Test if std::vector<> contains a specific entry

How do I test to see whether or not a vector contains a specific entry? I've looked all over the MSDN doc on std::vector and I don't see anything.

For example:

std::vector<int> myVector;
myVector.push_back(10);
myVector.push_back(20);
myVector.push_back(30);

Aside from looping through the vector manually, what do I do to determine if the vector contains the value 20?

Thanks

Quote:

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Originally posted by SteveS
How do I test to see whether or not a vector contains a specific entry? I've looked all over the MSDN doc on std::vector and I don't see anything.

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That is because what you are looking for is an STL algorithm that works for many different containers, not just vector.

Use the std::find() algorithm. Note that std::find also works on plain old arrays too.

Code:

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#include <vector>
#include <iostream>
#include <algorithm>

int main()
{
    std::vector<int> myVector;
    myVector.push_back(10);
    myVector.push_back(20);
    myVector.push_back(30);
 
    std::vector<int>::iterator it = std::find( myVector.begin(), myVector.end(), 20 );
    if ( it != myVector.end() )
    {
          std::cout << "Found the element at position " <<
                    std::distance( myVector.begin(), it ) << std::endl;

          std::cout << *it;
    }
}

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Regards,

Paul McKenzie

Beautiful!

Works perfectly! Thanks a lot!
I have a list of C++ related books that I'm working through and STL is one of them. I think I'll put that one higher in the priority!

Thanks

Note that if the data is sorted it can be searched more efficiently. For small amounts of data it is efficient to search sequentially but for a large amount of data it could be quite significantly better if the search is not sequential.

To add to Sam's post, if your data is sorted, you can use the binary_search() algorithm function.

Regards,

Paul McKenzie