Need help to understand this statement

This is a discussion on Need help to understand this statement within the C++ Programming forums, part of the General Programming Boards category; Could someone please help explain it to me what does the following statement means? It will be best if you ...

  1. #1
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    Need help to understand this statement

    Could someone please help explain it to me what does the following statement means? It will be best if you could use some examples. Thanks

    An iterator can become invalid whenever a change is made to the underlying container.

  2. #2
    Registered User Noir's Avatar
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    Code:
    vector<int>::iterator i = v.begin();
    
    v.push_back( 20 );
    
    // i can't be used anymore
    
    i = v.begin();
    
    // now i can be used again
    An iterator is like a pointer into the container, but if you change the container and it moves things around internally so that the pointer doesn't point to where the item is, the iterator is invalid.

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    Thanks

  4. #4
    Cat without Hat CornedBee's Avatar
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    The statement is, without context, too general, though. Among the properties of the various containers is a description of when, exactly, iterators can become invalid.
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

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