Security Issue in my script - Injection

[vividona]

hi friends,

please check my poor script

http://bhl.43i.net

admin account: aaa
admin pass : aaa

if you open any article like:

http://bhl.43i.net/index.php?Artid=16

if I put the sign of single quote ( ' ) after the article number in browse it give this message

http://bhl.43i.net/index.php?Artid=16'

note: I am using this code
I used addslashes() when I insert the text in database
and stripslashes() when I select the text from database

is that correct?

public function ClnArtiSub(){ 
        if( ! get_magic_quotes_gpc() ){ 
            return addslashes(htmlspecialchars( $this->ArtiSub )); 
        } 
    } 
     
    public function StripArtiSub() { 
        if( ! get_magic_quotes_gpc() ) { 
            return stripslashes(htmlspecialchars( $this->ArtiSub )); 
        } 
    } 
     
    public function ClnArtiBod(){ 
        if( ! get_magic_quotes_gpc() ){ 
            return addslashes(htmlspecialchars( $this->ArtiBod )); 
        } 
    } 
     
    public function StripArtiBod() { 
        if( ! get_magic_quotes_gpc() ) { 
            return stripslashes(htmlspecialchars( $this->ArtiBod )); 
        } 
    }