can this this strlen argument be used for validation? - php

Question

I am new to PHP. My problem is I need the input to validate to a minimum 20 character input and return the last nine. Can anybody tell me if my argument is close to working and if not what do I need to do?
if (!empty($_POST['usen']) ||
strlen($usen['usen'] >= 20 )) {
$switch = substr($usen, -9, 9); // returns last nine of sentence
$output_form=false;
} else {
$error_text .="<p><span class='error'>*<strong>A Sentence of 20 char is required .</strong></span></p>";
$output_form=true;
}

Answer 1

You have several syntax problems and variable-naming problems. Your code should be:
if (!empty($_POST['usen']) && // || should be &&; the || doesn't make sense here
strlen($_POST['usen']) >= 20 ) { // You had $usen['usen'] and an incorrectly placed )
$switch = substr($_POST['usen'], -9); // again, this should be $_POST['usen'], not $usen. The third parameter is unnecessary here.
$output_form = false;
} else {
$error_text .= "<p><span class='error'>*<strong>A Sentence of 20 char is required .</strong></span></p>";
$output_form = true;
}
The key points:
You're using the wrong boolean operator. !empty($x) || strlen($x) >= 20 doesn't make sense. It should be &&, not ||. If you have a non-empty value for $_POST['usen'], then !empty($_POST['usen']) is true. But because you had a || in your if conditional, this meant the if block always executed for non-empty values, never the else block. You only want the if to execute if the value is non-empty and at least 20 characters.
Your variable is $_POST['usen'], but your code referred to $usen['usen'] and $usen, which are incorrect.
You had strlen($usen['usen'] >= 20) where you should have strlen($_POST['usen']) >= 20. Both the variable name and the ) placement were incorrect.

Answer 2

To get the last 9 characters of $usen['usen'] use
$switch = substr($usen, -9);

Answer 3

if (!empty($_POST['usen']) ||
strlen($_POST['usen']) >= 20 ) { // changed condition
$switch = substr($usen, -9, 9); // returns last nine of sentence
$output_form=false;
} else {
$error_text .="<p><span class='error'>*<strong>A Sentence of 20 char is required .</strong></span></p>";
$output_form=true;
}
The if-condition has two issues in second part
You use $usen['usen'] but i think it schould be $_POST['usen'] (see also comment by #Ed Cottrell)
The closing bracker from method-call strlen has to be after the param

Answer 4

if (!empty($_POST['usen']) &&
strlen($_POST['usen'] )>= 20 ) { //condition change
$switch = substr($_POST['usen'] ,-9); // returns last nine of sentence
$output_form=false;
} else {
$error_text .="<p><span class='error'>*<strong>A Sentence of 20 char is required .</strong></span></p>";
$output_form=true;
}
To get last 9 charcters , you can use substr(string, -9);