#include<stdio.h> int main() { float h = 100; int n = 0; int i = 0; float ret = 0; float sum = 0; scanf("%d", &n); for (i = 0; i < n; i++) { sum += h; ret = h / 2; h = ret; } printf("the total of road is %f\n",sum); printf("the tenth is %f meter\n",ret); return 0; }

这段代码是一个简单的求高度为100米的球从100米高度自由落体，第n次反弹后总共走过的路程和第n次反弹的高度的程序。通过输入n的值，程序利用for循环进行n次反弹，每次反弹高度除以2，最后累加每次反弹的高度，得到总共走过的路程。同时，第n次反弹的高度也被计算出来，存储在变量ret中，最后输出总共走过的路程和第n次反弹的高度。

相关问题

写一个基于gec6818和ds18b20的温度检测代码

以下是基于gec6818和ds18b20的温度检测代码，需要先在终端执行一些命令安装相关工具：

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

#define I2C_DEV "/dev/i2c-1" // i2c设备文件路径
#define DS18B20_ADDR 0x48 // ds18b20设备地址

int main()
{
    int fd, ret;
    char buf[2];
    uint8_t data[2];
    float temperature;

    fd = open(I2C_DEV, O_RDWR); // 打开i2c设备文件
    if (fd < 0) {
        perror("open i2c device failed");
        exit(1);
    }

    ret = ioctl(fd, I2C_SLAVE, DS18B20_ADDR); // 设置i2c从设备地址
    if (ret < 0) {
        perror("ioctl I2C_SLAVE failed");
        exit(1);
    }

    buf[0] = 0xAC; // 发送读取温度的命令
    buf[1] = 0x80; // 设置温度分辨率为12bit
    ret = write(fd, buf, 2);
    if (ret < 0) {
        perror("write failed");
        exit(1);
    }

    usleep(1000); // 等待转换完成

    ret = read(fd, data, 2); // 读取温度数据
    if (ret < 0) {
        perror("read failed");
        exit(1);
    }

    temperature = (data[0] << 4) | (data[1] >> 4); // 计算温度值
    temperature = temperature * 0.0625;

    printf("Temperature: %.2f°C\n", temperature);

    close(fd); // 关闭i2c设备文件

    return 0;
}

编译运行：

$ gcc -o temp_detect temp_detect.c
$ ./temp_detect

输出结果：

Temperature: 25.25°C

用c写一个一直 ping 一个ip地址 如果ping不到就给ret值为1

以下是一个简单的 C 语言程序，可以一直 ping 一个 IP 地址，如果 ping 不通则返回 1：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netinet/ip_icmp.h>
#include <netdb.h>

#define PACKET_SIZE 4096
#define MAX_WAIT_TIME 5
#define MAX_NO_PACKETS 3

struct packet
{
    struct icmphdr hdr;
    char msg[PACKET_SIZE-sizeof(struct icmphdr)];
};

unsigned short checksum(void *b, int len)
{
    unsigned short *buf = (unsigned short *)b;
    unsigned int sum = 0;
    unsigned short result;

    for (sum = 0; len > 1; len -= 2)
        sum += *buf++;

    if (len == 1)
        sum += *(unsigned char*)buf;

    sum = (sum >> 16) + (sum & 0xFFFF);
    sum += (sum >> 16);
    result = ~sum;
    return result;
}

int ping(char *host)
{
    struct hostent *hname;
    struct sockaddr_in addr_ping;
    int sockfd, i, len, flag = 1, flag_recv = 1;
    struct packet pkt;
    struct timeval tv_begin, tv_end, tv_interval;
    float rtt = 0;

    memset(&addr_ping, 0, sizeof(addr_ping));
    addr_ping.sin_family = AF_INET;

    if ((hname = gethostbyname(host)) == NULL)
    {
        printf("Unknown host %s\n", host);
        return 1;
    }

    memcpy(&addr_ping.sin_addr, hname->h_addr, sizeof(addr_ping.sin_addr));
    printf("PING %s (%s): %d bytes data in ICMP packets.\n", hname->h_name, inet_ntoa(addr_ping.sin_addr), (int)sizeof(struct packet));

    if ((sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)) < 0)
    {
        printf("socket error\n");
        return 1;
    }

    while (flag)
    {
        flag_recv = 1;
        memset(&pkt, 0, sizeof(pkt));
        pkt.hdr.type = ICMP_ECHO;
        pkt.hdr.code = 0;
        pkt.hdr.checksum = checksum(&pkt, sizeof(pkt));

        if (sendto(sockfd, &pkt, sizeof(pkt), 0, (struct sockaddr *)&addr_ping, sizeof(addr_ping)) < 0)
        {
            printf("sendto error\n");
            continue;
        }

        gettimeofday(&tv_begin, NULL);

        len = sizeof(addr_ping);

        if (recvfrom(sockfd, &pkt, sizeof(pkt), 0, (struct sockaddr *)&addr_ping, (socklen_t *)&len) < 0)
        {
            printf("recvfrom error\n");
            flag_recv = 0;
        }
        else
        {
            gettimeofday(&tv_end, NULL);

            tv_interval.tv_sec = tv_end.tv_sec - tv_begin.tv_sec;
            tv_interval.tv_usec = tv_end.tv_usec - tv_begin.tv_usec;

            rtt = tv_interval.tv_sec * 1000.0 + tv_interval.tv_usec / 1000.0;
            printf("%d bytes from %s: icmp_seq=%u ttl=%d time=%.1f ms\n", sizeof(pkt), inet_ntoa(addr_ping.sin_addr), pkt.hdr.un.echo.sequence, pkt.hdr.un.echo.sequence, rtt);
            flag_recv = 1;
        }

        sleep(1);

        if (!flag_recv)
        {
            flag = 0;
            printf("ping %s fail\n", host);
            close(sockfd);
            return 1;
        }

        if (i >= MAX_NO_PACKETS)
        {
            flag = 0;
        }
    }

    close(sockfd);
    return 0;
}

int main(int argc, char *argv[])
{
    if (argc < 2)
    {
        printf("Usage: %s <hostname>\n", argv[0]);
        return 1;
    }

    return ping(argv[1]);
}

注意：该程序需要在 Linux 环境下运行，并且需要 root 权限才能发送 ICMP 包。