Question

I am having a problem understanding why this part of my code is causing a memory leak:

for($i=0; $i<count($values); $i++){
        $values[$i] = addslashes($values[$i]);
}

To put the code in context, i have a previously built array called values, which has all the values to be inserted into a database. all the fields are strings so i need to escape all of them and for this application addslashes or mysql_real_escape_string are a good choice imo.

Now the strange thing is that as soon as i added the part shown above, i get a message like this:

PHP Fatal error:  Allowed memory size of 134217728 bytes exhausted (tried to allocate 24 bytes)

I understood that this generated a memory leak but i don’t know why.

Digging in, i commented out the only line in the for loop, leaving the for statement just for curiosity, and the leak is gone. Any ideas what could this possibly mean?

PS: The strings are all UTF8 encoded, could that be a problem?

EDIT:

The array contains something like this :

Array ( 
    [dossier] => 002A 
    [permis] => 
    [adresse] => 18, rue Bellevue
    [ville] => Ste-Anne-des-Lacs (Québec)
    [province] =>
    [code_postal] => J0R 1B0
    [numero_centrale] => N/A
    [routes] => De la Gare, droite chemin Avila jusqu'au bout et droite chemin Ste-Anne-des-lacs sur 1,8 km et droite sur Bellevue.
) 

Answer 1

Your array has string keys, but you are checking/assigning numeric keys. As @nickb notes, each time you add a numeric key, count($values) increases by one, so you have an infinite loop. Hence the memory exhaustion.

Check with a debugger, or better yet, switch to a foreach loop or one of the array_* functions (array_walk(), array_map(), etc. depending on what you are trying to do).

@Jeremy correctly points out that you should not be using addslashes() to escape your strings. Look at mysqli_real_escape_string() (as he suggests), or better yet, consider using PDO if you can.