指數RINDEX在Perl

Question

我混淆指數和RINDEX而寫的perl script.What是Perl指數和RINDEX之間的區別（用簡單的例子說明）

Answer 1

perl -E 'say rindex("bar foo bar foo", "foo")' 
           ^__ found first substring from right side 
12 

perl -E 'say index("bar foo bar foo", "foo")' 
         ^__ found first substring from left side 
4