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/* datedif - calculates the difference in days between two dates
* Copyright (C) 2000 Micael Widell contact: xeniac@linux.nu
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include <time.h>
#include <stdlib.h>
#include <string.h>
/* Gaus's formula - days since 1.3.1600 (Gregorian calendar) */
int days(register int n, register int m, register int y)
{
register int cy;
if((m -= 2) <= 0){
m += 12; y--;
}
y -= 1600; cy = y/100;
return 365*y+y/4-cy+cy/4+367*m/12+n-31;
}
double dateCalc(char * date1, char * date2){
/* Declare the needed variables */
char* date[2];
struct tm *date_tm[2];
time_t date_time_t[2];
double dateDifference;
int isToday[2] = { 0, 0 };
char buffer[5];
int day[2], month[2], year[2], i;
date[0] = date1;
date[1] = date2;
/* If any of the arguments are "today", then include today's date in the
right variables */
for(i = 0; i < 2; i++){
if(!strcmp(date[i], "today")){
time(&date_time_t[i]);
date_tm[i] = localtime(&date_time_t[i]);
day[i] = (*date_tm[i]).tm_mday;
month[i] = (*date_tm[i]).tm_mon + 1;
year[i] = (*date_tm[i]).tm_year + 1900;
isToday[i] = 1;
}
}
/* Cut out the year, month and day from 8-digit datestrings */
for (i = 0; i < 2; i++){
if(!isToday[i]){
memset(buffer, 0, 5);
strncpy(buffer, &date[i][6], 2);
day[i] = atoi(buffer);
strncpy(buffer, &date[i][4], 2);
month[i] = atoi(buffer);
strncpy(buffer, date[i], 4);
year[i] = atoi(buffer);
}
}
/* Calculate the difference */
dateDifference = days(day[1], month[1], year[1]) - days(day[0], month[0], year[0]);
return dateDifference;
}
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