Hi, what makes you think that you can pass a list of substrings to rindex?

If the substring is not found, index returns -1.

Your code is trying to match the entire substring. You should check each character individually. 

perl -Mstrict -wE '
my $str = "GAGAACATTAGTGGGTGCAGCGCACAAGCATGGCACATGTATACGTATGTAA";
say sprintf q{%s is last found at pos %s}, $_, rindex( $str, $_ ) for 
+qw/A C G T/;
'

[download]
Output: 
A is last found at pos 51
C is last found at pos 43
G is last found at pos 48
T is last found at pos 49

[download]

Also, always use strict; in your code: it will make Perl tell you about mistakes you've made: 

perl -Mstrict -wE '
my $str = "GAGAACATTAGTGGGTGCAGCGCACAAGCATGGCACATGTATACGTATGTAA";
say  rindex( $str, [ATCG] )
'

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Output: 
Bareword "ATCG" not allowed while "strict subs" in use at -e line 3.
Execution of -e aborted due to compilation errors.

[download]

Hope this helps!


The way forward always starts with a minimal test.

In reply to Re: Proper usage of rindex function? by 1nickt
in thread Proper usage of rindex function? by Anonymous Monk

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