//Examples for cs 149

//  2 forms of functions:
//     1 searches an array and returns a value.
//       returns the average of the elements in an array.
//     2 changes contents of an array.

#include <iostream.h>
#include <fstream.h>

int main()
{
	const int N=500;  // assume N is large enough
	int InCt;
	double X[N], Y[N];
	double y;
	fstream Data;

	double ArrayAvg( double Y[], int ArraySize );
	void ArrayChg( double Y[], int ArraySize );
	double Max( double Y[], int ArraySize );

	// Load array.
	Data.open( "SampleData.txt", ios::in );
	InCt = 0;
	while ( Data >> X[InCt] ) {
		InCt++;
	}
	Data.close();
	cout << InCt << " values read from file." << endl;

	// Find avgerage, etc.
	y = ArrayAvg( X, InCt ) * 2;
	cout << "Max value from file: " << Max( X, InCt ) << endl;
	cout << "Twice the average is: " << y << endl;

	for ( int i=0; i<InCt; i++ )
		Y[i]=X[i]*5 - 1;

	// Change array
	ArrayChg( Y, InCt );
	y = ArrayAvg( Y, InCt );
	cout << "The new average is: " << y << endl;

	ArrayChg( X, InCt );
	y = ArrayAvg( X, InCt );
	cout << "The new average is: " << y << endl;

	ArrayChg( X, InCt );
	y = ArrayAvg( X, InCt );
	cout << "The new average is: " << y << endl;

	return 0;

}

// ---
//  Definition of function ArrayAvg
//    computes the average of the elements in the array
double ArrayAvg( double Y[], int ArraySize )
{
	double Sum = 0;

	for ( int i=0; i<ArraySize; i++ )
		Sum += Y[i];
	return Sum/ArraySize;
}

// Definition of function ArrayChg
//   changes the contents of the array be adding 2 to each
//   array element
void ArrayChg( double Z[], int Size )
{
	for ( int i=0; i<Size; i++ )
		Z[i]+= 2;
}

// Definition of function Max
//   find the maximal value in an array.
double Max( double Z[], int Size )
{
	double TempMax;

	TempMax = Z[0];
	for ( int i= 1; i<Size; i++ )
		if ( TempMax < Z[i] )
			TempMax = Z[i];
	return TempMax;
}