How to handle args in Linux by C Language

Please reffer to getopt-优雅地处理命令行参数 | 守望的个人博客 (yanbinghu.com).

There is one mistake in this blog.

It seems that he just used the “-n” option, but forgot to add a parameter.

//one example about sleep and args
//this is my watering program
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <pigpio.h>
#include <string.h>
#include <signal.h>
extern int optind, opterr, optopt;
extern char *optarg;
void sig_handler(int num)
{
    gpioWrite(18, 0);
    printf("Interupted, exiting program...\n");
    printf("\nrecvive the signal is %d\n", num);
    exit(-1);
}
int main(int argc, char *argv[])
{
    int c = 0;
    int times = 0;
    printf("There are %d args\n", argc);
    if (argc != 2 && argc != 3)
    {
        printf("Wrong args\n");
        printf("use -f to water your flower fully\n");
        printf("use -d to water your flower in daily water\n");
        printf("use -h t to water your flower in t times\n");
        exit(0);
    }
    while (EOF != (c = getopt(argc, argv, "fdh:")))
    {
        switch (c)
        {
        case 'f':
            printf(":Fully:\n");
            times = 30;
            break;
        case 'd':
            printf(":Daily:\n");
            times = 3;
            break;
        case 'h':
            printf(":Manual mode:\n");
            times = atoi(optarg);
            break;
        case '?':
            printf("Unknow\n");
            exit(0);
            break;
        default:
            break;
        }
    }
    gpioInitialise();
    if (gpioSetMode(18, PI_OUTPUT) < 0)
    {
        printf("Failed\n");
        exit(0);
    }
    else
    {
        printf("Pigpio initialised ...\n");
    }
    gpioWrite(18, 0);
    printf("Watering...\n");
    signal(SIGINT, sig_handler);
    for (int i = 0; i < times; i++)
    {
        printf("The %d th time \n", i + 1);
        gpioWrite(18, 1);
        sleep(30);
        printf("%d th time dome. System cooling...\n",i+1);
        gpioWrite(18, 0);
        sleep(50);
    }
    printf("Done.\n");
    gpioWrite(18, 0);
    return 0;
}

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