Comparing return value with output parameter in C++

return-value.cpp

#include <ctime>
#include <iostream>
#include <vector>
using namespace std;

typedef vector<int> IntVec;

const int MAX = 10000;

IntVec Function1( const int size )
{
    IntVec ivec;
	for ( int i = 0; i < size; ++i )
		ivec.push_back( i );
	return ivec;
}

void Function2( const int size, IntVec& ivec )
{
	for ( int i = 0; i < size; ++i )
		ivec.push_back( i );
	return;
}

int main()
{
	// *** New Object

	double time1 = 0.0;
	double time2 = 0.0;

	for ( int i = 0; i < MAX; ++i )
	{
		const int randVal = rand();

		// *** Function1

		clock_t begin1	= clock();
		IntVec ivec1	= Function1( randVal );
		clock_t end1	= clock();
		double timeSec1 = (end1 - begin1) / static_cast<double>( CLOCKS_PER_SEC );
		time1			+= timeSec1;

		// *** Function2

		clock_t begin2	= clock();
		IntVec ivec2;
		Function2( randVal, ivec2 );
		clock_t end2	= clock();
		double timeSec2 = (end2 - begin2) / static_cast<double>( CLOCKS_PER_SEC );
		time2			+= timeSec2;
	}

	cout << "New object ..." << endl;
	cout << "Function1: " << time1 << endl;
	cout << "Function2: " << time2 << endl;

	// *** Existing Object

	time1 = 0.0;
	time2 = 0.0;

	IntVec ivec3;

	for ( int i = 0; i < MAX; ++i )
	{
		const int randVal = rand();

		// *** Function1

		ivec3.clear();
		clock_t begin1	= clock();
		ivec3			= Function1( randVal );
		clock_t end1	= clock();
		double timeSec1 = (end1 - begin1) / static_cast<double>( CLOCKS_PER_SEC );
		time1			+= timeSec1;

		// *** Function2

		ivec3.clear();
		clock_t begin2	= clock();
		Function2( randVal, ivec3 );
		clock_t end2	= clock();
		double timeSec2 = (end2 - begin2) / static_cast<double>( CLOCKS_PER_SEC );
		time2			+= timeSec2;
	}

	cout << "Existing object ..." << endl;
	cout << "Function1: " << time1 << endl;
	cout << "Function2: " << time2 << endl;

	return 0;
}