Sum and Average of 1 to 100 using For Loop

#include <stdio.h>

int main (){

     int sum=0,i;
     double avg;
     int a=0;
     for(i=1;i<=100;i++){

        a=a+1;
        sum=sum+a;

     }
     printf("%d is the Sum\n",sum);
     avg=sum/100;
     printf("%lf is the Average\n",avg);



     return 0;
}