如果值为空，则不显示任何内容

Question

On one file I have this code:

if (theForm.lqd_9.value == "")
{
    alert("You have forgotten to specify - Description!");
    theForm.lqd_9.focus();
    return (false);      
    <tr>
       <td class="theadingt" align="center" height="14" width="180">
             <b>Description:<span lang="en-us"><font color="#ff0000">*</font></span></b></td>
        <td class="theading" align="left" height="14" width="545">
    <textarea cols='48' rows='6' name="lqd_9"></textarea></td>
   </tr>

and on the receiving file I have this:

<?php echo $_POST["lqd_9"]; ?>

How can I make the code to not display anything if it's left empty?

Answer 1

You could use methods like isset or empty

<?php 
if(isset($_POST["lqd_9"])){
 echo $_POST["lqd_9"];
} 
?>

OR

<?php 
if(!empty($_POST["lqd_9"])){
 echo $_POST["lqd_9"];
} 
?>

update

It's better to use both as below.

<?php 
if(isset($_POST["lqd_9"]) && !empty($_POST["lqd_9"])){
 echo $_POST["lqd_9"];
} 
?>

PHP isset() vs empty() vs is_null()

Answer 2

Its a best practice to use isset and to escape characters like:

<?php
    if(isset($_POST["lqd_9"]) && trim($_POST["lqd_9"]) !== ""){
        echo htmlspecialchars($_POST["lqd_9"], ENT_COMPAT | ENT_HTML401, 'UTF-8');
    }
?>

Answer 3

if(isset($_POST["lqd_9"]) && $_POST["lqd_9"]){
     ###ALL CODE
}

This simple check will guarantee that there is post data lqd_9 :)

ISSET checks if its set at first time else if you are using it without its set it may throw error. And the second check is checking if lqd_9 is different from FALSE (if its empty its false else its true)

Answer 4

<?= isset(($_POST['lqd_9']) ? $_POST['lqd_9'] : ''; ?>

That said, it's a bad practice to display user provided data without saniting it. You could create a small convenience function that returns sanitized data /ex:

<?php
function sanitize($str) {
    return filter_var($str, FILTER_SANITIZE_STRING);
}
?>

<?= isset($_POST['lqd_9']) ? sanitize($_POST['lqd_9']) : '' ?>

Answer 5

<?php 
   if(isset($_POST['lqd_9']){
       echo $_POST['lqd_9'];
   }
?>