Resetting a ifstream object after reading the whole file

This is a discussion on Resetting a ifstream object after reading the whole file within the C++ Programming forums, part of the General Programming Boards category; Hi, I am reading a simple text file as following: Code: ifstream infile("doc.kml"); string line; while (infile >> line) { ...

  1. #1
    Registered User Zeeshan's Avatar
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    Lightbulb Resetting a ifstream object after reading the whole file

    Hi,

    I am reading a simple text file as following:
    Code:
        ifstream infile("doc.kml");
        string line;
    
        while (infile >> line) {
    ........
    ........
    .......
    ......
    ........
      }
    So, after reading past the complete file; I now want to reset the ifstream object (here infile). So, that I can again start reading the file from the first line in the next part of the code. Can somebody please tell me how to do this?

    I know, I could just close the file and open it back again, but isn't there some more straightforward method for this?

    Thanks a lot in advance.

  2. #2
    Registered User whiteflags's Avatar
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    Reset infile's get pointer to the origin of the stream with seekg(). I'm fairly certain the origin is zero, but look up seekg() in a C++ reference of some sort to be sure. It ought to tell you what to do.

  3. #3
    Registered User Zeeshan's Avatar
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    Thanks...what you say is also mentioned in the Reference...still Dev-C++ doesn't seem to do anything with this command!

    Anyways, thanks. I'll try this with some other compiler in university tomorrow.

  4. #4
    The larch
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    You might also need to clear() the eof state.

    However, wouldn't it be possible to store the contents of the file in memory, rather than reading it many times over?
    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
    Registered User
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    You're in luck I just recently had to solve the same darn problem myself. Here's what seemed to work for me:
    gfile is of type ifstream
    Code:
    		cerr << "Warning end of " << ifile << " reached" << endl ;
    		gfile.clear() ;
    		gfile.seekg(0, ios::beg) ;

  6. #6
    Registered User Zeeshan's Avatar
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    Thanks a lot SevenThunders and anon.

    It works now.

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