simultaneous iteration over several vectors

[yotama9]

Hi guys.

Is there a way to iterate simultaneously over two or more vector in c++?
The only thing I could think of is creating a loop and incrementing the iterator for all of them or using the [] operator which is slower.

Thanks.

[LB]

Here's how I might do it:

vector<int> VectorA;
//stuff


vector<long> VectorB;
//stuff

vector<int>::iterator ItA = VectorA.begin();
vector<long>::iterator ItB = VectorB.begin();
while(true)
{
	//
	//do stuff with ItA and ItB
	//

	if(ItA != VectorA.end())
	{
		++ItA;
	}
	if(ItB != VectorB.end())
	{
		++ItB;
	}
	if(ItA == VectorA.end() && ItB == VectorB.end())
	{
		break;
	}
}

[Galik]

vector v, w;
iterator i, j;

for(i(v.begin()), j(w.begin()); i != v.end() && j != w.end(); ++i, ++j)
{
    // do stuff
}

[jsmith]

NOTE: operator[] on vectors is not necessarily slower than iterators. However, iterators are a more general solution.

As a second observation, consider whether or not you can combine the vectors into a single vector of structs.

ie,

std::vector<int> intVec;
std::vector<long> longVec;

// becomes:

struct MyStruct
{
    int anInt;
    long aLong;
};

std::vector<MyStruct> vec;