Dear Monks--
Sorry if I haven't provided enough information

O.K. Here is all the code I can think is relevant. You wanted to know what line was generating the error ("Modification of a read-only value attempted"). It was the last line I'm giving here; i.e. the sort line. Is it worth noting that elsewhere in the program I am able to access any element of the @courselist array without problem? 
foreach $try (@text){ 
$try =~/^(.*?)\|(.*?)\|(.*?)\|(.*?)\|(.*?)\|(.*?)\|(.*?)\|(.*?)\|(.*?)
+\|(.*?)\|(.*?)$/gs or die "<br />problem with $try<br />"; 
my $Institution = $1; 
my $CourseNumber = $2;
my $Professor = $3;
my $Enrollment = $4; 
........  
if (!$CourseNumber && !$Institution){last;};
if ($CourseNumber ne $LastCourseNumber){    
$courseindex = $courseindex + 1;
$courselist[$courseindex] = [$Institution, $CourseNumber, $Professor, 
+$CourseTitle, $Enrollment];
};
$LastCourseNumber = $CourseNumber; 
}; 

@courselist =  sort { $a->[0] cmp $b->[0] || $a->[1] cmp $b->[1] } @co
+urselist;

[download]
To reiterate, what I'd like to do is to sort @courselist by $courselist[n][0] (i.e. $Institution, and within that sort, by $courselist[n][1], i.e. $CourseNumber.

This is an example of what I have in @courselist:
$courselist[0] = ["UM", "CS 34", "Smith", "34"]
$courselist[1] = ["AC", "PHIL 13", "Barry", "45"]
$courselist[2] = ["UM", "BIO 567", "Houlihan", "12"]

[download]
and I want it to end looking like this: 
$courselist[0] = ["AC", "PHIL 13", "Barry", "45"]
$courselist[1] = ["UM", "BIO 567", "Houlihan", "12"]
$courselist[2] = ["UM", "CS 34", "Smith", "34"]

[download]

I don't understand why I'm getting the error message, and I'm still not sure about the sort...

Thanks for your continuing efforts!

In reply to Re: How to fix error: Modification of a read-only value by Gnat53
in thread How to fix error: Modification of a read-only value by Gnat53

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