C语言零碎记录之Linux下C语言关于时间的函数

#ifndef __TIME_T
#define __TIME_T     /* 避免重复定义 time_t */
typedef long     time_t;    /* 时间值time_t 为长整型的别名*/
#endif

int getDaysSinceYear(){//0-365 not including this year!
  time_t t;time(&t);
  struct tm *p;
  p=localtime(&t);
  return p->tm_yday;
}


int getDaysSinceYear2(int year,int mon,int day){//这个是另外一个算法,范围1-366.所以应该-1 来达到上面的目的
    int myyday=0;
    mon--;//last Month and before
    while(mon>0){//from 1 to last month!!!!!!!!!!
        switch(mon){
            case 1:
            case 3:
            case 5:
            case 7:
            case 8:
            case 10:
            case 12:myyday+=31;break;
            case 4:
            case 6:
            case 9:
            case 11:myyday+=30;break;
            case 2:myyday+=28;break;
            default:break;
        }
        mon--;
    }
    myyday+=day;//And Plus this month's days
    if(year%4==0)myyday+=1;// 2 yue if it is 29 days!!!
    return myyday;
}

int getSecondsByTime(int year,int month,int days,int hour,int minute,int second){
//input format : 2011 11 11 11 11 11

printf("%d-%d-%d %d:%d:%d == input time\n",year,month,days,hour,minute,second);

    int daySecOnds=24*60*60;
    secOnds=hour*60*60+minute*60+second;//this year!
    seconds+=(getDaysSinceYear())*daySeconds;
    year--;//so not including this year!
    for(;year>=1970;year--){//1970 - last year!
        seconds+=365*daySeconds;
        if(year%4==0)seconds+=daySeconds;
    }
    seconds-=8*60*60;//UTC Time .Current +8 hours beijing!
    printf("%d == seconds(1970) in UTC\n",seconds);
    return seconds;
}