/* File: func4.c
   Returning a function in C
*/

#include <stdio.h>


float total (float x, int m) {
   return x + (float) m ;
}


float withInterest (float x, int m) {
   return x * 1.1 + (float) m ;
}



float apply( float (*f) (float, int), int A[], int n) {

   float accumulate = 0.0 ;

   for (int i=0 ; i < n ; i++) {
      accumulate = f(accumulate, A[i] ) ;
   }

   return accumulate ;
}



float (*select (int pick)) (float, int) 
{
   if (pick == 0) 
      return total ; 
   else 
      return withInterest ;
}


int main () {
   int B[10] = { 10, 11, 12, 13, 14, 15, 16, 17, 18, 19} ;
   float result ;
   float (*func)(float, int) ;

   printf("Before:\n") ;
   for (int i=0 ; i < 10 ; i++) {
      printf("   B[%d] = %d\n", i, B[i]) ;
   }

   func = select(0) ;
   result = apply (func, B, 10) ;

   printf("\n\nAfter calling apply(total, B, 10):\n") ;
   printf("  result = %f\n", result) ;


   func = select(1) ;
   result = apply (func, B, 10) ;

   printf("\n\nAfter calling apply(withInterest, B, 10):\n") ;
   printf("  result = %f\n", result) ;

}