c program to display numbers from 1 to n and their sum

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

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

display1(n);
printf("\n");

display2(n);
printf("\n");

printf("sum = %d\n", summation(n));
    getch();
}
int summation( int n)
{
if(n==0)
 return 0;
return ( n + summation(n-1) );
}

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

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