CODEWITHSUNDEEP
perl
Jared Harmon
Jared Harmon

Reputation: 58

Perl - How to fix error "Use of uninitialized value in numeric lt (<)" in if statement

I am creating a basic bubble sort and I don't understand why i am getting this error Use of uninitialized value in numeric lt (<) at line 10.

#!/usr/bin/perl -w
use strict;
use warnings;

my @nums = (7,3,5,8,5,2,3,5,7,3,5);
my $length = @nums;

for(my $i = 0; $i < $length; $i++){
        for(my $j = 0; $j < $length; $j++){
                if($nums[$j] lt $nums[$j+1]){
                        my $temp = $nums[$j];
                        $nums[$j] = $nums[$j+1];
                        $nums[$j+1] = $temp;
                }
        }
}

It seems to be having issues in the if comparison. I made sure that my array was properly initialized with these values and they are. If i print the values before the for loops they print fine and are initialized.

I assume I am just missing something very simple but I'm honestly lost.

Upvotes: 1

Views: 1444

Answers (1)

Graeme Perrow
Graeme Perrow

Reputation: 57248

In your inner loop, $j loops up to $length-1. At that point, $nums[$j] is the last element of the array. Then you compare it with $nums[$j+1] which doesn't exist.

Upvotes: 1

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