(silly?) speed comparisons

[mk]

Rajanikanth Jammalamadaka wrote:
> Try using a list instead of a vector for the C++ version.

Well, it's even slower:

$ time slice4

real    0m4.500s
user    0m0.015s
sys     0m0.015s


Time of execution of vector version (using reference to a vector):

$ time slice2

real    0m2.420s
user    0m0.015s
sys     0m0.015s

Still slower than Python!


Source, using lists in C++:

---- slice4.c++ ----
#include <list>
#include <iostream>
#include <string>

using namespace std;

list<string> move_slice(list<string>& slist, int start, int stop, int dest)
{
	int idx;
	if( dest > stop)
		idx = dest - (stop - start);
	else
		idx = dest;
	
	list<string> frag;
	
	int i;
	list<string>::iterator startiter;
	list<string>::iterator enditer;
		
	startiter = slist.begin();

	for (i = 0; i < start; i++)
		startiter++;
	enditer = startiter;
	
	// copy fragment
	for (i = start; i < stop; i++)
	{
		frag.push_back(*enditer);
		enditer++;
	}	
	
	// delete frag from the slist
	slist.erase( startiter, enditer );
	
	// insert frag into slist at idx
	startiter = slist.begin();
	for (i = 0; i < idx; i++)
		startiter++;
	slist.insert( startiter, frag.begin(), frag.end());
	
/*	cout << "frag " << endl;
	for (startiter = frag.begin(); startiter != frag.end(); startiter ++)
		cout << *startiter << " ";
	cout << endl;
	
	cout << "slist " << endl;
	for (startiter = slist.begin(); startiter != slist.end(); startiter++)
		cout << *startiter << " ";
	cout << endl;*/
	
	return slist;
}
	

int main(int argc, char* argv)
{
	list<string> slice;
	string u = "abcdefghij";
	int pos;
	for (pos = 0; pos < u.length(); pos++)
		slice.push_back(u.substr(pos,1));
	int i;
	for (i = 0; i<1000000; i++)
		move_slice(slice, 6, 7, 7);

}

--------------------


Source, using reference to a vector:

---- slice2.c++ ----
#include <vector>
#include <iostream>
#include <string>

using namespace std;

vector<string> move_slice(vector<string>& vec, int start, int stop, int 
dest)
{
	int idx = stop - start;
	vector<string> frag;
	for (idx = start; idx < stop; idx++)
		frag.push_back(vec.at(idx));
	if( dest > stop)
		idx = dest - (stop - start);
	else
		idx = dest;
	vec.erase( vec.begin() + start, vec.begin() + stop);
	vec.insert( vec.begin() + idx, frag.begin(), frag.end());
	return vec;
}
	

int main(int argc, char* argv)
{
	vector<string> slice;
	string u = "abcdefghij";
	int pos;
	for (pos = 0; pos < u.length(); pos++)
		slice.push_back(u.substr(pos,1));
	int i;
	for (i = 0; i<1000000; i++)
		move_slice(slice, 6, 7, 7);

}

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