Am i using strpos correctly? - php

Question

I am trying to determine whether a word is present within a string of text, then if the word is present, print the relevant string. I'm having issues because this code appears to be working for some of my users but not all of them.
$active = $db->query("SELECT * FROM activity ORDER BY aTIME DESC LIMIT 15");
while($activity = $db->fetch_row($active))
{
$haveact = $activity['activity'];
$username = $r['username'];
if(strpos($haveact, $username))
{
print " <div class='activitydiv'>
{$activity['activity']} &nbsp&nbsp&nbsp&nbsp<small><font color='grey'>
{$activity['aTIME']}</font></small>
</div>";
}
}

Answer 1

Apart from what is suggested in the other answers, I would re-write the whole code to perform the string search in the query. For example like this:
<?php
$active = $db->query("SELECT * FROM (SELECT * FROM activity
ORDER BY aTIME DESC LIMIT 15)
WHERE activity LIKE \"%" . $db->escape($r['username']) . "%\";");
while($activity=$db->fetch_row($active))
{
print "<div class='activitydiv'>
{$activity['activity']} &nbsp&nbsp&nbsp&nbsp<small><font color='grey'>
{$activity['aTIME']}</font></small>
</div>";
}
?>

Answer 2

Please note that strpos returns the position of the found text. So for instance, when the word you are searching for is at the beginning of the the string the function will return '0'. Given that 0 is a false value, when you use the function like you did even though the word is found it will not be true. The correct usage of strpos is:
if (strpos($haystack, $needle) !== false) // Note the type check.
{
// your code...
}
Moreover, this function is case sensitive by default. You can use stripos for case insensitive search.
EDIT
From the manual:
This function may return Boolean FALSE, but may also return a non-Boolean value which evaluates to FALSE
Check the following examples to understand better:
strpos('the quick brown fox jumps over the lazy dog', 'the'); // Returns 0 (false value)
strpos('the quick brown fox jumps over the lazy dog', 'quick'); // Returns 4 (true value)
strpos('the quick brown fox jumps over the lazy dog', 'THE'); // Returns false (case sensitive)

Answer 3

Like Hauke P. mentioned - don not do this with PHP. You WANT to filter the matching rows with your database. If you do not want to use WHERE row LIKE %foo% because you need more power, you can even use REGEX in MYSQL. Just do not process the data with PHP. It is a design failure if you do so.
Check out the MySQL Help files about LIKE, SELECT, and REGEX.
hint: http://www.mysql.com/

Answer 4

strpos has the possibilty to return 0 and FALSE which are basically the same "value"
you need to check type and value like
strpos($haveact,$username) !== FALSE

Answer 5

strpos() returns a boolean FALSE if needle isn't found; and an integer value for its offset in the string if it is found. That offset can be 0, which equates to Boolean FALSE in a loose comparison.
Use
if(strpos($haveact, $username) !== FALSE)

Answer 6

as an alternative you can try php's preg_match function :
if (preg_match("/{$to_search}/" , $subject)) {
// your code to process
}

Answer 7

Another option, I usually use because it's shorter :)
if (strpos($haveact, $username) !== false) {
// In string.
}