Question

Write program to store ten integers in an array and the program will do the
following
Find the average of even marks

Find how many prime integers inserted
Note: please solve it by c , not c++

Answer 1

#include <stdio.h>

int prime(int arr[])
{
    int i,j,count,k;
    count=0;
    for(i=0;i<10;i++)
    {
        k=0;
        for(j=1;j<=arr[i];j++)
        {
            //counting the number of factors for the array element
            if(arr[i]%j==0)
            {
                k++;
            }
        }
        //if the no of factor is equal to 2 
        //it will count it as prime
        if(k==2)
        {
            count++;
        }
    }
    //returning the number of prime numbers
    return count;
}
int main()
{
    int arr[10];
    int i,count,sum;
    //taking the array inputs
    printf("Enter ten array elements of integer type .\n");
    for(i=0;i<10;i++)
    {
        scanf("%d",&arr[i]);
    }
    sum=count=0;
    //calculating sum for the array index of even positions
    for(i=0;i<10;i=i+2)
    {
        sum=sum+arr[i];
        count++;
    }
    //printing the corresponding average
    printf("The average of the even marks : %d\n",(sum/count));
    sum=count=0;
    //calculating sum for the array elements which are even
    for(i=0;i<10;i++)
    {
        if(arr[i]%2==0)
        {
            sum=sum+arr[i];
            count++;
        }
    }
    //printing the corresponding average
    printf("The average of the even numbers : %d\n",(sum/count));
    //calling the function to count
    //the number of prime present in the array
    count=prime(arr);
    printf("The number of prime numbers present in the array is : %d\n",count);
    return 0;
}