Chapter 14. Strings and Sorting
As we mentioned near the beginning of this book, Perl is designed to be good at solving programming problems that are about 90% working with text and 10% everything else. So it’s no surprise that Perl has strong text-processing abilities, including all that we’ve done with regular expressions. But sometimes the regular expression engine is too fancy, and you’ll need a simpler way of working with a string, as you’ll see in this chapter.
Finding a Substring with index
Finding a substring depends on where you have lost it. If you happen
to have lost it within a bigger string, you’re in luck because
the index
function can
help you out. Here’s how it looks:
$where = index($big, $small);
Perl locates the first occurrence of the small string within the
big string, returning an integer location of the first character. The
character position returned is a zero-based value—if the substring is
found at the very beginning of the string, index
returns 0
. If it’s one character later, the return
value is 1
, and so on. If the
substring can’t be found at all, the return value is −1
to indicate that.[26] In this example, $where
gets 6
:
my $stuff = "Howdy world!"; my $where = index($stuff, "wor");
Another way you could think of the position number is the number
of characters to skip over before getting to the substring. Since
$where
is 6
, we know that we have to skip over the first
six characters of $stuff
before we
find wor
.
The index
function will always report the location ...
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