update line in text file

TheBT

Hi, I'm quite new to php so I need a little bit of help from you experts!
I need to edit a text file which stores userid and passwords.
Here is an example of the file:

1109::password::20101231::/members
2120::password::20101231::/members
5115::password::20101231::/members

So the first is the login, second part is password, third is the expiry date and fourth is the path.
Now what I want to make is a php script so the user can change his password.
So first I would need to lookup the line with his login and pass, if that's correct the user can type his new password. But the problem I have is how can I just change one word from a txt file? I looked a bit around, isn't there a php function that can do this?

Thanks

trexx

you should first read the file with file [http://www.php.net/manual/de/function.file.php]. you'll have each line in an array-element then.

loop through the array.
split each line with explode [http://www.php.net/manual/de/function.explode.php]
check if the username is in the line.
replace the password if you've found the right user.
implode the line again and write it to an output-string.
write the output string to the file

TheBT

Ok I did what you told me, I read the file:
$fp = file('pwd.dat');

Now I have an array with al the lines in it.
To split one line with explode I did:

$data = $fp[15];
list($user,$pass,$exp,$path) = explode("::",$data);

Now the problem is that I just split line 15. Because I can only split one line.

Something else I looked at was the command preg_match:

if (preg_match ("/\bUSERNAME\b/", "$fp[15]")) {
print "Found match with login ".$user." and pass ".$pass;
} else {
print "Nothing found.";
}

Now if I would want to change the pass I use the implode:

$pass = "newpassword";
$array = array($user,$pass,$exp,$path);
$out = implode("::", $array);

No how can I write that line back to that certain line in the file? Do I first need to read the whole file? Any examples on the web?

Thank you

xblue

if you've got a chance to do so, I'd strongly recommend to use a database, would be so much easier to handle tasks like this.

anyway:
- if you want to explode all lines rather than a specific one, you need to do it in a loop (e.g. a for or foreach loop).
http://www.php.net/manual/en/control-structures.php

there's no way to write to a specific line, so you'd probably modify whatever you want within the array returned from file(), then implode it into a string again, open the file for writing and write the complete content to it.

www.php.net/implode
www.php.net/fopen
www.php.net/fwrite
www.php.net/fclose

TheBT

Ok, it's working! 🙂

Thanks for your help!!

But only one small problem, when I want to write back to the file I just use the fwrite command. But the problem is that there is always a blank line between each data line. But when I output it to the screen and have a look at the source it's ok!
What can I do against it?

Thanks

xblue

explode() doesn't remove line breaks.
so when using something like implode("\n", $array) you'd double them.
implode('', $array) should be what you want.

hope this solves it 🙂