while loop in c programming

                while loop

#include<stdio.h>
#include<conio.h>
void main()
{
int a,b=0;
clrscr();
while(a<=9)
{
b=b+2;
printf("%d\n",b);

a++;
}
getch();
}


Output:
2
4
6
8
10
12
14
16
18
20

-----------------------------
                                                   
A program of the sum of the series 1+2×2+3×3+4×4+…………+n×n

#include<stdio.h>
#include<conio.h>
void main()
{
int i=0,j;
int n;
clrscr();
printf("Enter the value of n:");
scanf("%d",&n);
while(j<=n)
{
i=i+j*j;

j++;
}
printf("Sum=%d",i);
getch();
}

Output:
Enter the value of n:4
Sum=30

---------------------------------------------------

#include<stdio.h>
#include<conio.h>
void main()
{
int i=0,j=1;
int n;
clrscr();
printf("Enter the value of n:");
scanf("%d",&n);
printf("The series=\n");
while(j<=n-1)
{
printf("%d+",j*j);
i=i+j*j;

j++;
}
printf("%d",n*n);
i=i+n*n;
printf("\nSum=%d",i);

getch();
}


Output:
Enter the value of n:4
The series=
1+4+9+16
Sum=30