question about getline function

Question

1.00/5 (2 votes)

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C++

#include <iostream.h>
#include <conio.h>
#include <fstream.h>
void main()
{
clrscr();
ifstream g;
char str[100];
g.open("a.txt");
while(str!='\n') problem is here
{
g.getline(str,20);
cout<<str;
}
g.close();
getch();
}

I read that getline functions reads a seqpence of character untill end of line is reached('\n')
but my program can not work

Posted 12-Jun-13 1:03am

ALIWAZ

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Comments

CHill60 12-Jun-13 7:30am

When you say "my program can not work" give us details of either the error message(s) you are getting or explain how the actual results differ from your expected results. Use the Improve question link above to update your post

2 solutions

Solution 2

I have modified your program for you, here is the code:

C++

#include <iostream>
#include <fstream>

using namespace std;

int main()
{

	ifstream g;

	char str[100];

	g.open("a.txt");

        /* repeat following actions 
           until end of file is reached */

	while( ! g.eof() ) 
	{
                /* clear our string, so we can get
                   new data */

		memset( &str, '\0', sizeof(str) );
		
                // get 100 characters into str
	
		g.getline(str,100);

                // write the result, and go to new line

		cout<<str<<endl;
		
	}

	g.close();

	return 0;
}

It has been a while since I have dealt with this, but I hope that this will help you.
Best regards and good luck!

Posted 12-Jun-13 17:10pm

MyOldAccount

Updated 12-Jun-13 17:14pm

v3

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Matthew Faithfull · Accepted Answer · 2013-06-12T01:35:00

Quote:
my program can not work

No it cannot.
There is never going to be a point where str a pointer to 100 chars is going to be equal to the constant value '\n' which if I remember correctly is evaluated as 13.
Your while loop will never complete. Your while loop is also possibly unnecessary if you only want to read one line but I don't know for sure what you're trying to do.

I would recommend you check your understanding of pointers. Many people find this a difficult topic in C/C++.