Read file into variable

This is a discussion on Read file into variable within the C++ Programming forums, part of the General Programming Boards category; Hello, I started learning C++ yesterday and have been working through the tutorials. I have come to the part regarding ...

  1. #1
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    Read file into variable

    Hello,

    I started learning C++ yesterday and have been working through the tutorials. I have come to the part regarding File I/O and am a little stuck...

    Code:
     ifstream ifile("test.txt");
     ifile >> old_ans;
     ifile.close();
    
     cout << "File contents:\n\n" << old_ans;
    The above is a snippet from my code, the problem is cout'ing old_ans only outputs the first word from the file, how should i go about outputting the whole file contents?

    My previous experience is with PHP in which i would just use:

    Code:
    $var = file_get_contents('text.txt');
    etc
    But being a c++ newbie i am a little stuck on a simple problem.

    Thank you for any help or advice you can give me.

  2. #2
    Registered User Micko's Avatar
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    See if this can satisfy you
    Code:
    #include <cstdlib>
    #include <iostream>
    #include <fstream>
    
    using namespace std;
    
    int main()
    {
       ofstream o("test.txt");
       o<<"Test"<<endl<<"And more test"<<endl;
       o.close();
       
       ifstream in("test.txt");
       cout<<in.rdbuf();
       system("pause");
    }
    Gotta love the "please fix this for me, but I'm not going to tell you which functions we're allowed to use" posts.
    It's like teaching people to walk by first breaking their legs - muppet teachers! - Salem

  3. #3
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    Thank you Micko, that worked nicely

  4. #4
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    Hi,

    You need to know that the ">>" operator has a special method of reading input: it skips all leading whitespace(spaces, tabs, newlines) until it finds something to read, then it starts reading input, and then it stops reading input when it encounters any whitespace.

  5. #5
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    Thank you for the information 7stud, that explains the behaviour of my original code.

    On the bright side, a mistake made leads to a lesson learned.

  6. #6
    Registered User Micko's Avatar
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    If you don't screw up, you don't learn! Its just that simple!
    Gotta love the "please fix this for me, but I'm not going to tell you which functions we're allowed to use" posts.
    It's like teaching people to walk by first breaking their legs - muppet teachers! - Salem

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