Thread: Searching a vector/struct for strings?

Glauber, do you even have a compiler or anything like that?

A vector is supposed to model an array, which is simply a sequential collection of items.

So if you had various books and you'd want to find a particular one, you'd have to use a search algorithm. One of the posters showed you pseudo-code for the simplest algorithm, linear search. Just move through the collection one by one and compare the item to the search criterion. True, you might be comparing only part of the items to what you're looking for but you need to understand how to access info from the collection.

But the idea in arrays is that each item in the collection has a index so you can look it up again right away.

my_library[]:
Snow Crash
Neal Stephenson
----------------------
Inca Gold
Clive Cussler
----------------------
The Hitchhiker's Guide to the Galaxy
Douglas Adams
----------------------
The Rainmaker
John Grisham
-----------------------

The middle books, Inca Gold and Hitchhiker's Guide, are at indices 1 and 2 if we start from zero. So if you wanted to do something with a part of either of those books (or any book) you need to look it up. Then you can access the members of a book record, like the author name or title.

Now, in linear searching, you might stop the search on the first match, or keep searching through the whole space and return a collection of the matches (this works well for more relaxed search criteria, such as "every Stephen King novel here").


You really do need a book though. We are not a classroom!

Originally Posted by laserlight

Close, but not quite. The main problem is that the index i loops from 0 to one less the vector size. books.name does not exist, since vectors do not have a name member. A more minor problem is that the type of the index should be vector<data>::size_type, not int. Then, after you have found a matching element, you may wish to break out of the loop (or you may not, it depends). Consequently, a more likely solution would be:

Code:

vector<data> books;
// ...
cin >> search_input;

for (vector<data>::size_type i = 0; i < books.size(); ++i)
{
    if (books[i].name == search_input)
    {
        cout << "Found with title: " << books[i].title << endl;
        break;
    }
}

Thank you.