Search for a specific string within another string with PHP

Question

I need to search a string for any occurances of another string in PHP. I have some code that I've been playing with, but it doesn't seem to be working.

Here is my code:

while (list($key, $val) = each($keyword)) {
  $pos = strpos($location, $val);
  if($pos == false) {
    echo "allow";
    exit;
  } else {
    echo "deny";
    exit;
  }
}

I have tried some of the options below, but it still does not find the match. Here is what I'm searching:

I need to find:*

blah

In:

http://blah.com

Nothing seems to find it. The code works in regular sentences:

Today, the weather was very nice.

It will find any word from the sentence, but when it is all together (in a URL) it can't seem to find it.

It's simpler to use strstr() if you don't actually need the substring position. — mario
– mario, Commented Nov 17, 2010 at 6:59

Asaph · Accepted Answer · 2010-11-17 05:30:16Z

2

When checking for boolean FALSE in php, you need to use the === operator. Otherwise, when a string match is found at the 0 index position of a string, your if condition will incorrectly evaluate to true. This is mentioned explicitly in a big red box in the php docs for strpos().

Also, based on a comment you left under another answer, it appears as though you need to remove the exit statement from the block that allows access.

Putting it all together, I imagine your code should look like this:

while (list($key, $val) = each($keyword)) {
  $pos = strpos($location, $val);
  if($pos === false) { // use === instead of ==
    echo "allow";
  } else {
    echo "deny";
    exit;
  }
}

Update:

With the new information you've provided, I've rewritten the logic:

function isAllowed($location) {
    $keywords = array('blah', 'another-restricted-word', 'yet-another-restricted-word');
    foreach($keywords as $keyword) {
        if (strpos($location, $keyword) !== FALSE) {
            return false;
        }
    }
    return true;
}

$location = 'http://blah.com/';
echo isAllowed($location) ? 'allow' : 'deny';

edited Nov 17, 2010 at 5:30

answered Nov 17, 2010 at 5:09

Asaph

163k25 gold badges204 silver badges204 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Zac Brown Over a year ago

How do I check to see if it is a match, instead of false?

Collectives™ on Stack Overflow

Search for a specific string within another string with PHP

1 Answer 1

Update:

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Update:

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related