Calendar in Plain C

Here is the code which displays the Calendar of the month entered by the user.

Code:

#include<stdio.h>
#include<conio.h>

#define Y 1900             /*1/1/1900 monday*/

void days(int *,int *);
void display(int *, int);

int _MONTH[]={{31},{28},{31},{30},{31},{30},{31},{31},{30},{31},{30},{31}};

void main()
{
	char ch = 'y';
	int m,yr;
	do
	{
		printf("\nEnter month [1-12] ");
		scanf("%ld",&m);
		printf("Enter year ");
		scanf("%ld",&yr);
		if((yr%4==0)&&((yr%100!=0)||(yr%400==0)))
			_MONTH[1]=29;
		days(&m,&yr);
		printf("\n\n\n\nPress 'x' to EXIT\n");
		fflush(stdin);
		ch = getch();
	}while(ch != 'x');
}

void days(int *m,int *yr)
{
	int i,md=0,leap=0,track;
	unsigned int d,yrd;
	for(i=Y;i<*yr;i++)
	{
		if((i%4==0)&&((i%100!=0)||(i%400==0)))
			leap++;
	}
	for(i=0;i<(*m-1)&&(i<11);i++)
		md=md+_MONTH[i];
	yrd=(*yr-Y)*365;
	d=yrd+leap+md;
	track=d%7;
	display(&track,*m);
}

void display(int *track,int m)
{
	int t,dt,loop;
	t=*track;
	printf("\n\n\n\t\t");
	printf("MON\tTUES\tWED\tTHURS\tFRI\tSAT\tSUN\n\n");

	for(loop=0;loop<t+2;loop++) /*t+2 due to two additional \t*/
		printf("\t");

	for(dt=1;dt<=_MONTH[m-1];dt++)
	{
		if(t%7==0 && t!=0)
			printf("\n\n\t\t");
		printf("%d",dt);
		printf("\t");
		t++;
	}
}

Test Run output

Code:

Enter month [1-12] 12
Enter year 1979



                MON     TUES    WED     THURS   FRI     SAT     SUN

                                                        1       2

                3       4       5       6       7       8       9

                10      11      12      13      14      15      16

                17      18      19      20      21      22      23

                24      25      26      27      28      29      30

                31



Press 'x' to EXIT

 

It shows. Just debug it out if it says the printf with some correct values.