display numbers from 1 to n and their sum

/*P5.2 Program to display numbers from 1 to n and their sum*/

#include<stdio.h>
int summation(int n);
void display1(int n);
void display2(int n);

main( )
{
    int n;
    printf("Enter number of terms : ");
    scanf("%d", &n);
   
    display1(n);
    printf("\n");

    display2(n);
    printf("\n");
   
    printf("sum = %d\n", summation(n));   
}/*End of main()*/
int summation( int n)
{
    if(n==0)
        return 0;
    return ( n + summation(n-1) );
}/*End of summation()*/

/*displays in reverse order*/
void display1(int n)
{
    if( n==0 )
       return;
    printf("%d ",n);   
    display1(n-1);
}/*End of display1()*/

void display2(int n)
{
    if( n==0 )
       return;
    display2(n-1);
    printf("%d ",n);   
}/*End of display2()*/