<strong><span style="font-size:14px;">C语言  --   定时关机程序</span></strong>
<strong></strong><span style="font-size:14px;"></span>
<strong><span style="font-size:14px;">特别注意：</span></strong>
<strong><span style="font-size:14px;"> 1.从接收到的char * 类型转换为 int ，一定不能使用(int)这种方式来转换，要用atoi()</span></strong>
<strong><span style="font-size:14px;">   使用方式：原型: int atoi(const char *nptr);</span></strong>
<strong><span style="font-size:14px;">2. 多个字符串合并，使用sprintf()</span></strong>
<strong><span style="font-size:14px;">   使用方式：sprintf(char *buffer,const char * format[,argument,...])</span></strong>
<strong><span style="font-size:14px;">   以下有使用方式</span></strong>
<strong><span style="font-size:14px;">
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#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <time.h>
 
 
int isNumber(char *a);
void getCurrentDate(int seconds);  

int main(){
  printf("欢迎进入定时关机系统！\n");
  getCurrentDate(0);

  char str[2]; 
  char flag = 1;
  while(flag){
    printf("输入A定时关机，输入C取消定时关机\n"); 
    gets(str);
    if(strcmp(str,"a")==0) { 
      printf("请输入时间的秒数：\n");
      char seconds[10];
      while(1){ 
        gets(seconds);   
        if(isNumber((char*)seconds))
          break;
        else{
          printf("输入的秒数不正确，请重新给输入！\n");
          continue; 
        }
      }  
      int temp_seconds = atoi(seconds);
      getCurrentDate(temp_seconds);
      char shutdown[50] = "shutdown -s -t ";
      strcat(shutdown,seconds);
      system(shutdown);
      system("pause");
      break;
    } else if(strcmp(str,"C")==0 || strcmp(str,"c")==0) {
      system("shutdown -a");
      printf("已经取消定时关机\n");
      system("pause");
      break;
    }else{
      printf("输入的值不正确，请重新输入!\n"); 
      flag=1;
    }
  }
  
  return 0;
}

//判断字符串是否是数字
int isNumber(char *a){
  char flag=1;
  int len = strlen(a);
  for(int i=0;i<len;i++){
    if(isdigit(a[i])==0){
      flag = 0;
      break;
    }
  }
  if(flag) 
    return 1;
  else
    return 0;
}
  
//获取系统当前时间
void getCurrentDate(int seconds){
  time_t rawtime;
  struct tm *timeinfo,*timeinfo2;
  time(&rawtime); 
  if(seconds > 0){
    rawtime += seconds; 
  }
  timeinfo = localtime(&rawtime); 
  int year = timeinfo->tm_year + 1900; 
  int month = timeinfo->tm_mon+1; 
  int day = timeinfo->tm_mday; 
  int hour = timeinfo->tm_hour; 
  int min = timeinfo->tm_min; 
  int secs = timeinfo->tm_sec; 
   
  char *str = (char*)malloc(sizeof(char)*100);   
  memset(str,0,100);
  //多个值合并字符串
  if(seconds > 0){
    sprintf(str,"在%d年%d月%d日 %d时%d分%d秒后关机...",year,month,day,hour,min,secs); 
  }else{
    sprintf(str,"现在时间是：%d年%d月%d日 %d时%d分%d秒 ",year,month,day,hour,min,secs);  
  } 
  puts(str);
  free(str);
}