php : How to check a field have blank/empty/NULL value?

Question

I want to display an error when a variable have a BLANK value or EMPTY or NULL value. for example variable is shown below:

 $mo = strtotime($_POST['MondayOpen']);

and
var_dump($_POST['MondayOpen']) returns string(0) "".

Now I go with below approach

First want to find which type of variable $mo is ?(string or integer or other)
Which function is better to find that $mo having no value.

I conduct a test with $mo and got these results

is_int($mo);//--Return nothing
is_string($mo); //--Return bool(false) 
var_dump($mo);  //--Return bool(true)                   
var_dump(empty($mo));//--Return bool(true) 
var_dump($mo==NULL);//--Return bool(true) 
var_dump($mo=='');//--Return nothing

Please suggest an optimum and right approach to check the variable integrity

As a side note, you are using == which tests for equality, such as 1 == '1' which would evaluate to true. But when you use === it tests if the types are equal. In my example 1 === '1' will return false, since int is not a String. — Anthony Forloney
– Anthony Forloney, Commented Feb 4, 2010 at 16:59

Chad · Accepted Answer · 2010-02-04 16:50:53Z

4

var_dump outputs variables for debugging purposes, it is not used to check the value in a normal code. PHP is loosely typed, most of the time it does not matter if your variable is a string or an int although you can cast it if you need to make sure it is one, or use the is_ functions to check.

To test if something is empty:

if ( empty( $mo ) ) {
  // error
}

empty() returns true if a variable is 0, null, false or an empty string.

answered Feb 4, 2010 at 16:50

Chad

411 bronze badge

Sign up to request clarification or add additional context in comments.

Comments

MANCHUCK · Accepted Answer · 2010-02-04 17:18:49Z

3

doing strtotime will return false if it cannot convert to a time stamp.

$mo = strtotime($_POST['MondayOpen']);
if ($mo !== false)
{
//valid date was passed in  and $mo is type int
}
else
{
//invalid date let the user know
}

answered Feb 4, 2010 at 17:18

MANCHUCK

2,4721 gold badge16 silver badges23 bronze badges

Comments

Anthony Forloney · Accepted Answer · 2010-02-04 16:56:43Z

3

PHP offers a function isset to check if a variable is not NULL and empty to check if a variable is empty.

To return the type, you can use the PHP function gettype

if (!isset($mo) || is_empty($mo)) {
 // $mo is either NULL or empty.
 // display error message
 }

edited Feb 4, 2010 at 16:56

answered Feb 4, 2010 at 16:50

Anthony Forloney

92.1k14 gold badges119 silver badges116 bronze badges

2 Comments

goat Over a year ago

if (!isset($mo) || empty($mo)) is redundant. if (empty($mo)) has the same behavior.

Olivier Over a year ago

Problem with "empty($var)" function is that consider $var="0" as ... empty. Which is obviously not ...

Sarfraz · Accepted Answer · 2010-02-04 16:50:40Z

0

You can check its type using:

gettype($mo);

but null and empty are different things, you can check with these functions:

if (empty($mo))
{
  // it is empty
}

if (is_null($mo))
{
  // it is null
}

Another way to check if variable has been set is to use the isset construct.

if (isset($mo))
{
  // variable has been set
}

answered Feb 4, 2010 at 16:50

Sarfraz

384k81 gold badges561 silver badges613 bronze badges

Collectives™ on Stack Overflow

php : How to check a field have blank/empty/NULL value?

4 Answers 4

Comments

Comments

2 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Comments

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related