Vector Iterator Problem

[joatmon]

Having trouble iterating through a vector in a function:

int main()
{
   ...
   vector<int> customer;
   vector<int> switch_tolerance;
   ...
}

bool is_switching(unsigned int this_second, unsigned int this_customer, const vector<int>& customer, const vector<int>& switch_tolerance)
{
    int n;
    vector<int>::iterator it;

    it = find(customer.begin(), customer.end(), this_customer);
    ...
}

The compiler errors out on my find call. Anyone see what is wrong?

Thanks.

[andywestken]

Remember to post the error next time!

But I can see that you're passing your vector by const ref :-)

you need to use a const_iterator

vector<int>::const_iterator it;

Andy

P.S. It would be better C++ style to use

vector<int>::const_iterator it = find(customer.begin(), customer.end(), this_customer);

In your case, the iterator's default constructor is called, and then its operator=

In the case I've just given, just the assignment constructor is triggered. (Class obj = val; and Class obj(val); are the same in this respect. The latter form is less readable in this case (for me) as the instance name is so much smaller than the find(..) expression.

[joatmon]

Thanks. I made that change, but it still errors out. I didn't post the error because it's very long and cryptic (to me, at least). Here it is, in all its glory:

main.cpp|213|error: no matching function for call to 'find(__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, unsigned int&)'|

Maybe this will make sense to you? Thanks for your help!

[andywestken]

Does casting this_customer to int fix the problem?

... = find(customer.begin(), customer.end(), (int)this_customer);

(if this works, should at least use a proper C++ cast)

If not, what standard headers are you including?

[joatmon]

I tried that, but it didn't change anything. Here are all my headers:

#include <iostream>
#include <cstdlib>
#include <deque>
#include <vector>
#include <ctime>

using namespace std;

Thanks again. I'm really stumped.

[DSLq5Di1]

Missing the algorithm header!

[joatmon]

Thanks. As a C++ beginner, how would I know to look for this? I looked at the iterator reference page on this site, and I see no mention of needing the algorithm header. This is the kind of stuff that makes me crazy about learning C++, so I'm obviously trying to make this process less frustrating.

Any advice is appreciated. Thanks again for catching that.

[andywestken]

<algorithm> is needed for std::find()

And all the other algorithic functions like find_if, sort, replace, remove, remove_if...

I use MSDN to check things stl related, but I'm a Windows programmer so I use that site as a matter of routine.

But sometimes I use SGI's site, as their stl was (is) one of the reference implementations: http://www.sgi.com/tech/stl/find.html

The error messages produced for template problems aren't as bad as they used to be, but they are rather arcane. But you soon learn to spot the key bits!

[joatmon]

Thanks for all the help!