how to collect checkbox values?

[mshen]

I try the small program.but I only collect one value when I select more select .I want to know how to collect more values when I select more .please show me how to do it.

<?php if($c1){echo $c1; }?>

<form name="form1" method="post" action="">
<p>
<input name="c1" type="checkbox" id="c1" value="11">
1</p>
<p>
<input name="c1" type="checkbox" id="c1" value="22">
2</p>
<p>
<input name="c1" type="checkbox" id="c1" value="33">
3</p>
<p>
<input type="submit" name="Submit" value="Submit">
</p>
</form>

for the small program.I think the output is "11,22,33" when I select all ,but the real output is "33".why?

Thanks a lot.

[eoghain]

The reason is that you have named all of your checkboxes the same. PHP just overwrites the values with the last one it receives. Change the names and you will be able to check all of them. But remember that if the user doesn't select a check box then that variable won't be created by PHP so you will need to check it with [man]isset/man;

[ahundiak]

Use name="c1[]" then you will get back an array of checked values.

[Cleric]

As ahundiak has stated, but should offer a little explanation as to understand what happens with PHP:

In case of check boxes, the only way to to get multiple values back is to add brackets, [], the end of the name property of the check box tag. When the form is submited to a PHP script, it will see the brackets and say "Oh, that is an array!" and will store all the values accordingly.

Now this does produce a small problem if you want to use Javascript to do something with said check boxes, but can be handled reasonably well.