Help with file appending 1

[martinjburgess]

Hi I have a little routine that I am struggling with.

Bacically, I need to open a file and read the contents.
The contents are one entry per line in this form: 1339142221
The file name is $username.term
The other variable I have is $messid

What I need to do is read the file and compare the entries against $messid.
If $messid is not matched in the file then append the file with the new $messid.

Here is one of my attempts:

	fopen(FILE,"+>$members/$username.term");
	foreach(@list) {
			($msgid) = split(/\|/,$_);

	if($_ eq $msgid) { next; }

	else {

	print "$messid\n"; }
	}

Any help appreciated.

 

[feherke]

Hi

Please pick an Indent style and use it consistently. Makes your code easier to read and debug.

Your code needs some explanations :
[ul]
[li]Where are you reading from the file ? Into which variable ?[/li]
[li]What is the content of the @list variable ? Why are you [tt]split()[/tt]ing its values ?[/li]
[li]What are you trying to accomplish with that [tt]next[/tt] call ?[/li]
[li]Where should the writing to the file happen ?[/li]
[/ul]

Feherke.
[link feherke.github.com/]

http://feherke.github.com/

[/url]

 

[martinjburgess]

Thanks for the reply I am a novice at perl programming that is why I am here seeking help, my attempt is more than likely useless.

The file I am reading is called $username.term and has this layout:

1339142221
1339142970
1339143224
etc

I wish to read from the top of the file and see if any of the entries match an existing variable called $messid. If there is no match then append the file at the bottom of the list with $messid.

Example 1.
Lets say the $messid = 1339142970
The file is read and it matches the contents of one of the lines so does nothing.

Example 2.
Lets say that $messid = 1339144266
The file is read and no match is found so the 1339144266 ($messid) is appended to the bottom of the list.

I apologise for my lack of perl knowledge.

Many Thanks





I

 

[feherke]

Hi

Some things to note :
[ul]
[li]There is no fopen in Perl. Just [tt]open[/tt].[/li]
[li]The [tt]+>[/tt] access mode clobbers the file on read.[/li]
[/ul]

[navy]$messid[/navy][teal]=[/teal][green][i]'1339144266'[/i][/green][teal];[/teal]

[b]open[/b] FILE[teal],[/teal][green][i]"+<$members/$username.term"[/i][/green][teal];[/teal]

[navy]$found[/navy][teal]=[/teal][purple]0[/purple][teal];[/teal]
[b]while[/b] [teal]([/teal][b]chomp[/b][teal]([/teal][navy]$line[/navy][teal]=[/teal][green][i]<FILE>[/i][/green][teal]))[/teal] [teal]{[/teal]
  [navy]$found[/navy][teal]=[/teal][purple]1[/purple] [b]if[/b] [navy]$line[/navy] [b]eq[/b] [navy]$messid[/navy][teal];[/teal]
[teal]}[/teal]

[b]print[/b] FILE [green][i]"$messid\n"[/i][/green] [b]unless[/b] [navy]$found[/navy][teal];[/teal]

[b]close[/b] FILE[teal];[/teal]

Feherke.
[link feherke.github.com/]

http://feherke.github.com/

[/url]

 

[martinjburgess]

Thank you for being so prompt.

Can I explain that $messid is a message id and changes with each message. The variable must be similar on this forum it is probably $qid, in the address bar it says qid=1685298 for this post.

The file $username.temp is not being created when a member accesses the post for the first time so there is nothing to read.

Is there a routine that will create the empty file first if it doesn't exist?

Cheers

 

[feherke]

Hi

Note that the above code supposes that you may want to do other operations too.

If the only reason of the file reading & writing is the search and appending of $messid, you can optimize it : as soon as you find the matching code, jump directly to the end of file.

[navy]$messid[/navy][teal]=[/teal][green][i]'1339144266'[/i][/green][teal];[/teal]

[b]open[/b] FILE[teal],[/teal][green][i]"+<$members/$username.term"[/i][/green][teal];[/teal]

[navy]$found[/navy][teal]=[/teal][purple]0[/purple][teal];[/teal]
[b]while[/b] [teal]([/teal][b]chomp[/b][teal]([/teal][navy]$line[/navy][teal]=[/teal][green][i]<FILE>[/i][/green][teal]))[/teal] [teal]{[/teal]
  [b]if[/b] [teal]([/teal][navy]$line[/navy] [b]eq[/b] [navy]$messid[/navy][teal])[/teal] [teal]{[/teal]
    [navy]$found[/navy][teal]=[/teal][purple]1[/purple][teal];[/teal]
    [b]seek[/b] FILE[teal],[/teal][purple]0[/purple][teal],[/teal][purple]2[/purple][teal];[/teal]
  [teal]}[/teal]
[teal]}[/teal]

[b]print[/b] FILE [green][i]"$messid\n"[/i][/green] [b]unless[/b] [navy]$found[/navy][teal];[/teal]

[b]close[/b] FILE[teal];[/teal]

This can be simplified even more by not using a separate variable to store the found status, but simply closing the file, then checking its status :

[navy]$messid[/navy][teal]=[/teal][green][i]'1339144266'[/i][/green][teal];[/teal]

[b]open[/b] FILE[teal],[/teal][green][i]"+<$members/$username.term"[/i][/green][teal];[/teal]

[b]while[/b] [teal]([/teal][b]chomp[/b][teal]([/teal][navy]$line[/navy][teal]=[/teal][green][i]<FILE>[/i][/green][teal]))[/teal] [teal]{[/teal]
  [b]close[/b] FILE [b]if[/b] [navy]$line[/navy] [b]eq[/b] [navy]$messid[/navy][teal];[/teal]
[teal]}[/teal]

[b]if[/b] [teal]([/teal][b]tell[/b][teal]([/teal]FILE[teal])!=-[/teal][purple]1[/purple][teal])[/teal] [teal]{[/teal]
  [b]print[/b] FILE [green][i]"$messid\n"[/i][/green][teal];[/teal]

  [b]close[/b] FILE[teal];[/teal]
[teal]}[/teal]

Feherke.
[link feherke.github.com/]

http://feherke.github.com/

[/url]

 

[feherke]

Hi

Is there a routine that will create the empty file first if it doesn't exist?

Well, [tt]open[/tt] will create it when used with mode [tt]>[/tt], [tt]>>[/tt] or [tt]+>[/tt].

So you will have to check the existence of the file and use either [tt]+<[/tt] or [tt]+>[/tt] mode accordingly :

[b]open[/b] FILE[teal],-[/teal]f [green][i]"$members/$username.term"[/i][/green][teal]?[/teal][green][i]'+<'[/i][/green][teal]:[/teal][green][i]'+>'[/i][/green][teal],[/teal][green][i]"$members/$username.term"[/i][/green][teal];[/teal]

Feherke.
[link feherke.github.com/]

http://feherke.github.com/

[/url]

 

[martinjburgess]

Thank you so much, all working now.