// Bob Myers -- functions2.cpp
//
// Example illustrating some function declarations, definitions, calls
//
// Better layout than functions1.cpp.  This one has prototypes at the top

#include <stdio.h>

#define TRUE 1
#define FALSE 0

// function PROTOTYPES listed here.  

int Sum(int x, int y, int z);
double Average (double a, double b, double c); 
int InOrder(int x, int y, int z); 

// The prototypes above satisfy declare-before-use, so these functions can
//  be CALLED anywhere below this point.

int main()
{
   int i1, i2, i3;		// integers for input
   double d1, d2, d3;		// doubles for input

   double avg;			// to compute average
   int total;			// to compute the sum

   printf("Input three integers: ");
   scanf("%d %d %d", &i1, &i2, &i3);

   printf("Input three doubles: ");
   scanf("%lf %lf %lf", &d1, &d2, &d3);

   // samples of function calls

   total = Sum(i1, i2, i3);
   avg = Average(d1, d2, d3);

   printf("The sum of the three integers = %d\n", total);
   printf("The average of the three doubles = %f\n", avg);
 

   // note that we can place the call in the printf statements, which 
   //  prints the return values

   printf("The sum of 10, 14, and 18 = %d\n", Sum(10, 14, 18) );

   printf("The average of 1.3, 2.7, and 6.9 = %f\n", 
					Average(1.3, 2.7, 6.9) );

   // Notice that we can pass in integers where doubles are expected
   //   legal via automatic-type-conversion rules

   printf("The average of the three integers = %f\n", 
					Average(i1, i2, i3) );

   // Testing out the predicate function (InOrder)

   if (InOrder(i1, i2, i3))
	printf("The three integers were typed in ascending order\n");
   else
	printf("The three integers were NOT typed in ascending order\n");


   return 0;
}


// function definitions can appear in any order, since the prototypes
//  were listed at the top to handle declare-before-use

int Sum(int x, int y, int z)
// add the three parameters together and return the result
{  
   int answer;
   answer = x + y + z;
   return answer;
}
 
double Average (double a, double b, double c)
// add the parameters, divide by 3, and return the result
{
   return (a + b + c) / 3.0;
}

int InOrder(int x, int y, int z)
// answers yes/no to the question "are these parameters in order,
//  smallest to largest?"  Returns TRUE (1) for yes, FALSE (0) for no.
//  (This kind of function often known as a "predicate function")
{
   if (x <= y && y <= z)
        return TRUE;
   else
        return FALSE;
}