🔒 Locked

Read Line into stringstream.rdbuf()

Started by Boder Apr 20, 2006 at 4:11 AM 1 reply 1.2k views

Original Post

Boder

180

Boder

Apr 20, 2006 at 4:11 AM

Why does the input fail when passing the string buffer of a string stream into the get() method for an ifstream?


#include <sstream>
#include <fstream>
#include <iostream>
#include <cassert>

using namespace std;

char const * const text =
"This text is const \n\nconst for you and const for me. \n\nDo you like const text? \n\nI do.\n";

int main()
{

 ofstream out("text.txt");
 out << text;
 out.close();

 ifstream in("text.txt");
 stringstream buffer;

 while( !in.eof() )
 {

  in.get( *buffer.rdbuf() );
  cout << buffer.str() << endl;
  assert( in.good() );

 }

 in.close();

}

Bregma

1,022

Bregma

Apr 20, 2006 at 7:52 AM

The std::istream.get() function does not consume the delimiter, so the next iteration through the loop it copies nothing from the input buffer to the output buffer. Not copying anything sets the input buffer into an error state.

The default delimiter is newline.

This is a pretty obscure function to use in application code. You may find there is a reason why you don't generally see it used.

Boder

Author

180

Boder

Apr 20, 2006 at 12:42 PM

I kind of got it to work. Thanks for the tip.

while( !in.eof() && in.good() ){ while( in.peek() == '\n' ) in.get(); in.get( *buffer.rdbuf() ); cout << buffer.str() << endl; buffer.str("");}

Topic Locked

This topic has been locked by a moderator. New replies are not allowed.