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plurals

POUnsetting local variables
primarykey
Id
15742721
data
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15742773
AnswerCount
1
ClosedDate
CommentCount
3
CommunityOwnedDate
CreationDate
2013-04-01T11:37:17.463
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2
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2013-04-01T11:41:20.770
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2013-04-01T11:41:20.770
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2203484
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ViewCount
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LastEditorDisplayName
text
Body
There are a couple of examples of this behavior in Code Igniter framework - creating a variable at the beginning of a method, working with it, and before the end of the method, unsetting this variable. Why do they unset them? What's the point? As far as I know, local variables die at the end of the method anyways. Code igniter, from the session class (see last lines): <pre><code>function sess_read() { // Fetch the cookie $session = $this->CI->input->cookie($this->sess_cookie_name); // No cookie? Goodbye cruel world!... if ($session === FALSE) { log_message('debug', 'A session cookie was not found.'); return FALSE; } // Decrypt the cookie data if ($this->sess_encrypt_cookie == TRUE) { $session = $this->CI->encrypt->decode($session); } else { // encryption was not used, so we need to check the md5 hash $hash = substr($session, strlen($session)-32); // get last 32 chars $session = substr($session, 0, strlen($session)-32); // Does the md5 hash match? This is to prevent manipulation of session data in userspace if ($hash !== md5($session.$this->encryption_key)) { log_message('error', 'The session cookie data did not match what was expected. This could be a possible hacking attempt.'); $this->sess_destroy(); return FALSE; } } // Unserialize the session array $session = $this->_unserialize($session); // Is the session data we unserialized an array with the correct format? if ( ! is_array($session) OR ! isset($session['session_id']) OR ! isset($session['ip_address']) OR ! isset($session['user_agent']) OR ! isset($session['last_activity'])) { $this->sess_destroy(); return FALSE; } // Is the session current? if (($session['last_activity'] + $this->sess_expiration) < $this->now) { $this->sess_destroy(); return FALSE; } // Does the IP Match? if ($this->sess_match_ip == TRUE AND $session['ip_address'] != $this->CI->input->ip_address()) { $this->sess_destroy(); return FALSE; } // Does the User Agent Match? if ($this->sess_match_useragent == TRUE AND trim($session['user_agent']) != trim(substr($this->CI->input->user_agent(), 0, 120))) { $this->sess_destroy(); return FALSE; } // Is there a corresponding session in the DB? if ($this->sess_use_database === TRUE) { $this->CI->db->where('session_id', $session['session_id']); if ($this->sess_match_ip == TRUE) { $this->CI->db->where('ip_address', $session['ip_address']); } if ($this->sess_match_useragent == TRUE) { $this->CI->db->where('user_agent', $session['user_agent']); } $query = $this->CI->db->get($this->sess_table_name); // No result? Kill it! if ($query->num_rows() == 0) { $this->sess_destroy(); return FALSE; } // Is there custom data? If so, add it to the main session array $row = $query->row(); if (isset($row->user_data) AND $row->user_data != '') { $custom_data = $this->_unserialize($row->user_data); if (is_array($custom_data)) { foreach ($custom_data as $key => $val) { $session[$key] = $val; } } } } // Session is valid! $this->userdata = $session; unset($session); return TRUE; } </code></pre>
Tags
<php><codeigniter>
Title
Unsetting local variables
singulars
PostAcceptedAnswerId
1. PO
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 PostTypePostTypeId
 PTAnswer
PostParentId
1. This table or related slice is empty.
PostTypePostTypeId
1. PTQuestion
UserLastEditorUserId
1. USSuresh Kamrushi
UserOwnerUserId
1. USuser2203484
plurals
PostLinksPostIdRelatedPostId
1. PL
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 LTLinked
2. PL
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 LTLinked
3. PL
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 LTLinked
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. This table or related slice is empty.
PostsParentIdCreationDate
1. PO
 singulars
 PostTypePostTypeId
 PTAnswer
VotesPostIdCreationDate
1. VO
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 POUnsetting local variables
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 VTUpMod
2. VO
 singulars
 PostPostId
 POUnsetting local variables
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
3. VO
 singulars
 PostPostId
 POUnsetting local variables
 UserUserId
 USsandip
 VoteTypeVoteTypeId
 VTFavorite
CommentsPostId

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