在PHP7上调用未定义函数json_encode(),ctype_digit(),ubuntu [关闭]

i use Yii2 , OS ubuntu 16.0.4 , PHP7 , Apache , MySql

i think this problem from php7

how to enable or install json_encode for php and ctype_digit for mysql?

i have this error:

Call to undefined function yii\web\json_encode()

Call to undefined function yii\db\mysql\ctype_digit()

phpInfo:

Configuration File (php.ini) Path   /etc/php/7.0/apache2
Loaded Configuration File   /etc/php/7.0/apache2/php.ini
Scan this dir for additional .ini files     /etc/php/7.0/apache2/conf.d
Additional .ini files parsed    /etc/php/7.0/apache2/conf.d/20-mbstring.ini 

about json i only find this on phpinfo:

JSON    Jakub Zelenka, Omar Kilani, Scott MacVicar 

Enable json encode in php.ini file in /etc/php/php.ini. In this case, you'd need to uncomment the 'extension=json.so' line.