my $i;
for $i ( 0 .. 10 ) {
    last if <somecondition>;
    ...
}
my $x = substr $somestring, 0, $i;

##</code><code>##

my $i=0;
{
    ...
    last if <somecondition>;
    $i++;
    redo;
}
my $x = substr $somestring, 0, $i;

##</code><code>##

$i=0; 
do{ 
    ...
    $i++ 
} until <somecondition>;
my $x = substr $somestring, 0, $i;

##</code><code>##

my $i=42; 
for my $i (1..10){ 
    print $i; 
} 
print $i;
## gives
1 2 3 4 5 6 7 8 9 10 42