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F
future-architect
Known Participant
May 23, 2012
Question

finding number in a string

  • May 23, 2012
  • 2 replies
  • 3131 views

I am trying to find a number in a string from my database to replace it.  Here is my funciton:

function findUserID($friendsString, $userToFind){

          echo $friendsString . " " . $userToFind;

          $pos = strpos($friendsString,$userToFind);

          if($pos){

                    return true;

          }

          return false;

}

it returns "25,29 25".  How can it not find 25 in that string?

This topic has been closed for replies.

2 replies

B
bregent
Participating Frequently
May 24, 2012

Because string positions start at 0, not 1. Read the warning and solutions here: http://www.php.net/manual/en/function.strpos.php

F
future-architectAuthor
Known Participant
May 24, 2012

I understand that it starts at 0.  it should still work.  i had it working before.  i must've changed something. 

here is my code for passing to the function:

$query = mysql_query("SELECT friends, pendingFriendRequest

FROM members

WHERE username = '$userID'");

if (mysql_affected_rows() > 0) {

          $row = mysql_fetch_array($query) or die(mysql_error());

          $friends = $row['friends'];

          $pendingFriends = $row['pendingFriendRequest'];

}

// If the user exists in the waiting list, then

//continue (we must confirm that they are first by checking the DB

$test = findUserID($pendingFriends, "25");

if($test){

          // If they are, then continue to add them

          $test = confirmFriend($pendingFriends, "25");

          if($test) {

                    echo "<br />You have confirmed " . findUserName(24) . "as a friend.";

          } else {

                    echo "<br />Error: Please try again, or contact us.";

          }

} else {

          echo "<br />Error: You either have this person as a friend already, or there was an internal error.";

}

B
bregent
Participating Frequently
May 24, 2012

Oh, so if it finds it or not, it automatically returns the value?   i can't overide it with "return true/false"?


>Oh, so if it finds it or not, it automatically returns the value? 

Let me try to explain again. The function strpos() returns two types of values. It returns an integer value if the string is found. It returns the boolean value FALSE if the string is not found. It never returns the boolean value TRUE. If the string is found in position zero, it returns the integer value zero. Zero is not a boolean value, but in php and many other languages, zero is evaluated as boolean FALSE.

>i can't overide it with "return true/false"?

I'm not sure what you mean. You have to treat the returned value in such as way that integer zero will not be evaluated as FALSE. Use the "===" operator for this. Or in the case of replacing the code you have, use the "!==" operator

if($test !== false)

If strpos() did not find the string, $test will equal false and the expression above will evaluate false.  If it returns any integer, the expression will evaluate as true.

Rob Hecker2
Rob Hecker2
Legend
May 24, 2012

Is there are reason you are not doing this with just an UPDATE query? Something like the following:

UPDATE 'table' SET 'column' = REPLACE('column', '25' 'replacementdata')

F
future-architectAuthor
Known Participant
May 24, 2012

thanks for this, but first i have to check if the user exists first in the field.

Rob Hecker2
Rob Hecker2
Legend
May 24, 2012

So it's not just replacing everywhere it encounters 25? At any rate, even if I don't quite understand what you are trying to do,  it still seems like the best way to do this is all in MySQL, not PHP.

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