How do you make a check box?

jcvertin

How do you display a check box in PHP and how do you find out if it is checked or not? Thanks.

skirby

check boxes are made in html forms, ie:
<input type=checkbox name=test value=1>Test 1</input>
<input type=checkbox name=test value=2>Test 2</input>
<input type=checkbox name=test value=3>Test 3</input>

if included in a form, the action page will have the variable $test set to the checked value.

coditoergosum

Skirby almost got it. Not quite though. Input tags don't have an ending tag. They are standalone. Also, you're going to want to give each one a unique name. In the code below you'll send three values for $test, but it's going to use the last one, since it was set last. So, if you check "test 1" and "test 3", $test == 3. Use it like this:


<form action="somepage.php" method="post">
Test 1: <input type="checkbox" name="test1" value="checked">
Test 2: <input type="checkbox" name="test2" value="checked">
Test 3: <input type="checkbox" name="test3" value="checked">
<input type="submit">

Now, you'll have vars called $test1, $test2, and $test3, and if they are checked they will be equal to "checked". You could have it equal anything you want, by the way, i.e. "1", "true", "on"... whatever.

coditoergosum

Looking at Skirby's code again, it looks like he has checkboxes and radio buttons confused. The code he has would be closer to a radio button. Here is the code you'd use for a radio button:


<form action="somepage.php" method="post">
Test 1: <input type="radio" name="test" value="1">
Test 2: <input type="radio" name="test" value="2">
Test 3: <input type="radio" name="test" value="3">
<input type="submit">

Since you can only select 1 radio button from a group, the value of $test will be whichever radio button was selected. Again, you can use any value you'd like.

sfullman

OK, this is the proper html notation for a check box

It's important to understand that if a user DOESN'T check a checkbox, and the checkboxes value is "ilikethis", there won't be a BLANK variable called $ilikethis on the action page, there will be NO VARIABLE.

In otherwords, if you have an input field, and the user doesn't entry anything you have the field, it's just empty value. But for a checkbox or radio button, the variable is not even set.

This may be picky but a lot of people don't understand this.

Sam Fullman

sfullman

Also,

let's suppose you want to check the checkbox, so to speak, based on the presence of a variable, here's how:

This same concept applies for radio buttons.

Also for radio buttons, if you don't have a default checked value, you're defeating the whole purpose of radio buttons which is to ensure that SOMETHING but only ONE THING gets sent among a group of options.

Sam Fullman

coditoergosum

Pretty much exactly what I said... good point about the non-presence of the variable when nothing is checked though.

If we're going to be picky, your syntax is slightly wrong though. HTML 3.2+ standards say to use double quotes around the attribute values.


Works, but is incorrect: <input type=checkbox name=test value=1> 
Broken/incorrect: <input type=checkbox name=test value=this checkbox>
correct: <input type="checkbox" name="test" value="this checkbox">

The value="checked" I put in my first post wasn't meant to mean the checkbox's initial state is checked, it means the value of the var will be "checked" when passed to the script. Big difference... not sure if you realized that, just thought I would clarify.

As far as always setting a default for a group of radio buttons, I don't think it's absolutely necessary. There will be times where you want either nothing, or just one option.

skirby

wow, you guys are tough. I appreciate, and I'm sure the original poster did too, the corrections to my free-wheeling mixup of radio buttons (same name) and checkboxes. The lesson on current standards was good too...