Php if($_POST) vs if(isset($_POST))

php post isset
Aycan Yaşıt picture Aycan Yaşıt · Jan 5, 2016 · Viewed 24.2k times · Source

I have a simple form as demonstrated below:

<form action="" method="post">
  <input type="text" />
  <input type="submit" value="SEND" />
</form>

When I try to receive data sent from this form via if($_POST), I fail, but when try with isset, I success.

if($_POST){
  echo 'a'; //Doesn't print anything.
}
if(isset($_POST)){
  echo 'b'; //Prints 'b'
}

I guess the reason behind it is missing name attribute in my form input, but I can't understand why if($_POST) and isset($_POST) react different ways in this case.

Answer

Quentin picture Quentin · Jan 5, 2016

isset determine if a variable is set and is not NULL. $_POST will always be set and will always be an array.

Without isset you are just testing if the value is truthy. An empty array (which $_POST will be if you aren't posting any data) will not be truthy.

Related questions

Using if(isset($_POST['submit'])) to not display echo when script is open is not working

I have a little problem with my if(isset($_POST['submit'])) code. What I want is some echos and a table to not appear when the script is open but I do want it to show when the submit button …

Read More
Why do I need the isset() function in php?

I am trying to understand the difference between this: if (isset($_POST['Submit'])) { //do something } and if ($_POST['Submit']) { //do something } It seems to me that if the $_POST['Submit'] variable is true, then it is set. Why would I …

Read More
PHP Make a simple if-isset-empty function

I'm coding a worksheet app for a printer company. I'm getting flood of forms. For every single input field I have to check if the $_POST variables are set, and if, so echo back the value. (In case of some …

Read More