接的GPIO引脚
#define LED_PIN 21

int main() {
    // 初始化GPIO
    gpio_init(LED_PIN, GPIO_OUT);
    
    // 点亮LED
    gpio_write(LED_PIN, 1);
    printf("LED is ON\n");
    
    // 暂停一段时间
    sleep(1);
    
    // 熄灭LED
    gpio_write(LED_PIN, 0);
    printf("LED is OFF\n");
    
    // 清理GPIO
    gpio_cleanup(LED_PIN);
    
    return 0;
}

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <termios.h>

// 串口设备
#define SERIAL_PORT "/dev/serial0"

void setup_serial(int fd) {
    struct termios options;
    tcgetattr(fd, &options);
    cfsetispeed(&options, B9600);
    cfsetospeed(&options, B9600);
    options.c_cflag |= (CLOCAL | CREAD);
    options.c_cflag &= ~PARENB; // 无奇偶校验
    tcsetattr(fd, TCSANOW, &options);
}

int main() {
    int fd = open(SERIAL_PORT, O_RDWR | O_NOCTTY);
    if (fd == -1) {
        perror("Unable to open serial port");
        return -1;
    }
    
    setup_serial(fd);
    
    // 发送数据
    const char *msg = "Hello UART!";
    write(fd, msg, strlen(msg));
    
    // 接收数据
    char buffer[256];
    int n = read(fd, buffer, sizeof(buffer));
    buffer[n] = '\0'; // 确保字符串正确结束
    printf("Received: %s\n", buffer);
    
    // 关闭串口
    close(fd);
    
    return 0;
}

#include <stdio.h>
#include <wiringPi.h>
#include <wiringPiSPI.h>

#define SPI_CHANNEL 0 // SPI通道
#define SPEED 500000  // 波特率

int main() {
    wiringPiSetup(); // 初始化WiringPi库
    wiringPiSPISetup(SPI_CHANNEL, SPEED);
    
    uint8_t data[] = {0x01, 0x02, 0x03}; // 要发送的数据
    uint8_t response[3];
    
    // 发送数据
    wiringPiSPIDataRW(SPI_CHANNEL, data, sizeof(data));
    
    // 假设需要读取响应
    wiringPiSPIDataRW(SPI_CHANNEL, response, sizeof(response));
    
    printf("Received: %02X %02X %02X\n", response[0], response[1], response[2]);
    
    return 0;
}

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <linux/i2c-dev.h>
#include <sys/ioctl.h>

#define I2C_DEVICE "/dev/i2c-1"
#define I2C_ADDRESS 0x48 // 示例I2C设备地址

int main() {
    int file = open(I2C_DEVICE, O_RDWR);
    if (file < 0) {
        perror("Failed to open I2C device");
        return -1;
    }

    if (ioctl(file, I2C_SLAVE, I2C_ADDRESS) < 0) {
        perror("Failed to connect to I2C device");
        return -1;
    }

    char writeBuffer[2] = {0x00, 0x01}; // 要写入的数据
    if (write(file, writeBuffer, 2) != 2) {
        perror("Failed to write to the I2C bus");
    }

    char readBuffer[1];
    if (read(file, readBuffer, 1) != 1) {
        perror("Failed to read from the I2C bus");
    }
    
    printf("Read from I2C device: %02X\n", readBuffer[0]);

    close(file);
    return 0;
}