Add the text in between two text using php file handling -

my question have file handling in php.in file handling have create file,write file , update file.if create text file using php file handling , write file hello guys , close file.i want update file time while update file want add text in between hello , guys.for example hello hii guys.or guys word overwrtten speed.hello speed.

thanks please me

you can append text @ last using below link or other option http://php.net/manual/en/function.file-put-contents.php