c語言 用庫函數(shù)計(jì)算兩日期相差的天數(shù)

#include?stdio.h

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#include?stdlib.h

#include?string.h

#include?math.h

#include?time.h

int??get_days(const?char*?from,?const?char*?to);

time_t?convert(int?year,int?month,int?day);

int?main()

{

const?char*?from="2013-3-15";

const?char*?to="2015-8-14";

int?days=get_days(from,to);

printf("From:%s\nTo:%s\n",from,to);

printf("%d\n",days);

return?0;

}

time_t?convert(int?year,int?month,int?day)

{

struct?tm?info={0};

info.tm_year=year-1900;

info.tm_mon=month-1;

info.tm_mday=day;

return?mktime(info);

}

int??get_days(const?char*?from,?const?char*?to)

{

int?year,month,day,fromSecond,toSecond;

sscanf(from,"%d-%d-%d",year,month,day);

fromSecond=(int)convert(year,month,day);

sscanf(to,"%d-%d-%d",year,month,day);

toSecond=(int)convert(year,month,day);

return?(toSecond-fromSecond)/24/3600;

}

From:2013-3-15

To:2015-8-14

882

Press?any?key?to?continue

這才算是用了庫函數(shù)了···

用c語言編寫一個函數(shù),功能是算出每個月的天數(shù)

int?GetMonthDays(int?year,int?month)

{

switch(month)

{

case?1:

case?3:

case?5:

case?7:

case?8:

case?10:

case?12:

return?31;

break;

case?4:

case?6:

case?9:

case?11:

return?30;

break;

case?2:

if((year%4==0??year%100!=0?)?||?(year%400==0))

{

return?29;

}

else

{

return?28;

}

break;

default:

printf("month?error!");

return?0;

break;

}

}

給定年月日 怎樣用C語言編程計(jì)算2個日期之間的時間天數(shù)

1970 年以后的時間，可以用 time.h 里的函數(shù)計(jì)算。時間精度為秒。按題目要求，輸出時間單位用天。程序如下：

#include stdio.h

#include time.h

time_t YMD_hhmmss_2_s70(int Y, int M, int D, int hh, int mm, int ss){

struct tm *target_tm;

time_t tt;

time (tt);

target_tm=localtime(tt);

target_tm-tm_year = Y - 1900;

target_tm-tm_mon= M - 1;

target_tm-tm_mday = D;

target_tm-tm_hour = hh; // hour

target_tm-tm_min = mm;

target_tm-tm_sec = ss;

tt = mktime(target_tm); // from tm to time_t (s)

return tt;

}

int main()

{

int y1,m1,d1,y2,m2,d2;

time_t t1,t2;

int dt;

printf("input y1 m1 d1: ");

scanf("%d %d %d",y1,m1,d1);

printf("\ninput y2 m2 d2: ");

scanf("%d %d %d",y2,m2,d2);

t1 = YMD_hhmmss_2_s70(y1,m1,d1,0,0,0);

t2 = YMD_hhmmss_2_s70(y2,m2,d2,0,0,0);

dt = (t2-t1)/(24*3600);

printf("\ndt=%d\n",dt);

return 0;

}

這里未包含日期的合法性判斷。

1970 年以前 要另寫程序。某年的日子是當(dāng)年的第幾天可用下面函數(shù)得出：

int YMD_2_JD(int Y, int M, int D){

const short MonthDay[]={0,31,28,31,30,31,30,31,31,30,31,30,31};

int JD,i;

JD=D;

for (i=0;iM;i++) JD+=MonthDay[i];

if (((Y%4==0)(Y%100!=0)||(Y%400==0)) (M2)) JD++;

return JD;

}

整年的天數(shù)，涉及閏年的判斷：

某年是否閏年，用 (Y%4==0)(Y%100!=0)||(Y%400==0) 判斷。閏年366天，平年365天。 有了這些，寫程序不難。

未考慮公元前的年月日計(jì)算。