use warnings;

my $string = "4 2 6 7";
my $i = 6; #use any value of $i

my @x = split / /, $string;
my $count = 0;

foreach (@x)
{
if($_ == $i) 
{ 
print "matched at position $count"; die $!;
}
$count++;
}
print "integer doesn't found in string";

Died at line 13.
matched at position 2