@array = qw(one two three);
$p_str=join ",",@array;

##</code><code>##

@array = qw(one two three);
$p_str = '?'x@array;

##</code><code>##

@array = qw(one two three);
$p_str = join ",",'?'x@array;

##</code><code>##

@array = qw(one two three);
$p_str = join ",","???";

##</code><code>##

???