use warnings;                                                                    
                                                                                 
while (defined(my $line = <DATA>)) {                                             
    print "\n";                                                                  
    chomp($line);                                                                
    my ($k, $v) = split /\s*=\s*/, $line;                                        
    print "The $k key has $v value\n";                                           
    output_flush();                                                              
}                                                                                
                                                                                 
sub output_flush {                                                               
    # Keep our STDOUT and STDERR in sync with each other, and in iteration order:
    $_->flush for *STDERR, *STDOUT;                                              
}                                                                                
                                                                                 
__DATA__                                                                         
[main]                                                                           
foo=bar                                                                          
baz=buzz                                                                         
                                                                                 
[config]                                                                         
bingo=42                                                                         

##</code><code>##

Use of uninitialized value $v in concatenation (.) or string at mytest.pl line 12, <DATA> line 1.
The [main] key has  value

The foo key has bar value

The baz key has buzz value

Use of uninitialized value $k in concatenation (.) or string at mytest.pl line 12, <DATA> line 4.
Use of uninitialized value $v in concatenation (.) or string at mytest.pl line 12, <DATA> line 4.
The  key has  value

Use of uninitialized value $v in concatenation (.) or string at mytest.pl line 12, <DATA> line 5.
The [config] key has  value

The bingo key has 42 value

##</code><code>##

my $c;
while ($c++ < 10) {
    print "$c\n";
}