48

How do I check in PHP whether a checkbox is checked or not?

NullPoiиteя
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Karem
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  • [http://www.html-form-guide.com/php-form/php-form-checkbox.html](http://www.html-form-guide.com/php-form/php-form-checkbox.html) This covers checkboxes, and checkbox groups. – McAden Feb 15 '10 at 21:09

5 Answers5

73

If the checkbox is checked, then the checkbox's value will be passed. Otherwise, the field is not passed in the HTTP post.

if (isset($_POST['mycheckbox'])) {
    echo "checked!";
}
bryjohns
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Tomas Markauskas
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    Does this work if a `checkbox` was checked, then unchecked and then the form was submitted? – Jo Smo Aug 09 '15 at 12:53
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    Yes, the browser only sends the state that the checkbox was in, when the user clicked the submit button, how many times the checkbox was checked or unchecked doesn't matter. – Tomas Markauskas Aug 09 '15 at 19:40
  • Thank you. `ASP.NET MVC` handles it different, so i though that it would be similar in `PHP`, but looks like it's not. :) – Jo Smo Aug 10 '15 at 05:35
30

you can check that by either isset() or empty() (its check explicit isset) weather check box is checked or not

for example 

  <input type='checkbox' name='Mary' value='2' id='checkbox' />

here you can check by 

if (isset($_POST['Mary'])) {
    echo "checked!";
}

or

if (!empty($_POST['Mary'])) {
    echo "checked!";
}

the above will check only one if you want to do for many than you can make an array instead writing separate for all checkbox try like 

<input type="checkbox" name="formDoor[]" value="A" />Acorn Building<br />
<input type="checkbox" name="formDoor[]" value="B" />Brown Hall<br />
<input type="checkbox" name="formDoor[]" value="C" />Carnegie Complex<br />

php

  $aDoor = $_POST['formDoor'];
  if(empty($aDoor))
  {
    echo("You didn't select any buildings.");
  }
  else
  {
    $N = count($aDoor);
    echo("You selected $N door(s): ");
    for($i=0; $i < $N; $i++)
    {
      echo htmlspecialchars($aDoor[$i] ). " ";
    }
  }
NullPoiиteя
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  • How to make it only be able to check one checkbox from multiple checkbox and insert it into database? `insert into table_name (choice) VALUES ('$aDoor')` – Al Kush Nov 02 '14 at 10:28
  • @AlKush use radio box instead ;) – NullPoiиteя Nov 02 '14 at 11:19
  • Thanks. And yes I have decided to use radio buttons. But how to make it required. For instance. I have three radio buttons which has not been checked. But I want to remind the user that they have to choose one of them. – Al Kush Nov 02 '14 at 11:27
  • just check weather it is set or not with isset ex. if(isset($_POST['radio_buttonname'])) – NullPoiиteя Nov 02 '14 at 11:43
9

Try this

index.html

<form action="form.php" method="post">
    Do you like stackoverflow?
    <input type="checkbox" name="like" value="Yes" />  
    <input type="submit" name="formSubmit" value="Submit" /> 
</form>

form.php

<html>
<head>
</head>
<body>

<?php
    if(isset($_POST['like']))
    {
        echo "<h1>You like Stackoverflow.<h1>";
    }
    else
    {
        echo "<h1>You don't like Stackoverflow.</h1>";
    }   
?>

</body>
</html>

Or this 

<?php
    if(isset($_POST['like'])) && 
    $_POST['like'] == 'Yes') 
    {
        echo "You like Stackoverflow.";
    }
    else
    {
        echo "You don't like Stackoverflow.";
    }   
?>
Community
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Michael B.
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7

If you don't know which checkboxes your page has (ex: if you are creating them dynamically) you can simply put a hidden field with the same name and 0 value right above the checkbox. 

<input type="hidden" name="foo" value="0" />
<input type="checkbox" name="foo" value="1">

This way you will get 1 or 0 based on whether the checkbox is selected or not.

Can Celik
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1

I love short hands so:

$isChecked = isset($_POST['myCheckbox']) ? "yes" : "no";
Omidoo
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