Question

Write a C program to print and sum first n even numbers.​

Answer 1

Answer

→ C program to print and sum first n even numbers

║PROGRAM║

#include<stdio.h>

main()

{

 int i,n,sum=0;

 printf("Enter a number\n");

 scanf("%d",&n);

 for(i=0;i<=n;i++)

 {

   sum=sum+i;

 }

 printf("%d\n",sum);

}

║OUTPUT║

10

55

║EXPLANATION║

First we initialized i,n, and sum which is declared as zero.

A number is given by user (say 5).

Now the logic is:sum = sum+i

sum = 0+0=0

for next iteration i becomes '1' so sum=0+1=1

for next iteration i becomes '2' so sum=2+1=3

for next iteration i becomes '3' so sum=3+3=6

for next iteration i becomes '4' so sum=4+6=10

for next iteration i becomes '5' so sum=10+5=15

for next iteration i becomes '6' which is not less than or equal to 'n'(i.e 5 as we took a value for explanation) then the loop terminates and goes to the next line.

Then the value of sum which is '15' will be printed.