18.104.22.168 Examples of Invalid Single-quoted Strings
In finishing our discussion of singled-quoted strings, consider these
examples of strings that are not legal because they violate the
exceptions we talked about above:
'You cannot do this: \'; # INVALID: the ending \ cannot be alone
'It is 5 o'clock!' # INVALID: the ' in o'clock should be escaped
'Three \'s: \\\\\'; # INVALID: the final \ escapes the ', thus
# the literal is not terminated
'This is my string; # INVALID: missing close quote
Sometimes, when you have invalid string literals such as in the example
above, the error message that Perl gives is not particularly intuitive.
However, when you see error messages such as:
(Might be a runaway multi-line '' string starting on line X)
Bareword found where operator expected
Bareword "foo" not allowed while "strict subs" in use
It is often an indication that you have runaway or invalid strings.
Keep an eye out for these problems. Chances are, you will forget and
violate one of the rules for single-quoted strings eventually, and then
need to determine why you are unable to run your Perl program.