0 not passing a if statement if != 0 ? string compared to string

Question

i am just fixing some form validation, and i seem to have a very odd issue.

$newsletter = $_POST['newsletter']; // value 0 or 1 is passed from form, as "value"
// input type is radiobuttens

then i have a very simple

if ($newsletter != "0" || $newsletter != "1") {
    $error_message .= 'Invalid newsletter?<br />';
}

it does not pass this? i did try:

if ($newsletter != 0 || $newsletter != 1) {

does not pass either, but thats comparing a string to an int as far as i know

What are you trying to accomplish? Edit: What do you get if you echo $newsletter ? That will probably help you answer it yourself — Ryan
– Ryan, Commented May 3, 2013 at 13:36
Im trying to filter the validation and prevent html editing, i have a form with a input type radiobutten newsletter, yes = 1 no = 0, very simple, it gets sent to the form, and i want to filter it and return an error if it does not = 1 or 0 — John DOe
– John DOe, Commented May 3, 2013 at 13:37
I think you need && instead of || in the query - an OR is matched if either side is true, and the number is always going to be a 0 (which matches != 1) or 1 (which matches != 0) — andrewsi
– andrewsi, Commented May 3, 2013 at 13:37

Rene Pot · Accepted Answer · 2013-05-03 13:38:38Z

1

You'll have to change the statement to &&

if ($newsletter != "0" && $newsletter != "1") {

This will check if it is neither 0 nor 1.

answered May 3, 2013 at 13:38

Rene Pot

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Comments

David Schwartz · Accepted Answer · 2013-05-03 13:37:20Z

0

If it's "0", it's not "1". If it's "1", it's not "0". So it will always either not be zero or not be one. No value would pass that test.

You only want to return an error if it's not equal to "1" and it's also not equal to "0".

answered May 3, 2013 at 13:37

David Schwartz

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Ryan · Accepted Answer · 2013-05-03 13:38:18Z

0

Answering the comment, you can just do:

if(!$newsletter) { $error_message .= 'Invalid newsletter?<br />'; }

answered May 3, 2013 at 13:38

Ryan

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Schleis · Accepted Answer · 2013-05-03 13:39:57Z

0

You want an AND comparison. I am assuming that you want to make sure that only a value of 0 or 1 is passed to the script.

if ($newsletter != "0" && $newsletter != "1") {
    $error_message .= 'Invalid newsletter?<br />';
}

Since 0 != 1 either of side of your OR condition was true. So this always passed.

answered May 3, 2013 at 13:39

Schleis

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