How can I filter text field by keywords through php $_POST

I have a form having text fields and text areas. I want to filter keywords , for example I have a contact form if some use to fill the form and clicks on submit, the form should be submited as normal, at this stage the php code should analyse that the name field should not contain any keywords which is already instructed to php code and if that keyword in the feild or text area found, it should return an error instead of send an email to the webmaster.


Any help will be appreciated and thanks in advance.

 

This should give you a head start

<?php
$word_not_aloud = array("word", "word1", "word2");

if (in_array($_POST['name'], $word_not_aloud))
{
	echo "Error can not use that word.....";	
} else
{
	// continue with submitting the email	
}
?>

PHP:

 

Thanks Lee, You really helped me but please make little alteration in the code, let me explain it,

This code is okay if I use to submit only one keyword same as in the array which is already specified, but when i uses more keywords and in among the text there is a spam keyword , it is unable to findout.

for example, there is value of $_POST['name'] = "This is key word."
In the above line you have noticed that there a spam keyword "word" I need a code which will point out and find automaticaly from a line or paragraph and should filter it.

Thanks, hope you can understand me. waiting for reply.

 

I'm confused what your trying to ask.

If the keyword is in $_POST['name'], regardless if a sentence or one word it wont display it.