According to the Gregorian calendar, it was Monday on the date 01/01/1900. If any year is input through the keyboard write a program to find out what is the day on 1st January of this year.

Solution ::

#include <stdio.h>
int main ()                                   //Monday-0
{                                             //Tuesday-1
   int c=0,m=1,i,y,p;                         //Wednesday-2
   printf("Enter a year: ");                  //Thursday-3
   scanf("%d",&y);                            //Friday-4
   for(i=1991;i<=y;i++)                       //Saturday-5
   {                                          //Sunday-6
       if((i%4)==0&&(i%100)!=0||(i%400)==0) //After 7 days,c = 0;(Monday, 1 week)
        {                                //If a year leap year, next year c=c+2
            c++;                              //if(c==0) ; c = 0 ; Monday
            p=i;                              //if(c==8) ; c = 1 ; Tuesday
        }                                     //c===day
        else if((i-1)==p)
            c=c+2;
       else
        c++;

        if(c==7)
            c=0;
        else if(c==8)
            c=1;
   }
   if(c==0)
    printf("MONDAY");
   else if (c==1)
    printf("TUESDAY");
   else if (c==2)
    printf("WEDNESDAY");
   else if (c==3)
    printf("THURSDAY");
   else if (c==4)
    printf("FRIDAY");
   else if (c==5)
    printf("SATURDAY");
   else if (c==6)
    printf("SUNDAY");
   return 0;
}

WAP whether a number is prime or not using function.

CODE ::

#include <stdio.h>
#include <math.h>
int check (int p);
int main ()
{
    int n;
    printf("Enter a number: ");
    scanf("%d",&n);
    if(check(n))
        printf("Prime\n");
    else
        printf("Not prime\n");
    return 0;
}
int check (int p)
{
    int i,f=0,limit;
    limit=sqrt(p);
    for(i=2;i<=limit;i++)
    {
        if(p%i==0)
        {
            f=1;
            break;
        }
    }
    if(f==0)
        return 1;

    return 0;
}

WAP to check that a given year is a leap year or not.

Definition of leap year:

Rule #1: A year is called leap year if it is divisible by 400.
For example: 1600, 2000 etc leap year while 1500, 1700 are not leap year.

Rule #2: If year is not divisible by 400 as well as 100 but it is divisible by 4 then that year are also leap year.

For example: 2004, 2008, 1012 are leap year.

CODE ::

#include <stdio.h>

void main ()

{

    int year;

    printf("Enter a year: ");

    scanf("%d",&year);

    if((year%4==0)&&(year%100!=0)||(year%400==0))

        printf("LEAP YEAR\n");

    else

        printf("NOT LEAP YEAR\n");

}

WAP to find out the sum of the following series.

                                                                        1 + x²/2! + x⁴/4! + x⁶/6! + …….xⁿ/n!

CODE : :

#include <stdio.h>

#include <math.h>

long long fact(int n);

int main ()

{

    long long i,x,n;

    double sum=1;

    printf("Enter x and n: ");

    scanf("%lld %lld",&x,&n);

    for(i=2;i<=n;i=i+2)

    {

        sum=sum+pow(x,i)/(double)fact(i);

    }

    printf("Sum is : %.3lf\n",sum);

}

long long fact(int n)

{

    if(n==1)

        return 1;

    return n*fact(n-1);

}

If a number 972 is entered through the keyboard, your program should print “Nine Seven Two”. Write the program such that it does this for any positive integers.

Code :::

#include <stdio.h>
int main ()
{
    char a[100];
    int i;
    printf("Enter a number: ");
    gets(a);
    for(i=0;i<a[i];i++)
    {
        if(a[i]=='0')
            printf("Zero ");
        else if(a[i]=='1')
            printf("One ");
        else if(a[i]=='2')
            printf("Two ");
        else if(a[i]=='3')
            printf("Three ");
        else if(a[i]=='4')
            printf("Four ");
        else if(a[i]=='5')
            printf("Five ");
        else if(a[i]=='6')
            printf("Six ");
        else if(a[i]=='7')
            printf("Seven ");
        else if(a[i]=='8')
            printf("Eight ");
        else if(a[i]=='9')
            printf("Nine ");
    }
    return 0;
}

WAP to input a number through the keyboard until a ‘.’ Every time a number is entered. The program should display whether it is greater than, less than or equal to the previous number.

Code  : :

#include<stdio.h>
int main()
{
    int num,a;
    scanf("%d",&a);
    while(scanf("%d",&num))
    {
         if(num == '.') break;
         else if(num>a)
            printf("Grater\n");
         else if(num<a)
            printf("Less\n");
         else if(num==a)
            printf("Equal\n");
         a=num;
    }
    return 0;
}