How to write php code in your post,page or text widgets

1- for write code in your wordpress posts you need to downlode and install the following plugin.
 https://wordpress.org/plugins/php-code-for-posts/
2- After that open the plugin from wordpress dashbord.
3-Add new button
 for Example wordpress base url.
fill the field like
Change your code's name= Base url
Change the short description=Base url
about your code
Change the actual code
Remember to open your PHP code with <?php= <?php
echo site_url();
?>

4- click the button update this code.

5- you will gat a short code like this "[php snippet=1]".

6- use this shortcut code where you want your php code in post,page or text widgets