PHP查询选项定义中的PHP下拉框

Question

I have been trying to decipher the option part of this: echo "<option value='" . $row['PcID'] . "'>" . $row['PcID'] . "</option>"; taken from Populate a Drop down box.....

can someone kindly explain what the periods do? and why when i do this: print "<option value='".$wrow['week_num']."'>".$wrow['week_name']."</option><br> "; I only get only the week name in the list.

$wquery="select week_num,week_name from stats_week";
$wresult=mysql_query($wquery);
print "Select Week:<select name=Week_select><br>
";
while ($wrow=mysql_fetch_assoc($wresult)){
    print "<option value='".$wrow['week_num']."'>".$wrow['week_name']."</option><br>
";    
}
print "</select>";

Answer 1

In PHP, the period is the concatentation operator. Putting the periods in tells PHP to concatenate strings, See this page:

http://www.php.net/manual/en/language.operators.string.php