Use of Addslashes and Stripslashes Function in PHP

introduction
The addslashes() function is used to add backslashes [\] to data submitted from your forms. This keeps the input MySQL (and other coding languages) friendly. What this means is that addslashes() would change:
I'm Vinod
to:
I\'m Vinod
This function controls SQL injection; in other words you pass a special character, for example:
 
$fname = $_POST[fname];
$sql="insert into user(fname) value($fname)";
x=(fname)value('Ram's');
This form is called SQL injection. Already (Magic_Quates_GPC)= On otherwise go to PHP ini setting GPC means G for GET, P for POST, and C for COOKIES.
Syntax

addslashes($string_data)

Example

php

$x="ram's"."
"."
";

echo addslashes($x);

?>

php

$str = "Who's vinod?"."
"."
";

echo $str . " This is not safe in a database query.
"."
";

echo addslashes($str) . " This is safe in a database query.";

?>

Output

The stripslashes() function is used to remove backslashes from data. One use of this function is to display data that addslashes() has been applied to. What this means is that stripslashes() would change:

I\'m very Powerful

into:

I'm very powerful

Using stripslashes() after mysql_real_escape_string

Syntax

stripslashes(string)

Note This function can be used to clean up data retrieved from a database or from an HTML form.

I have been reading most recently about prevention of SQL injection and I am trying to develop some sense of understanding among the various functions so that I can learn the basics.

I have read about mysql_real_escape_string and I understand that it is basically escaping characters which it deems "special" so that it is not confused for SQL syntax?

Example

 php

 $said = 'Who said \"Live long and prosper\"?'."
"."
";

;

 print stripslashes($said);

 ?>

 php

echo stripslashes("Who\'s Sharad?");

?>