The print statement
    print"$config[$t][0]\n";
in the print loop of example (1) of the OP suggests the possibility* you are dealing not with an array of strings, but with an array of array references each of which has at least one element, the first, that is a string.

If this is so, the following code addresses this case, both with more and less redundant, as NetWallah has pointed out, map approaches, and with a more 'standard' for-loop. 

>perl -wMstrict -le
"my @config = ([ 'fee fie' ], [ 'foe'], [ 'fum' ],);
 printf qq{'$_->[0]' } for @config;  print '';
 ;;
 @config = map { $_->[0] =~ s{(f[eio]e)}{\u$1}xmsg;  $_; } @config;
 printf qq{'$_->[0]' } for @config;  print '';
 ;;
 map { $_->[0] =~ s{ (F [eio] e) }{\U$1}xmsg } @config;
 printf qq{'$_->[0]' } for @config;  print '';
 ;;
 for my $ar (@config) {
   $ar->[0] =~ s{ (F [EIO] E) }{\L$1}xmsg;;
   }
 printf qq{'$_->[0]' } for @config;  print '';
"
'fee fie' 'foe' 'fum'
'Fee Fie' 'Foe' 'fum'
'FEE FIE' 'FOE' 'fum'
'fee fie' 'foe' 'fum'

[download]

* I know this is a possibility because if you had been dealing with an array of simple strings, you would have seen an error or a bunch of warnings because, of course, you're running with strictures and warnings enabled.

In reply to Re: String substitution inside an array by AnomalousMonk
in thread String substitution inside an array by Monkomatic

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