CTime tm类计算日期间隔

搜索查询日期间隔的方法的时候，找到tm类。这个类可以实现简单的日期计算，比如设置好年月日就能从tm_wday知道是星期几。

struct tm {
        int tm_sec;     /* seconds after the minute - [0,59] */
        int tm_min;     /* minutes after the hour - [0,59] */
        int tm_hour;    /* hours since midnight - [0,23] */
        int tm_mday;    /* day of the month - [1,31] */
        int tm_mon;     /* months since January - [0,11] 当前月减去1*/
        int tm_year;    /* years since 1900 * 当前年减去1900/
        int tm_wday;    /* days since Sunday - [0,6] */
        int tm_yday;    /* days since January 1 - [0,365] */
        int tm_isdst;   /* daylight savings time flag */
        };

#include <cstdio>#include <ctime>#include <iostream>#include <cstring>#include <conio.h>using std::memset;using std::tm;using std::mktime;using std::cout;using std::endl;int main(){    struct tm Time1,Time2;    //需要全部重置    memset(&Time1, 0, sizeof(tm));    memset(&Time2, 0, sizeof(tm));    time_t Res1,Res2;    //时间范围有限制，似乎是[70-138]，即1970-2138    Time1.tm_year = 138;    Time1.tm_mon = 6;    Time1.tm_mday = 1;    Time1.tm_hour = 1;    Time1.tm_min = 2;    Time1.tm_sec = 3;    Time2.tm_year = 110;    Time2.tm_mon = 6;    Time2.tm_mday = 1;    Time2.tm_hour = 1;    Time2.tm_min = 2;    Time2.tm_sec = 3;    Res1 = mktime(&Time1);    Res2 = mktime(&Time2);    printf("%ld %ld\n", Res1, Res2);    int DayNum = (Res1 - Res2)/(24*60*60);    cout << DayNum << endl;    //也可以这样设置【秒，分，小时，天，月，年】    struct tm t1 = { 0, 0, 0, 4, 7, 80 };   // Warning! month between [0, 11]    struct tm t2 = { 0, 0, 0, 7, 8, 104 }; // Year from 1900    int days = (mktime(&t2) - mktime(&t1)) / (24*60*60);    cout << days << endl;} 

/* mktime example: weekday calculator */#include <stdio.h>      /* printf, scanf */#include <time.h>       /* time_t, struct tm, time, mktime */int main (){time_t rawtime;struct tm * timeinfo;int year, month ,day;const char * weekday[] = { "Sunday", "Monday","Tuesday", "Wednesday","Thursday", "Friday", "Saturday"};/* prompt user for date */printf ("Enter year: "); scanf ("%d",&year);printf ("Enter month: "); scanf ("%d",&month);printf ("Enter day: "); scanf ("%d",&day);/* get current timeinfo and modify it to the user's choice */time ( &rawtime );timeinfo = localtime ( &rawtime );timeinfo->tm_year = year - 1900;timeinfo->tm_mon = month - 1;timeinfo->tm_mday = day;/* call mktime: timeinfo->tm_wday will be set */mktime ( timeinfo );printf ("That day is a %s.\n", weekday[timeinfo->tm_wday]);return 0;}