Write a program to print a summation using array

#include<stdio.h>
main()
{
int a[n],i,sum=0;
printf("\nEnter the Numbers:\n");
for(i=0;i<n;i++)
{
scanf("%d",&a[i]);
sum=sum+a[i];
}
printf("\nThe Result of summation is : %d",sum);
return 0;
}