哪个更正确，更快，更安全：if（isset（$ var））{do foo} OR if（$ var）{do foo}？

Question

I am in the process of creating an associative array called errMsgs[] that will hold error messages that correspond to a particular <input> field error. Which form of testing errMsgs[] is more correct, faster, and safer? Does either method have important advantages or disadvantages?

Contact Form Code Snippet: Focus --> The third <td></td> in a table with three columns as in ...

(column1)    (column2)     (column3)  <----Focus of this code snippet.
---------    ----------    ----------

Where column1 is a <label></label> inside of a <td></td>. Where column2 is an <input /> control inside of a <td></td>. Where column3 is an empty <td></td>, filled conditionally based on the errMsgs[] associative array.

Skeleton 1

    <tr>
        <td>
            <label>
            </label>
        </td>
        <td>
            <input />
        </td>
        <td>
<?php
            if($errMsgs['firstName'])
            {
                echo $errMsgs['firstName']; //This element is not from user input. 
            }
?>
        </td>
    </tr>

Skeleton 2

    <tr>
        <td>
            <label>
            </label>
        </td>
        <td>
            <input />
        </td>
        <td>
<?php
            if(isset($errMsgs['firstName']))
            {
                echo $errMsgs['firstName'];  //This element is not from user input.
            }
?>
        </td>
    </tr>

Escaping and coding style issues aside, which skeleton is superior? Which have you used in the past? I want to use the best way.

Answer 1

You could try it.

if($errMsgs['firstName']) will return a notice when the key firstName doesn't exist. So use isset() instead.