ifstream a string to the screen?

This is a discussion on ifstream a string to the screen? within the C++ Programming forums, part of the General Programming Boards category; Hi, I'm trying to input entire lines of text from an open file to the screen. So far, I've only ...

  1. #1
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    Dec 2001
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    ifstream a string to the screen?

    Hi,

    I'm trying to input entire lines of text from an open file to the screen. So far, I've only been able to print one word at a time followed by an unwanted newline. What's the secret? And, what recommendations can you give for a text that goes beyond the beginner material?

    Here are some snips:

    ifstream fin("dbase_a.txt", ios::in);
    while (fin >> line))
    {
    outputLine(line);
    }

    void outputLine(const string line)
    {
    cout << line << endl;
    }

    Thanks,
    David Korb

  2. #2
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    Allow me to follow this up by saying "Oops!". Okay, so my unwanted newline was right there in my code, but how do I reproduce the newline that is inherent in the file itself? It all runs together at this point:

    Smith,John:1208:Jan.31,1998Decker,Jane:8012ec.01,1997Mo,Joe:1028:Jan.12,198Rock,Dan:2081:June 01,1998Cahn,Debbie:2801:July16,1997Dusty,Tom:3012: July19,1998Harvey,Sheila:3141:Aug.021998Press any key to continue . . .

    This database was just something to work with. The file I really want to print out is going to be a normal text document.

  3. #3
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    You can use getline with an appropriate delimeter. The default is '\n' so it should work with what you need. The reason it doesn't work with operator>> of ifstream is that operator>> uses whitespace as a delimeter so you only get one word at a time.
    Code:
    #include <fstream>
    #include <iostream>
    #include <string>
    
    using namespace std;
    
    int main() {
        // ios::in is the default, so no need to specify it
        ifstream f("dbase_a.txt");
        string line;
        
        // getline eats the delimeter ('\n' by default) but doesn't
        // store it, so you'll have to consider that when using it.
        while(getline(f, line)) { 
            cout << line << endl;
        }
    }
    Hope this helps.
    - lmov

  4. #4
    _B-L-U-E_ Betazep's Avatar
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    Very nice use of comments and instruction, IMOV.

    We need more people like you.
    Blue

  5. #5
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    Cool

    Or you may use the get() function in the following way:


    void main()
    {
    ifstream fin("dbase_a.txt");
    char line; //change line to char type

    while (fin.get(line)) //use get() function
    {
    outputLine(line);
    }
    }

    void outputLine(const char line)
    {
    cout << line; //drop the endl escape-sequence
    }

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