re-ordering a text file

optional

Can someone please help me with a suggestion on the best way to read a text file, randomly re-order the lines, then re-write the file.

I'm a newb and have played around enough to get it half working. It writes the file but the script never completes and evenutually gives the error
Fatal error: Maximum execution time of 30 seconds exceeded in test.php on line 7

$contents = file("database.txt");
shuffle($contents);
$handle = fopen ("database.txt", "w+");
$data = explode("\n", $contents[$i]);
for($i=0; ; $i++) {
$data = $contents[$i];
fwrite ($handle, $data);
}
fclose ($handle);

2 issues I am not sure about.. 1. what to use in the 2nd parameter of the for line to make it stop looping when it gets to the end of the file... and 2. should I be exploding on \n to do this like I am? and if so how can I make it work if supplied with a file that doesnt have a \n at the end of the last line.

Thanks in advance for any help or suggestions on a beter way to do this.

lazzerous

ok... lets go through this:

// grab the contents of database.txt and load them into var $contents
$contents = file("database.txt"); 

// shuffle the contents of $contents
shuffle($contents); 

// open database.txt for writing
$handle = fopen ("database.txt", "w+"); 

// write the shuffled contents of $content to $handle
fwrite ($handle, $contents); 

// close the newly over-written file
fclose ($handle);

make sense? I'm not even sure if I did this right... heh

optional

Originally posted by lazzerous
// write the shuffled contents of $content to $handle
fwrite ($handle, $contents);

Thanks lazzerous but the above line wont work becasue the shuffle($contents) command doesnt return anything... it just resorts the data ready to be output... thats why I tried to use this bit....
$data = explode("\n", $contents[$i]);
for($i=0; ; $i++) {
$data = $contents[$i];
fwrite ($handle, $data);
}

to write it back to the new file line by line...

I dont think I have that part correct though as it doesnt seem to stop looping at the end of the file... and I was hoping someone might know a more efficient way to go about this as well.

Strings

It looks like you have an infinite loop on your for loop. You haven't given it a condition when to stop so it keeps on going. Try this for the for loop:

for($i=0;$i<=count($data);$i++)

optional

Originally posted by Strings
It looks like you have an infinite loop on your for loop. You haven't given it a condition when to stop so it keeps on going. Try this for the for loop:
for($i=0;$i<=count($data);$i++)
[/B]

awesome.. thankyou Strings, that is just what i was looking for... just had no idea how to word the condition ;-)

It didn't work using count($data) though... only returned the first two lines in the file... but it did work exactly as hoped when I used count($content)

<?php
$contents = file("database.txt");
shuffle($contents);
$handle = fopen ('database.txt', 'w+');
$data = explode("\n", $contents[$i]);
for($i=0;$i<=count($contents);$i++) {
$data = $contents[$i];
fwrite ($handle, $data);
}
fclose ($handle);
?>

Do you have any idea about the best way to deal with a database.txt file that doesnt have a \n at the end of the last line? Do I need to check for it and add one myself to be safe or does PHP have some inbuilt function to deal with this does anyone know?

Weedpacket

lazzerous's code was missing one tiny detail, which becomes clear when one looks at what it's doing.

// write the shuffled contents of $content to $handle
// Don't forget that $contents is an array
// and fwrite() expects a string!
fwrite ($handle, join('', $contents));

optional

Now that's SEXY.... thanks Weedpacket 🙂

<?php
$contents = file("database.txt");
shuffle($contents);
$handle = fopen ("database.txt", "w+");
fwrite ($handle, join('', $contents));
fclose ($handle);
?>

optional

I've had a look at the manual about join and impode and I cant work out why this works.

join('', $contents)

why does join with an empty glue string work?

bubblenut

It literally joins every element of the array together with nothing in between.

$var2=implode('',$var1);

would give the same result as

$var2='';
foreach($var1 as $data)
  $var2.=$data;

HTH
Bubble

optional

Ah.. thankyou, I get it 🙂

so simple when the obvious is pointed out... I already had a \n between each element so I could just slam the lot back together!!

thanks again everyone that posted...

