Append adds to end of last line and not new line - perl

Question

So lets say I have text file that looks like this
new york
new jersey
florida
South Carolina
I'm going to append california to it, but when I do it ends up looking like this:
new york
new jersey
florida
South Carolinacalifornia
How can I make it so it appends to a new line? I thought about just making a new line before the appending of california but then every time I run the script it'll just have gaps between the lines because of the new line

Answer 1

Presumably your file is a list of states all on their own line. Your issue appears to be that the line: "South Carolina", is missing a newline character at the end, which is inconsistent with the rest of your data.
This is a data issue. With hidden characters shown your data looks like this:
new york\n
new jersey\n
florida\n
South Carolina
When it should look like this:
new york\n
new jersey\n
florida\n
South Carolina\n
In a scenario like this where your data is inconsistent the best way to programmatically fix it is to check if the file ends in a newline, and if not, append one.

Answer 2

The issue is that the final line of your original file isn't terminated with a newline. If its contents are within your control then the best solution is simply to ensure that every line printed to the file is properly terminated, but if you have to deal with malformed data then there are a few options
The first, as people have said, is to read the entire file into memory, remove any existing terminators with chomp, and print them back out to the file with the correct newline after all of them
If your file is of any significant size then this approach is wasteful. You may avoid the rewriting by reading the last character of the file and checking whether it is a newline as required. Then, when the file is opened for appending, you can first add a newline if it was originally missing, followed by the new data record. That would look like this
The seek call is used to move the read position to just before the last character, then <$fh> will read the final character which can be compared to "\n" to establish whether the file is properly terminated
Note that, if there is any chance that the file is completely empty or non-existent before your program runs, then you will have to code for the case where the open fails or the <$fh> returns undef
use strict;
use warnings 'all';
use autodie;
use Fcntl ':seek';
my ($file) = #ARGV;
my $terminated = do {
open my $fh, '<', $file;
seek $fh, -1, SEEK_END;
<$fh> eq "\n";
};
open my $fh, '>>', $file;
print $fh "\n" unless $terminated;
print $fh "california\n";
close $fh;

Answer 3

As mentioned by Dkwan33 this might be data issue. You can use "od" command to run and see if every line is ending with \n or not.
od -bc data.txt
0000000 156 145 167 040 171 157 162 153 012 156 145 167 040 152 145 162
n e w y o r k \n n e w j e r
0000020 163 145 171 012 146 154 157 162 151 144 141 012 123 157 165 164
s e y \n f l o r i d a \n S o u t
0000040 150 040 103 141 162 157 154 151 156 141 012
h C a r o l i n a \n
0000053
If you want to handle it via Perl then I would suggest you to first do the "chomp" on each line and then print that line with \n.