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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 <stdlib.h>
#include <string.h>
int isDateArgument(char* dateString) {
const int MONTHS[] = {31,0,31,30,31,30,31,31,30,31,30,31};
int i, day, month, year;
char buffer[5];
/* 'today' is a valid date */
if (strcmp(dateString, "today") == 0)
return 1;
/* Numeric dates must be eight characters long */
if (8 != strlen(dateString))
return 0;
/* Check that the date is entirely formed of numbers */
for (i = 0; i < 8; i++) {
if (dateString[i] < '0' || dateString[i] > '9')
return 0;
}
/* Check that the date exists */
memset(buffer, 0, 5);
strncpy(buffer, dateString + 6, 2);
day = atoi(buffer);
strncpy(buffer, dateString + 4, 2);
month = atoi(buffer);
month -= 1;
strncpy(buffer, dateString, 4);
year = atoi(buffer);
/* Validate month */
if (month < 0 || month > 11)
return 0;
/* Validating dates is simple when the date does not fall into February */
if (1 != month) {
if (day < 1 || day > MONTHS[month])
return 0;
} else {
int feb = 28;
/* Februarys are a bit tougher issue */
if (0 == year % 4) {
if (0 == year % 100) {
if (0 == year % 400) {
feb = 29;
} else {
feb = 28;
}
} else {
feb = 29;
}
}
if (day < 1 || day > feb)
return 0;
}
/* Avoid user from using dates before 16000301, since those will result in
incorrect output */
if(16000301 > atoi(dateString))
return 0;
return 1;
}
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