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Oct 10th, 2003

read to end of line problem

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I have no clue why this isn't working! Basically, I've got my tree and
everything working, but now I need to fit it to the input the instructor
gave me. What I need to do is read the first part of a line and then
input each following term into the tree... My problem come with reading
until the end of the line. For some reason, it won't recognise the newline
'\n' character. Right now I'm using strings but I've created a little
sample program below that shows what I'm talking about:

my input looks like this:
I1 kim abelo xxxx abcd xxxy
I2 abelo timmy
D1 kim abelo
D2 timmy
T1
T2
ID
IS

What I'm thinking this code should do is print out that first line only
but it keeps going.

C Syntax (Toggle Plain Text)
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
 
int main () {
  char temp;
 
  ifstream infile("in.txt");
 
  infile >> temp;
  while ((!infile.eof()) && (temp != '\n')) {
    cout << temp;
    infile >> temp;
  }
 
  cout << endl;
 
  return 0;
}
#include <iostream>
#include <fstream>
#include <string>
using namespace std;

int main () {
  char temp;

  ifstream infile("in.txt");

  infile >> temp;
  while ((!infile.eof()) && (temp != '\n')) {
    cout << temp;
    infile >> temp;
  }
  
  cout << endl;

  return 0;
}

output received:
I1kimabeloxxxxabcdxxxyI2abelotimmyD1kimabeloD2timmyT1T2IDIS

Thanks in advance.

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one1082

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Solved Threads: 0

Newbie Poster

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2 posts
since Oct 2003

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Oct 10th, 2003

Re: read to end of line problem

Why not use fgetc? I don't really use C++ constructs, so in C it would be (and I'm just writing this on the fly so expect some errors):

#include <stdio.h>
#include <stdlib.h>

int main() {

char myChar;
FILE *in = fopen("myfile.txt", "r"); // Open myfile.txt read-only
while((myChar=fgetc(in)) != EOF) {
if(myChar=='\n') printf("\n");
else printf("%c",myChar);
}
return 0;
}

File: myfile.txt

C Syntax (Toggle Plain Text)

this is
data
hehe

%./a.out
this is
data
hehe

If you want to break after the first line:

#include <stdio.h>
#include <stdlib.h>

int main() {

char myChar;
FILE *in = fopen("myfile.txt", "r"); // Open myfile.txt read-only
while((myChar=fgetc(in)) != EOF) {
if(myChar=='\n') {
printf("\n");
break;
} else printf("%c",myChar);
}
return 0;
}

Last edited by subtronic; Oct 10th, 2003 at 7:02 pm.

subtronic

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Solved Threads: 1

Junior Poster

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117 posts
since Aug 2003

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Oct 10th, 2003

Re: read to end of line problem

Replace

C Syntax (Toggle Plain Text)

infile >> temp;

with

C Syntax (Toggle Plain Text)
temp = infile.get() ;
temp = infile.get() ;

That should do the trick.

Dante Shamest

Reputation Points: 13

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Light Poster

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46 posts
since Apr 2003

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Oct 11th, 2003

Re: read to end of line problem

temp = infile.get() works perfectly. Thanks a ton. If you don't mind though could you explain the difference? I don't understand why one works and one doesn't. I appreciate it.

Tim

one1082

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since Oct 2003

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Mar 25th, 2008

Re: read to end of line problem

The reason that
temp = infile.get()
works and
infile >> temp
does not is because the >> operator ignores whitespace and new lines. get() reads in every character, no matter what

kwvanderlinde

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since Mar 2008

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Mar 29th, 2008

Re: read to end of line problem

Thank the gods.

Someone finally answered this question that we've all been struggling with this for 4 1/2 long years,

what a relief.

someone let Tim know he can mark this as "solved"

jephthah

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Posting Maven

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This thread is more than three months old

No one has posted to this discussion for at least three months. Please let old threads die and do not reply to them unless you feel you have something new and valuable to contribute that absolutely must be added to make the discussion complete. Otherwise, please start a new thread in this forum instead.

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