I'm surprised how much I have managed to achieve with such a small amount of knowledge.... and a little help 😉

heisje

thanks to the good people who have provided this elegant solution.
and now I humbly submit a further request for a similar application:

how can this script (suggested above):

<?php
$contents = file("database.txt");
shuffle($contents);
$handle = fopen ("database.txt", "w+");
fwrite ($handle, join('', $contents));
fclose ($handle);
?>

be modified to process a text (i.e. shuffle it line by line, as above) residing within the php page itself (or within the php script itself) - and not a text imported from an external file (database.txt) ?

especially if the "text" is html?
for example a number of lines such as:

<p><a href="http://mydomain.com/index.html">Hello World</a></p>

many thanks for any ideas!!

best,
heisje

optional

This might do what you want... but someone with more expertise than me might know a better way.

<?php
$contents = array('<p><a href="http://mydomain.com/index.html">Hello World</a></p>','<p><a href="http://mydomain.com/index2.html">Hello World 2</a></p>','<p><a href="http://mydomain.com/index3.html">Hello World 3</a></p>'); 
shuffle($contents); 
foreach ($contents as $value) {
   echo $value;
}
?>

heisje

hi optional,

many thanks for taking the time of looking into this, it was much appreciated!
it certainly WORKS !

a very simple solution (many times the simpler solutions are the more elegant), which resolves totally my current problem, and I am very happy with it.

however, as this needs to have already the text in an array form exactly, I would like to take this a step further, if at all posssible:
if any html text/code, already in lines, was to be re-shuffled line by line, but which was not already in an array form, meaning:

not already available like this:

'<p><a href="http://mydomain.com/index.html">Hello World</a></p>',
'<p><a href="http://mydomain.com/index2.html">Hello World 2</a></p>',
'<p><a href="http://mydomain.com/index3.html">Hello World 3</a></p>',

but available like this:

<p><a href="http://mydomain.com/index.html">Hello World</a></p>
<p><a href="http://mydomain.com/index2.html">Hello World 2</a></p>
<p><a href="http://mydomain.com/index3.html">Hello World 3</a></p>

so:
how would any html text/code in lines, as above, already residing within the script,
ex:

$contents = "
<p><a href=http://mydomain.com/index.html>Hello World</a></p>
<p><a href=http://mydomain.com/index2.html>Hello World 2</a></p>
<p><a href=http://mydomain.com/index3.html>Hello World 3</a></p>
"

or ex:

$contents = "
<p><a href="http://mydomain.com/index.html">Hello World</a></p>
<p><a href="http://mydomain.com/index2.html">Hello World 2</a></p>
<p><a href="http://mydomain.com/index3.html">Hello World 3</a></p>
"

be processed into a proper array and then shuffled line by line??
I was trying hard going the way of "explode" but with no success, apparently doing something very wrong.

many thanks for any ideas on this!

best,
heisje

heisje

while the following scripts work, for shuffling text/code in lines, line by line:

<?
$html= '<p><a href="http://mydomain.com/index.html">Hello World</a></p>
<p><a href="http://mydomain.com/index2.html">Hello World 2</a></p>
<p><a href="http://mydomain.com/index3.html">Hello World 3</a></p>';

$newhtml = explode("\n", $html);
shuffle($newhtml);
foreach($newhtml as $line) {
       echo $line . ' ';
}

?>

and a variation of the above:

<?
$html= '<a href="http://mydomain.com/index.html">Hello World</a>
<a href="http://mydomain.com/index2.html">Hello World 2</a>
<a href="http://mydomain.com/index3.html">Hello World 3</a>';

$newhtml = explode("\n", $html);
shuffle($newhtml);
foreach($newhtml as $line) {
       echo $line . '<br>';
}

?>

and another variation of the above:

<?
$text= 'Hello World
Hello World 2
Hello World 3';

$newtext = explode("\n", $text);
shuffle($newtext);
foreach($newtext as $line) {
       echo $line . '<br>';
}

?>

QUESTION: what has to be changed in this, in order to avoid problems when text contains various signs like " ' " or ";" etc?

if the text/code is introduced from an external file, like ex:

$text=file("external.txt");

there are no problems, even if signs are present in the external file.

but if the text/html code is directly written within the script and contains such signs, the script, of course, will not function.

any ideas?

best,
heisje