Help with a small assignment...

elmalote

I need to create a class (MySQL) with the following functionality

function_connectsql($host, $user, $password, $database);
function_getrecords($query);

returns an array() where:
array[0]= number of records
array[1] = number of fields
array[2] to array[n] = found data

function_query($query);
function_readfilebackwards($file,$lines);

This function should be able to read a ASCII text file backwards and return an array where the last line in the file becomes the first lines.

array[0] - last line in the file
array[1] - second last line in the file
$lines is used to narrow how many lines wished to be read, 0 = all lines
Line seperator is chr(10)

Now here is the tricky part, I'm not allowed to just read the file and reverse the array
So can anyone help me how to do it ?

Thanks a lot...

SargeZT

Well, made a reverse_text function for you. Not perfect, I'm not that great myself. I'm quite sure it could be done much more simply.

<?php
function read_file_backwards($file,$lines) {
  $ftext = file_get_contents($file) or die("Could not open file");
  $lb = chr(10);
  $lblist = array();
  $bwtext = array();
  $lblist[] = 0;
  $offset = 0;
  $len = strlen($ftext);
  while (strpos($ftext,$lb,$offset)) {
    $offset = (strpos($ftext,$lb,$offset)+1);
    $lblist[] = ($offset-1);
  }
  $lblist = array_reverse($lblist);
  if ($lines != 0) {
    $lblist = array_slice($lblist,0,$lines);
  }
  $key = 0;
  while ($key < count($lblist)) {
    $bwtext[] = substr($ftext,$lblist[$key],(-$lblist[$key] + ((($key-1)>=0) ? $lblist[($key-1)] : $len) ) + 1);
    ++$key;
  }
}
?>

I didn't know if you wanted the linebreaks trimmed or not. Just add an rtrim into the while loop if you do. The rest of the class should be a breeze, IMHO.

Edit - Realized I didn't explain how it works.

Searches for each occurence of the $lb char, and puts it into an array, along with a buffer 0 to make the script work. Then it simply uses substr() to extract each line. The math is pretty self explanator, with the exception of using the ternary operator. I used the ternary operator because the math wouldn't work on the first value, as -1 isn't a valid array index. Thus, I just use the length of the file.

Roger_Ramjet

What a dumb assignment: not allowed to do it the proper way with file() and reverse the array?? What are they trying to teach you? How to be a dumbass? Surely there are enough difficult things to do with PHP without inventing difficult ways to do easy things.

thorpe

on top of that... who is this dumbass (SargeZT) posting answers (if it works)?

if its an assignment... figure it out yourself. thats the point! what if you teacher asks how you came to this conclusion?

oh, oh.... my dog ate it

elmalote

SargeZT wrote:
Well, made a reverse_text function for you. Not perfect, I'm not that great myself. I'm quite sure it could be done much more simply.
<?php
function read_file_backwards($file,$lines) {
  $ftext = file_get_contents($file) or die("Could not open file");
  $lb = chr(10);
  $lblist = array();
  $bwtext = array();
  $lblist[] = 0;
  $offset = 0;
  $len = strlen($ftext);
  while (strpos($ftext,$lb,$offset)) {
    $offset = (strpos($ftext,$lb,$offset)+1);
    $lblist[] = ($offset-1);
  }
  $lblist = array_reverse($lblist);
  if ($lines != 0) {
    $lblist = array_slice($lblist,0,$lines);
  }
  $key = 0;
  while ($key < count($lblist)) {
    $bwtext[] = substr($ftext,$lblist[$key],(-$lblist[$key] + ((($key-1)>=0) ? $lblist[($key-1)] : $len) ) + 1);
    ++$key;
  }
}
?>
I didn't know if you wanted the linebreaks trimmed or not. Just add an rtrim into the while loop if you do. The rest of the class should be a breeze, IMHO.

Edit - Realized I didn't explain how it works.

Searches for each occurence of the $lb char, and puts it into an array, along with a buffer 0 to make the script work. Then it simply uses substr() to extract each line. The math is pretty self explanator, with the exception of using the ternary operator. I used the ternary operator because the math wouldn't work on the first value, as -1 isn't a valid array index. Thus, I just use the length of the file.

Thanks a lot 🙂

I'ma try this..
Thanks again, appreciate the help.

And to Thorpe:
Lay of the man, he is only helping, if you don't have any constructive to say on the topic, then don't bother posting.

Roger_Ramjet

Elmalote, it happens that every now and then, some programming class discovers this forum and then we get 15 people all posting problems to the same assignment. Now some people might say that it shows initiative if you can get others to do your work for you. Many of us, on the other hand, see it as a) cheating, and b) of no help to the students themselves cos they learn nothing.

dalecosp

And this is the point at which we point people to some of the important threads around here and repeat the mantra of Papa Weed's old .sig, "Give a man a fish ...."

😉

SargeZT

Sorry if I offended you Thorpe, but I most certainly would never hand that script in as an assignment. It's not horrible, but I'd certainly hope he'd improve it before he turns it in.

If not, I really don't care, but calling me a dumbass might not be the most effective way of working out your problems.

Dalecosp, you're quite right. I agree, I wasn't really planning to write the script, but it piqued my interest and I tried to figure out an eloquent way to do that. Whether I found that way is very much up for debate. Perhaps I shouldn't have done it, and I apologize. I'm not used to the customs of this forum, as can be seen by my post count.

Roger_Ramjet

Don't worry about it Sarge, we all start out trying to solve every problem. It's only after a while when you see the same problem turning up all at once like a rash that the penny drops. I'm sure that there are tutors out there who point their classes at this place and let us do their job for them.

elmalote

I'm not a PHP expert, I'm a Java expert, and the assignment is not for me, its for a friend. They gave this test to him as part of a job interview. So the moral preaching is not necessary. I wouldn't get someone to do it for me, specially not for a job interview.
But I was only trying to help him out...

SargeZT

Now for a job interview, the question is far from retarded. It demonstrates being able to think out of the box.

But I want the job. :/

_theworks

elmalote wrote:
I'm not a PHP expert, I'm a Java expert, and the assignment is not for me, its for a friend. They gave this test to him as part of a job interview. So the moral preaching is not necessary. I wouldn't get someone to do it for me, specially not for a job interview.

If its for a job interview he should be able to do it him self. and you being his friend should explain to him that this is wrong. i mean wtf is he going to be one of those developers that just steels other peoples code and calls it his own and cash's the check? coughSONY DEVELOPERScough