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Jul 8th, 2009

reread line using fstream getline

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Hi I got a code that in pseudo dos something like

C++ Syntax (Toggle Plain Text)
ifstream os;
while(os.oef()){
   os.getline(buffer,length);
}
ifstream os;
while(os.oef()){
   os.getline(buffer,length);
}

If some condition is met,
I'd like to be able to jump back to the previous line,
such that the next getline will give the line just-read in, at a later time in my execution timeline.

Is this possible?

thanks

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monkey_king

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Junior Poster

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since Aug 2008

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Jul 8th, 2009

Re: reread line using fstream getline

Read
tellg and seekg methods.

adatapost

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Posting Genius

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Jul 8th, 2009

Re: reread line using fstream getline

Use two buffers or even better two std::strings:

C++ Syntax (Toggle Plain Text)
ifstream os; // variable name misleading!
string prev, curr;
while(getline(os, curr))
{
   ...
   prev = curr;
}
ifstream os; // variable name misleading!
string prev, curr;
while(getline(os, curr))
{
   ...
   prev = curr;
}

Last edited by jencas; Jul 8th, 2009 at 8:04 am.

jencas

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Posting Whiz

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Jul 8th, 2009

Re: reread line using fstream getline

To the OP:
Don't write your code like this: while(os.eof()) , instead write it like jencas did.
Want to know why? Do a forum search on: feof or eof

Edit:: I thought it was safely to assume that the 'oef' in 'os.oef()' is a typo he made.
(Because AFAIK there is no such data member in the iostream class library)

Last edited by tux4life; Jul 8th, 2009 at 11:35 am.

tux4life

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Postaholic

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