How could I check if substring is not included in string ?

lufthansa has asked for the wisdom of the Perl Monks concerning the following question:

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Re: How could I check if substring is not included in string ? by Corion (Patriarch) on Jan 26, 2009 at 10:39 UTC
The documentation says: If the substring is not found, index returns one less than the base, ordinarily -1 . So you will need to modify your test accordingly.	[reply]
Re: How could I check if substring is not included in string ? by moritz (Cardinal) on Jan 26, 2009 at 10:39 UTC
Read the documentation for index, it returns -1 on failure to find the substring. So the comparison should be `index(...) == -1` Btw Perl 6 makes this more intuitive by introducing a different boolean context, so that index can return a StrPos object that's true even if the substring was found at position 0. (Yes, Perl 5 could also make it return `"0 but True"`, but `"-1 but False"` doesn't work).	[reply] [d/l] [select]