strange file opening problem

This is a discussion on strange file opening problem within the C++ Programming forums, part of the General Programming Boards category; I am trying to use a file stream to count some data. The odd thing is the second time I ...

  1. #1
    Registered User
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    May 2006
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    89

    strange file opening problem

    I am trying to use a file stream to count some data. The odd thing is the second time I use the ifstream, the file opens but it doesnt seem to read any data at all. Here is the code from the working portion:

    Code:
    ifstream infile;
    ofstream outfile;
    infile.open("08_28_06.txt");
    
    while(getline(infile, line)){
             string cat = line.substr(48, 3);
            if(cat == "HHD" || cat == "TLT")
               hhd++;
            else if(cat == "BAK")
                 bak++;
            else if(cat == "BEV")
                 bev++;
            else if(cat == "BXB")
                 bxb++;
            else if(cat == "CND")
                 cnd++;
            else if(cat == "CNJ")
                 cnj++;
            else if(cat == "CON")
                 con++;
            else if(cat == "HAB" || cat == "MED")
                 haba++;
            else if(cat == "RFR")
                 rfr++;
            else if(cat == "SNK")
                 snk++;
            else if(cat == "STA")
                 sta++;
            else if(cat == "SNA")
                 sna++;
            else
                misc++;
        }
        infile.close();
    And here is the non-working part:
    Code:
    line = "";
        infile.open("NEW_BAK.csv");
        bak = 0;
        while(getline(infile, line)){
            if(isdigit(line[0]))
             bak++;
        }
        cout << "BAK: " << bak << endl;
        infile.close();
    I tried putting the statement: if(infile.is_open()) cout << "open"; before the loop and it works, so the file is opened... but it never enters the loop and there IS stuff in the file.

    thanks

  2. #2
    Code Goddess Prelude's Avatar
    Join Date
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    Posts
    9,796
    Closing a stream does not reset the error flags. In this case, eofbit remains set despite closing the file and opening another with the same stream object. Try this:
    Code:
    infile.clear();
    infile.open("NEW_BAK.csv");
    My best code is written with the delete key.

  3. #3
    and the hat of wrongness Salem's Avatar
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    infile.clear();
    IIRC, the end of file doesn't go away when you just close the file and reopen it.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

  4. #4
    Registered User
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    May 2006
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    89
    thanks! I didn't know that and was completely stumped.

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