/* Bai tap 1_100 - Tinh thu cua ngay */

#include <stdio.h>

struct date

{

int month;

int day;

int year;

} date_1;

long int funct1 (int y,int m)

{

long int result;

if ( m <= 2 )

y -= 1;

result = y;

return (result);

}

long int funct2 (int m)

{

long int result;

if ( m <= 2 )

result = m + 13;

else

result = m + 1;

return(result);

}

long int day_count (int m, int d, int y)

{

long int number;

number = 1461 * funct1(y,m) / 4 + 153 * funct2(m) / 5 + d;

return (number);

}

void main ()

{

long int number_of_days1;

int day_of_week;

printf ("Nhap vao mot ngay (dd mm yyyy), vd 12 03 1999

");

scanf ("%d %d %d", &date_1.day, &date_1.month, &date_1.year);

number_of_days1 = day_count (date_1.month, date_1.day, date_1.year);

printf ("

Ngay la : " );

day_of_week = (number_of_days1 - 621049) % 7;

switch (day_of_week)

{

case 0 :

printf ("Chu Nhat,");

break;

case 1 :

printf ("Thu Hai,");

break;

case 2 :

printf ("Thu Ba,");

break;

case 3 :

printf ("Thu Tu,");

break;

case 4 :

printf ("Thu Nam,");

break;

case 5 :

printf ("Thu Sau,");

break;

case 6 :

printf ("Thu Bay,");

break;

}

getch();

}