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Old 05-14-2004, 02:05 AM   #1
lrt2003
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Registered: Mar 2004
Distribution: Fedora 10
Posts: 182

Rep: Reputation: 30
C++ reading from text file query


Hello there.

I have been following these tutorials:
http://www.cplusplus.com/doc/tutorial/tut6-1.html
http://cplus.about.com/library/weekly/aa022402a.htm

and did a bit of googling, but can't seem to find how to input from a text file and echo exactly what's in it (I can get it to echo without spaces, but that doesn't really help..)

here's what I'm using:

#include <iostream>
#include <fstream>
#include <string>
using namespace std;

#define welcomemsg "Welcome to my Message Keeper!"
string tx;

int main()
{
cout << welcomemsg << endl << "Enter the number of the message you wish to read then press enter." << endl;

ifstream msgList;
msgList.open("msglist.txt");

if (! msgList)
{
cout << "Error opening input file" << endl;
return -1;
}

while (msgList >> tx) {
cout << tx;
}

return 0;
}
---
(contents of msglist.txt is "Hello there!"

any help would be appreciated, I'm just starting!!
 
Old 05-14-2004, 05:29 AM   #2
arvind_sv
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Registered: Oct 2002
Location: Bangalore
Distribution: Gentoo Linux
Posts: 96

Rep: Reputation: 16
Hi,

Try something on these lines:

Code:
#include <iostream>
#include <fstream>
using namespace std;

int main()
{
    ifstream msgList;

    msgList.open("msglist.txt");
    if (!msgList)
    {
        return (1);
    }

    char tx[1000];
    while (msgList.getline (tx, 1000, EOF)) {
        cout << tx;
    }

    return 0;
}
Arvind

PS: You said you were starting out. First thing you should learn about is code indentation.
 
Old 05-14-2004, 08:32 AM   #3
lrt2003
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Registered: Mar 2004
Distribution: Fedora 10
Posts: 182

Original Poster
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that works, thanks a lot!

btw, I'm starting up a project for newbies to code this message keeper... where newbies can muck about and learn C++ and get a bit of experience (I'm a real newbie myself, as you can tell) - it's at http://www.geocities.com/latestringtones2003/
 
Old 05-14-2004, 11:29 AM   #4
arvind_sv
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Registered: Oct 2002
Location: Bangalore
Distribution: Gentoo Linux
Posts: 96

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Oh, if you were actually so serious about that, you might be better off with this:

Code:
    char tx[1000];
    while (msgList) {
        msgList.get (tx, 1000, EOF);
        cout << tx;
    }
Try the code I sent previously with size set to something like 10. Does it work?

If you want to never worry about buffer overflows and the like, then (as you had originally posted), use "string"s:

Code:
    string str;
    while (1) {
        getline (msgList, str);
        cout << str;
        // Print a newline only if it's not the last line.
        if (msgList) {
            cout << endl;
        }
        else {
            break;
        }
    }
Arvind
 
Old 05-14-2004, 08:23 PM   #5
lrt2003
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Registered: Mar 2004
Distribution: Fedora 10
Posts: 182

Original Poster
Rep: Reputation: 30
Oh, I don't want it exploitable.. I'm doing some research on buffer overflows now..

I'll change the code now, get and getline.. much to learn!

thanks for the help, you have a little mention on my site

Last edited by lrt2003; 05-14-2004 at 08:26 PM.
 
Old 05-15-2004, 04:25 AM   #6
arvind_sv
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Registered: Oct 2002
Location: Bangalore
Distribution: Gentoo Linux
Posts: 96

Rep: Reputation: 16
Ha ha! Very nice. Thanks. Let's see how your project develops.

Arvind
 
  


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