How to Check if $_POST Exists in PHP?

How to Determine the Existence of $_POST

In PHP programming, $_POST is a superglobal variable that holds data submitted by an HTML form. To access this data, it's essential to check whether $_POST exists before attempting to retrieve specific values.

Using isset() to Check Existence

One way to determine the existence of $_POST is through the isset() function. This function returns true if the specified variable is set and has a non-null value, or false otherwise.

For instance, the following code checks if $_POST['fromPerson'] exists before using it to construct a string:

<code class="php">if( isset($_POST['fromPerson']) )
{
    $fromPerson = '+from%3A'.$_POST['fromPerson'];
    echo $fromPerson;
}</code>

In this example, if $_POST['fromPerson'] exists, it generates and echoes the $fromPerson string. Otherwise, nothing is printed.

Avoiding Empty Value with isset()

The code you provided attempts to use the bang operator (!) to check if $_POST['fromPerson'] is empty. However, this approach is not recommended. Instead, you can use isset() to avoid printing empty values, as demonstrated in the code above.

By leveraging the power of isset(), you can handle the existence of $_POST and retrieve data from its keys effectively in your PHP scripts.

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