Message-ID: <19980115150953.17244.qmail@hotmail.com>
From: "Trond Endrestol" <endrestol AT hotmail DOT com>
To: naga4321 AT delanet DOT com
Cc: djgpp AT delorie DOT com
Subject: Re: Getline help
Content-Type: text/plain
Date: Thu, 15 Jan 1998 16:09:39 CET
Precedence: bulk

Hi!

In your program you use a couple of pointers that isn't properly 
initialized.

You must allocate memory for these pointers (look at the code at the 
bottom of this message).
getline() writes to a buffer you must provide a pointer to.

However this is a common mistake by new programmers.
(I have also made one of these.)

Using a pointer with out initializing it first can produce nasty results 
such as the computer locking up and you need to reboot.

Sincerely yours,
Trond Endrestøl.


My proposal for your code:

#include <fstream.h>

int main()
{

ifstream inFile = "test3.dat"; // test3.dat contains 2 lines for input

if (!inFile) {
  cerr << "Error occured during opening of file test3.dat.\n";
  return 1;
  }

// allocate memory using the new operator:
char *ptr_line1 = new char[51];
char *ptr_line2 = new char[51];

inFile.getline(ptr_line1,50,'\n'); 
inFile.getline(ptr_line2,50,'\n');   

cout << ptr_line1 << endl;
cout << ptr_line2 << endl; 

// return allocated memory, although we are just about to exit:
delete[] ptr_line1;
delete[] ptr_line2;

// close inFile:
inFile.close();

return 0;
}


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