documentation provided for the functions:

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chomp
This is an alternative to the chop() function. It removes characters at the end of strings corresponding to the $INPUT_LINE_SEPARATOR ($/). It returns the number of characters removed. It can be given a list of strings upon which to perform this operation. When given no arguments, the operation is performed on $_.

chop
This function removes the last character of a string and returns that character. If given a list of arguments, the operation is performed on each one and the last character chopped is returned.
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these two functions are very much alike... they both remove one (or more) characters from the end of a string... So how are they different you ask? Chomp() ONLY removes new line characters (these are specified in $/), whereas Chop() removes anything that is at the end of the string (it really doesn't care what it is)...

let's demonstrate these two functions:

#chomp() EXAMPLES
$a = "abcdefghij";
chomp($a);
print $a;  #would return exact string... nothing to remove

$a = "abcdefghij\n";
chomp($a);
print $a;  #would return 'abcdefghij', removed newline

$a = "abcdefghij\n";
$b = chomp($a);
print $b;  #would return 1, it did remove something for sure

#chop() EXAMPLES
$a = "abcdefghij";
chop($a);
print $a;  #this would return 'abcdefghi'

$a = "abcdefghij";
$b = chop($a);
print $b;  #this would return 'j'
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remember.. this with a little bit of usefulness chop() can be the same as chomp()

$a = "abcdefghij\n";
if ($a =~ /\n$/) { chop $a; } #this could also be \r\n if on windows p
+latform
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most of the time, you'll want to chomp(), but you might want to use chop() with regexes for the same output