Printing the comment

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Here is what I am trying to do. When the page loads, in an "if" loop, it checks the information of the $value variable against what is in the @Comm array. It goes through a "for" loop for each of the slices in the @Comment array. Every time when I check for bugs, it always find a problem with the "if" loop. Look over this and see if you can fix it.

#!/usr/bin/perl 

# Loads the CGI Module
use CGI;

# creates a new CGI object
my $page = new CGI;

# This will print a standard HTML header
print $page->header;

# Grab a named CGI parameter

my $value = $page->param(Comic);

##########declare the names of the files for the loop
@Comm = ('Images/Le_Comic.jpg', 'Images/Le_Comic2.jpg', 'Images/Le_Com
+ic3.jpg',
'Images/Le_Comic4.jpg', 'Images/Le_Comic5.jpg', 'Images/Le_Comic6.jpg'
+, 
'Images/Le_Comic7.jpg', 'Images/Le_Comic8.jpg', 'Images/Le_Comic9.jpg'
+);
##########
#Open up the comments file
open (FILE, '../Comment.txt') or die "It could not be found.";

#Save the contents of the FILE handle to an array
@Comment = <FILE>;

#do a for loop to make it go through the test
for ($i=0; $i<=#@Comment; $i++) {

#Do an if loop to go through and save the right thing
if ($value == $Comm[$i]) {
$Como = $Comment[$i];
          }
}
# Then:

print "<HTML><HEAD>\n";
print <<ENDMETA;
  <META NAME="GENERATOR" CONTENT="Adobe PageMill 3.0 Win">
  <TITLE>Animetion Station &gt; Webcomic</title>
  <LINK REL="stylesheet" HREF="../Style.css" TYPE="text/css">
ENDMETA
print "</head><BODY>\n";

print <<ENDHTML;
<P><CENTER><DIV STYLE="background-color: #0099FF; font-family: Comic S
+ans MS; font-size: 20px; width: 200px; color: white;">Web
Comics</div></center></p>

<P><TABLE WIDTH="757" BORDER="0" CELLSPACING="1" CELLPADDING="0" HEIGH
+T="294">
  <TR>
    <TD WIDTH="14%" VALIGN="TOP" ALIGN="CENTER" HEIGHT="293">


 <div class="Standard">

    <P><CENTER><A HREF="../index.htm">[Home]</a> <HR>
    <A HREF="../Gallery.shtml">[Gallery]</a> <HR>
    <A HREF="../Manga.shtml">[Manga]</a> <HR>
    <A HREF="../Video_Review.shtml">[Video Reviews]</a> <HR>
    <A HREF="../Links.shtml">[Links]</a> <HR>
    <A HREF="../Web_Comic.shtml">[Web Comic]</a></center></td>
    <TD VALIGN="TOP" WIDTH="270" HEIGHT="131">
    
    </div>

    </td> 

    <TD WIDTH="86%" VALIGN="TOP" BGCOLOR="#3366ff">
    <P><IMG SRC="../$value"></p><br>
    <p>$Como</p>

    <P><IMG SRC="../Images/Comic_Face.jpg" WIDTH="57" HEIGHT="54" ALIG
+N="BOTTOM" BORDER="0" NATURALSIZEFLAG="3">
    <IMG SRC="../Images/Comic_Face2.jpg" WIDTH="60" HEIGHT="55" ALIGN=
+"BOTTOM" BORDER="0" NATURALSIZEFLAG="3">
    <IMG SRC="../Images/Comic_Face3.jpg" WIDTH="60" HEIGHT="62" ALIGN=
+"BOTTOM" BORDER="0" NATURALSIZEFLAG="3">
    <IMG SRC="../Images/Comic_Face4.jpg" WIDTH="60" HEIGHT="60" ALIGN=
+"BOTTOM" BORDER="0" NATURALSIZEFLAG="3"></td>
  </tr>
</table>
ENDHTML

print "</body></html>\n";
[download]

Comment on Printing the comment Download Code

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Re: Printing the comment by wog (Curate) on Oct 06, 2001 at 03:58 UTC
Your problem is that you are commenting out the latter part of your for loop and thus the `if` statement is interpreted as in the second part of the for loop, and a syntax error. The offending code segment is: `#do a for loop to make it go through the test for ($i=0; $i<=#@Comment; $i++) { #Do an if loop to go through and save the right thing if ($value == $Comm[$i]) { $Como = $Comment[$i]; } }` [download] When perl parses this, it interpretes it as: `for($i=0; $i <= if ($value==$Comm[$i]) { ....` [download] Because the `#@Comment ...` starts a comment. You probably meant to use `$#Comment` instead. Alternately, it might be better to re-write that for loop to use the foreach-style: `my $Como; foreach my $i (0..$#Comment) { $Como = $Comment[$i], last if $Comm[$i] == $value; } # ... and you should add error-checking: unless (defined $Como) { # do something here if we didn't find anything }` [download] update: but, you are trying to compare `$value` to string, so you should replace that `==` (which compares things as numbers) with an `eq` (which compares them as strings): `# ... $Como = $Comment[$i], last if $Comm[$i] eq $value;` [download] (Note that you could write that statement using the `if (...) { ... }` form, too, of course. You may find that clearer.) In the future it would be a good idea to use strict and warnings. And taint checks.	[reply] [d/l] [select]

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Re: Printing the comment
by wog (Curate) on Oct 06, 2001 at 03:58 UTC

if

#do a for loop to make it go through the test
for ($i=0; $i<=#@Comment; $i++) {

#Do an if loop to go through and save the right thing
if ($value == $Comm[$i]) {
$Como = $Comment[$i];
          }
}
[download]

When perl parses this, it interpretes it as:

for($i=0; $i <= if ($value==$Comm[$i]) { ....
[download]

Because the #@Comment ... starts a comment. You probably meant to use $#Comment instead. Alternately, it might be better to re-write that for loop to use the foreach-style:

my $Como;
foreach my $i (0..$#Comment)
{
  $Como = $Comment[$i], last if $Comm[$i] == $value;
}

# ... and you should add error-checking:
unless (defined $Como) { 
  # do something here if we didn't find anything
}
[download]

update: but, you are trying to compare $value to string, so you should replace that == (which compares things as numbers) with an eq (which compares them as strings):

# ...
  $Como = $Comment[$i], last if $Comm[$i] eq $value;
[download]

(Note that you could write that statement using the if (...) { ... } form, too, of course. You may find that clearer.)

In the future it would be a good idea to use strict and warnings. And taint checks.

[reply]
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[select]