Class 'Mongo' not found

i have installed mongo in ubuntu server but I got error
"Class 'Mongo' not found"

Resolve:
- add make first :  apt-get install make

sudo pecl uninstall mongo 
sudo pecl install mongo
sudo service apache2 restart

- edit php.ini :

add the following line to your php.ini file:
   

extension=mongo.so

- restart apache:

sudo service apache2 restart