CALCULATE DAY USING DATE
#include<stdio.h> #include<conio.h> main() { int d,m,y,ce,year,ly,le=0,day; clrscr(); ...

https://www.computersprofessor.com/2016/06/calculate-day-using-date.html
#include<stdio.h>
#include<conio.h>
main()
{
int d,m,y,ce,year,ly,le=0,day;
clrscr();
printf("ENTER DAY,MONTH,YEAR");
scanf("%d%d%d",&d,&m,&y);
ce=y/100+1;
ce=ce%4;
switch(ce)
{
case 1:
ce=6;
break;
case 2:
ce=4;
break;
case 3:
ce=2;
break;
case
0:
ce=0;
break;
}
year=y/100;
ly=year/4;
le=year%4;
if(le==0)
{
if(m<=2)
{
le=-1;
}
}
else
{
le=0;
}
switch(m)
{
case 1:
m=0;
break;
case 2:
m=3;
break;
case 3:
m=3;
break;
case
4:
m=6;
break;
case 5:
m=1;
break;
case 6:
m=4;
break;
case 7:
m=6;
break;
case 8:
m=2;
break;
case 9:
m=5;
break;
case
10:
m=10;
break;
case
11:
m=3;
break;
case
12:
m=5;
break;
}
day=ce+year+ly+m+d+le;
day=day/7;
switch(day)
{
case 1:
printf("MONDAY");
break;
case 2:
printf("TUESDAY");
break;
case
3:
printf("WEDNESDAY");
break;
case
4:
printf("THURSDAY");
break;
case
5:
printf("FRIDAY");
break;
case 6:
printf("SATURDAY");
break;
case 0:
printf("SUNDAY");
break;
}
getch();
}
Output: