eof problem c++

Question

i am using Dev C++ on windows xp

#include <iostream>
#include <fstream>
#include <string>
using namespace std;

int main ()
{
    string STRING;
    ifstream infile;
    infile.open ("sample.txt");
        while(!infile.eof)
        {
            getline(infile,STRING); 
            cout<<STRING; 
        }
    infile.close();

    return 0;
}

this codes gives the following error

C:\C++\read.cpp: In function `int main()':

C:\C++\read.cpp:11: error: could not convert `infile.std::basic_ios<_CharT, _Traits>::eof [with _CharT = char, _Traits = std::char_traits<char>]' to `bool'
C:\C++\read.cpp:11: error: in argument to unary !

i am not sure what is wrong here i cant compile the code please help

Not directly related to your question, but Dev-C++ is really outdated. Try using [Code::Blocks](http://www.codeblocks.org/downloads/26) with MingW or [Visual Studio Express](http://www.microsoft.com/express/Downloads/#2010-Visual-CPP) instead — Firas Assaad, Apr 23 '11 at 14:06
thanks for the suggestion @ Firas Assaad , i have used visual studio express , but its slows down my poor pc, i will try code::blocks — user721776, Apr 23 '11 at 14:15

Oswald · Answer 1 · 2011-04-23T16:08:47.777

10

std::ifstream::eof is a function that returns a bool. Thsu you have to call it like

infile.eof()

edited Apr 23 '11 at 16:08

answered Apr 23 '11 at 14:01

Oswald

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Please don't suggest using `.eof()` as a loop condition. It is almost always incorrect. – CB Bailey Apr 23 '11 at 14:26

score 10 · Accepted Answer · edited May 23 '17 at 12:03

10

If you change your loop to

  while(getline(infile,STRING))
  {
     cout<<STRING; 
  }

you avoid the possibility of reading the last value twice (see this SO post).

edited May 23 '17 at 12:03

Community

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1

answered Apr 23 '11 at 14:07

jonsca

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what if i use get() to read single char like infile.get() , then how do i control the loop without using infile.eof() ? – user721776 Apr 23 '11 at 14:38
@user721776: So long as you assign the result to an `int` (`std::istream::int_type`) and not a `char` (`std::istream::char_type`) then on all reasonable platforms you can reliably test against `EOF` (`std::istream::traits_type::eof()`) as your loop condition. – CB Bailey Apr 23 '11 at 14:48
@user721776 infile.get() with no arguments returns an int that you can test against *the value* EOF. In contrast, `infile.get(c)` where c is a character returns an istream object that you can check to see if it's null in the while loop condition just like with getline. – jonsca Apr 23 '11 at 14:49

score 8 · Answer 3 · answered Apr 23 '11 at 14:01

8

You forgot the () after the eof.

answered Apr 23 '11 at 14:01

wheaties

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eof problem c++

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