You should always post the code your are using. Since your code does not even compile, we can not reproduce your error.

Post your actual code in code tags: see Writeup Formatting Tips.

use strict and warnings

From the code you have shown, there seems to be no need to read your whole file into an array; you could read it in line-by-line and process it as you go. That would save memory if your input file is large. UNTESTED:

use strict;
use warnings;

my $file = 'text.txt';
open my $fh, '<', $file or die "can not open $file: $!";
while (<$fh>) {
    chomp;
    my ($name, $roll_no, $class) = split /\|/;
    print "The student $name bearing roll number $roll_no is in class 
+$class\n";
}
close $fh;
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If you really do need to read the file into an array, you could slurp that file (and slurp it good!): File::Slurp.

Updated with code example.