find area of a given curve usinh trapezoidal rule

#include <stdio.h>
#include <conio.h>
#include <math.h>
#define e 2.71828
float func(float);
int main ()
{
float n,a,b,i;
float sum=0,term,area,h;
printf("entr no of trp ,up lim,low lim")  ;
scanf("%d %d %d",&n,&b,&a);
for(i=2;i<=n;++i)
{term=func(i);
sum=sum+term;}
h=(b-a)/n;
area=0.5*h*(func(1)+func(n+1)+2*sum);
printf("%lf",area);
                      
      getch();
     return 0;
}

float func(float x)
{float y;
y=4*pow(e,-x);
return y;
}