my @wanted = ( 'C', 'C++','.NET', );
my $str = '.net, .net; C# .NET Cobol .NET C++ .NET .NETER c# IT x.NET';

my %split_str;
$split_str{ +uc }++ for split /[ ;,]+/, $str;

say "$_: " . ( $split_str{$_} || 0 ) for @wanted;