Search() algorythm

This is a discussion on Search() algorythm within the C++ Programming forums, part of the General Programming Boards category; I'm trying to use the algorithm Search() with strings. I get an error at the line where i marked. Could ...

  1. #1
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    Search() algorythm

    I'm trying to use the algorithm Search() with strings.
    I get an error at the line where i marked.
    Could somebody please give me a hint what am i doing wrong? Thanks in advance!

    Code:
    int main () {
      vector<string> myvector ;
      vector<int>::iterator it;
      
      string str = "search";
      string match = "ea";
      myvector.push_back(str);
      
      it = search (myvector.begin(), myvector.end(), match.begin(), match.end());   // error
    
      if (it != myvector.end())
        cout << "Match found at position: " << int(it - myvector.begin()) << endl;
      else
        cout << "Match not found." << endl;
      
      system("pause");
      return 0;
    }
    Sorry for the typo: algorithm.
    Last edited by Ducky; 01-18-2008 at 01:08 PM.

  2. #2
    The larch
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    It appears that you are trying to compare single characters (what string iterators point to) with whole strings (what vector<string> iterator points to), and eventually assign the result to a vector<int> iterator?!

    If you just want to find a substring in a string, then string has the find method.
    I might be wrong.

    Thank you, anon. You sure know how to recognize different types of trees from quite a long way away.
    Quoted more than 1000 times (I hope).

  3. #3
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    Thank you, i'm gonna check it if i can do it with find().

  4. #4
    The larch
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    Just out of interest, what would you have expected the output of your program to be?
    I might be wrong.

    Thank you, anon. You sure know how to recognize different types of trees from quite a long way away.
    Quoted more than 1000 times (I hope).

  5. #5
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    I would have expected something like: "Match found at position: 1" .

    So if i understand you well we should always compare the same types in C++.
    So maybe i should compare the first element of the vector to a string.
    Like this
    search (myvector[0].begin(), myvector[0].end(), match.begin(), match.end());
    Last edited by Ducky; 01-18-2008 at 12:22 PM.

  6. #6
    C++ Witch laserlight's Avatar
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    So, have you worked out a solution?
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  7. #7
    The larch
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    Like this
    search (myvector[0].begin(), myvector[0].end(), match.begin(), match.end());
    That looks more like it.

    However, if you only want to find a string in another string there may be easier ways: string reference
    I might be wrong.

    Thank you, anon. You sure know how to recognize different types of trees from quite a long way away.
    Quoted more than 1000 times (I hope).

  8. #8
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    Well for my final program i think im gonna use find() because it indeed does sound easier.

    For this specific program i dont understand why cant i assign search() to the iterator::it,
    when: "search() returns an iterator to the beginning of that matching subrange" .
    Last edited by Ducky; 01-18-2008 at 12:49 PM.

  9. #9
    The larch
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    Is it still an iterator of vector<int>? Since you search in a string, the result of search can only be assigned to string::iterator.
    I might be wrong.

    Thank you, anon. You sure know how to recognize different types of trees from quite a long way away.
    Quoted more than 1000 times (I hope).

  10. #10
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    Hmm thanks, i thought an iterator is always an int because its a number.
    I've changed the program but still get the error.
    Code:
    int main () {
      vector<string> myvector ;
      vector<string>::iterator it;
      
      string str = "search";
      string match = "ea";
      myvector.push_back(str);
      
      it = search (myvector[0].begin(), myvector[0].end(), match.begin(), match.end());   // error
    
      if (it != myvector[0].end())
        cout << "Match found at position: " << int(it - myvector[0].begin()) << endl;
      else
        cout << "Match not found." << endl;
      
      system("pause");
      return 0;
    }

  11. #11
    Registered User t3chn0n3rd's Avatar
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    C++ text book

    if you have an old college text book.

    they might have a bubble sort sample

  12. #12
    Algorithm Dissector iMalc's Avatar
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    Quote Originally Posted by Ducky View Post
    Hmm thanks, i thought an iterator is always an int because its a number.
    An iterator is never just a number or an int. It is usually contains a pointer, and possibly has other members as well.
    My homepage
    Advice: Take only as directed - If symptoms persist, please see your debugger

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  13. #13
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    @t3chn0n3rd bubble sort sample That rings me a bell, gotta look it up.

    @iMalc sounds like iterator is a complicated thing.

  14. #14
    C++ Witch laserlight's Avatar
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    bubble sort sample That rings me a bell, gotta look it up.
    Go ahead and look it up to refresh your knowledge, but in this case I do not think it applies. If it did, you should use something like std::sort() from <algorithm> instead of implementing bubble sort.

    sounds like iterator is a complicated thing.
    It can be complicated, or it can be as simple as a pointer, since pointers are iterators.
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  15. #15
    The larch
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    You are searching a string, not a vector. The string just happens to be put into a vector in this case (don't know why you need it there). Therefore the result needs to go to a string::iterator, not a vector<string>::iterator.
    I might be wrong.

    Thank you, anon. You sure know how to recognize different types of trees from quite a long way away.
    Quoted more than 1000 times (I hope).

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