Linux uses C language to get the system boot length

The idea is to get the system start-up time by reading/proc/uptime.
Using the command cat/proc/uptime

The following information can be seen through the man proc:
/proc/uptime:this file contains, numbers:the uptime of the system (seconds), and the amount of time spent in idle proc ESS (seconds).
The first is the system's startup time, and the second is the idle time of the system. Two units are in seconds.

#include <stdio.h>#include <string.h>#include <sys/time.h>#include <stdlib.h>structTimeval Timeget (void){structTimeval now;unsigned Chartimestr[ -] = {0};unsigned Charuptimestr[ -] = {0};unsigned Char* DOTADDR;unsigned LongSecondCharError =0;    FILE * Timefile = NULL; Timefile = fopen ("/proc/uptime","R");if(!timefile) {printf("[%s:line:%d] Error opening '/proc/uptime '", __file__,__line__); Error =1;GotoOut }if(Fread (TIMESTR,sizeof(Char), -, timefile)) = =0)    {printf("[%s:line:%d] read '/proc/uptime ' ERROR", __file__,__line__); Error =1;GotoOut } dotaddr =STRCHR(Timestr,'. ');if((Dotaddr-timestr +2) < -)memcpy(Uptimestr, TIMESTR, Dotaddr-timestr +2);Else{printf("[%s:line:%d] uptime string is too long", __file__,__line__); Error =1;GotoOut } Uptimestr[dotaddr-timestr +2] =' + '; Out:if(Error) {now.tv_sec =0; Now.tv_usec =0; }Else{now.tv_sec = Atol (UPTIMESTR); Now.tv_usec =0; } fclose (Timefile);returnNow;}intMain () {structTimeval uptime; Uptime = Timeget ();printf("uptime =%lu\n", uptime.tv_sec);return 0;}

Operation Result:

Linux uses C language to get the system boot length