quick questions

I'm somewhat of a novice with php. I have a script that simply writes a string to a file. But if the string contains " or ' it changes it to \" or \' onee stored in the file (I'm sure it does it to other special characters as well). How can I prevent this?

P.S. I'm using file_put_contents() [php 5 only]. Would it be better to use fopen(), fwrite(), and fclose()?