if ( $name1 = "") {
    $age1 = "";
}

##</code><code>##

@student = (\$name1, \$name3, \$name5, \$name7, \$name9, \$name11);

@all = (\$age1, \$age2, \$age3, \$age4, \$age5, \$age6);

for ($i = 0; $i = 5; $i++){

if ( $student[$i] ... ) {
    $all[$i] = "";
}elsif ($student[$i] ... ) {
    $all[$i] = "";
}elsif ($student[$i] ... ) {
    $all[$i] = "";
}
}