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Check for blank Textboxes with PHP


If you remember the script that we wanted to create earlier it was this:

  1. Get the text that a user entered in a textbox on a form
  2. Trim any blank spaces from the left and right of the text
  3. Check that what you have left is not a blank string

So we want to check that the textbox doesn't just contain this "". There has to be something in it, like "Bill Gates". Here's a script that does all three items on our list:


$user_text = trim("Bill Gates");


function display_error_message($user_text) {

if ($user_text == "") {

print "Blank text box detected";

else {

print "Text OK";




Try it out. When you run the script, you should find that Text OK prints. Now change this line:

$user_text = trim("Bill Gates");

to this:

$user_text = trim("");

Run your script again. This time, Blank text box detected should print out. Obviously, we're not getting the text from a textbox on a form, but just simulating the process. If you want to try out a version with all the HTML, here it is. This next script checks two textboxes on a form.

A Script to Check for Blank Text Boxes

Try the script out. But the point is, that we're using the same function to check for blank text boxes. We're not writing the same code over and over. Just call our one function as and when needed.

In the next part, we'll see how to get values back out of functions.

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