#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <sys/ioctl.h>int main(int argc, char **argv){    int i;    int ret;    int fd;    int press_cnt[4];        fd = open("/dev/buttons", 0);  // 打開(kāi)設(shè)備    if (fd < 0) {        printf("Can't open /dev/buttons\n");        return -1;    }    // 這是個(gè)無(wú)限循環(huán)，進(jìn)程有可能在read函數(shù)中休眠，當(dāng)有按鍵被按下時(shí)，它才返回    while (1) {        // 讀出按鍵被按下的次數(shù)        ret = read(fd, press_cnt, sizeof(press_cnt));        if (ret < 0) {            printf("read err!\n");            continue;        }         for (i = 0; i < sizeof(press_cnt)/sizeof(press_cnt[0]); i++) {            // 如果被按下的次數(shù)不為0，打印出來(lái)            if (press_cnt[i])                printf("K%d has been pressed %d times!\n", i+1, press_cnt[i]);        }    }        close(fd);    return 0;    }