PHP 7.3 not installing on Ubuntu 16.04 LTS

I am trying to install php 7.3 over ubuntu 16.04. but its always shows

Reading state information... Done
E: Unable to locate package php7.3
E: Couldn't find any package by glob 'php7.3'
E: Couldn't find any package by regex 'php7.3'

i have tried everything available over net like following

LC_ALL=C.UTF-8 add-apt-repository ppa:ondrej/php

this also

add-apt-repository ppa:ondrej/php

with sudo access.

sudo apt install php7.3 php7.3-common php7.3-cli

nothing is working.

Have you run sudo apt update yet? If you haven't, your system isn't going to know that the PHP 7.3 packages are available.

Run sudo apt update and then try the install commands you were trying.