#include <stdio.h>
/* C Prrogram to print EVEN numbers from 1 to N Using While loop*/
int main()
 {
  /*declare variable c as counter */
  int c;
  /*declare variable n to store a number */
  int n;
  /* Assign initial value to counter c from where we want to print the numbers */
  c=1;
  /*accept the value for n */
  printf("Enter any Number N: ");
  scanf("%d",&n);
  printf("Even Numbers from 1 to %d:\n",n);
  /* the while loop, that will print even numbers */

 while(c<=n) {
  /*the condition to check Even number */
  if(c%2 == 0)
   printf(" %d ",c);
  /* increasing loop counter by 1 */
  c++;
 }
return 0;
}
Output:
Enter Value of N
10
Even Numbers from 1 to 10
2 4 6 8 10

2. Write a program in C to print Even numbers from 1 to N using do while loop.

#include <stdio.h>
/* C Prrogram to print Even numbers from 1 to N Using do While loop*/
int main()
  {
   /*declare variable c as counter */
  int c;
  /*declare variable n to store limit */
   int n;
  /*assign initial value
to counter c from where we want to print the numbers */
  c=1;
 /*accept the value for n */
  printf("Enter the value of N: ");
  scanf("%d",&n);
  printf("Even Numbers from 1 to %d:\n",n);
  /* do while loop, that will print Even numbers */

do {
  /* the condition to check EVEN number */
  if(c%2 == 0)
   printf(" %d ",c);
  /* increasing loop counter c by 1 (c++) */
  c++;
  }while(c<=n);
return 0;
}
Output: Enter Value of N
10
Even Numbers from 1 to 10
2 4 6 10
Program Explanation:
1.In the program given above there are two variables declared
1.)n to store the limit and
2)variable c=1 as loop counter.
2. printf("Enter the value of N: ");
display message "Enter the value of N:"
10
"We enter the value 10"
scanf("%d",&n); Read the value entered by user and store it in n.
next printf() display message "Odd Numbers from 1 to 10"
3. control jumps in do while loop start executing condition c%2==0 (1%2!=0) The Condition is true and display 1.
value of c is increment by 1 and then while(c<=n) condition(2<=10) is evaluated true
and body of do while loop is executed.
the condition if(c%2==0) is tested which is false , value of c incremented (c++)by 1 now becomes c=3 .
Next while(c<=n) condition is tested(3<=12) which is true.

Again body of loop executes , this process continues while value of c<=10.
control jumps out of loop as soos as value of c becomes 8 and stops the program.