// MyAccumulators1.h
// tom bailey   25 sep 06

// Declare and Define the Summer accumulator class.

#ifndef MY_ACCUMULATORS_H_
#define MY_ACCUMULATORS_H_

// A Summer is a Simple Accumulator that tracks the sum of 
//   values in its sequence.
class Summer {
public:
	// post: The sequence is empty.
	Summer();

	// pre:  The sequence is S.
	// post: The sequence is S, then x.
	void append( double x );

	// pre:  The sequence is S.
	// post: The sum for S has been returned.
	double operator()();

private:
	double sum;
};

Summer::Summer() 
: sum( 0.0 ) {
}

void Summer::append( double x ) {
	sum += x;
}

double Summer::operator ()() {
	return sum;
}
		
#endif