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/*
* Copyright (C) 2014 Ho Chi Minh city University of Technology (HCMUT)
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup examples
* @{
*
* @file
* @brief Some functions implementaion in C.
*
* @author DangNhat Pham-Huu <51002279@hcmut.edu.vn>
*
* @}
*/
#include "c_functions.h"
#define IS_LEAP_YEAR(year) ((year%4 == 0) ? ((year%100 == 0) ? ((year%400 == 0) ? 1 : 0) : 1): 0)
int hello(void)
{
puts("Hello world in a C function");
return 0;
}
int day_of_week(int day, int month, int year)
{
int count, sum_of_days;
/* 1/1/2000 is Saturday */
int first_day = 6;
/* check input date */
if (year < 2000) {
printf("Sorry buddy, your date should be >= 1/1/2000!\n");
return -1;
}
if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12) {
if (day > 31 || day < 1) {
printf("Sorry buddy, your date is not correct!\n");
return -1;
}
}
else if (month == 2) {
if (IS_LEAP_YEAR(year)) {
if (day > 29 || day < 1) {
printf("Sorry buddy, your date is not correct!\n");
return -1;
}
}
else {
if (day > 28 || day < 1) {
printf("Sorry buddy, your date is not correct!\n");
return -1;
}
}
}
else {
if (day > 30 || day < 1) {
printf("Sorry buddy, your date is not correct!\n");
return -1;
}
}
/* date is okay, convert... */
sum_of_days = 0;
for (count = 2000; count < year; count++) {
sum_of_days += (((IS_LEAP_YEAR(count) == 1) ? 366 : 365)) % 7;
}
for (count = 1; count < month; count++) {
if (count == 1 || count == 3 || count == 5 || count == 7 || count == 8 || count == 10 || count == 12) {
sum_of_days += 31 % 7;
}
else if (count == 2) {
if (IS_LEAP_YEAR(year)) {
sum_of_days += 29 % 7;
}
else {
sum_of_days += 28 % 7;
}
}
else {
sum_of_days += 30 % 7;
}
}
sum_of_days += (day - 1) % 7;
return (sum_of_days + first_day) % 7;
}