php.ini changes but not effective in ubuntu

I have solved my question.
there is a syntax error in php.ini in line 109,so the next all syntax not excute

There is a good chance you didn't have permissions to modify the php.ini file. If you just browse to it via a normal folder window and click it Gedit (or whatever your default text editor is) won't be able to open it with write permissions.

You should be able to get away by sudo nano /etc/php5/apache2/php.ini (then your password at the prompt) then changing the variables. Then be sure to Write Out (CTRL O) or make sure you confirm the save on exit.

For anyone wondering why the php.ini modification is not applied even after all directives are fine and restarting the apache on ubuntu, try restarting apache with sudo

sudo service apache2 restart