The easiest way to add php to your posts is to install ProThemesWP PHP Shortcode plugin and then use its [php] shortcode.
Here is a very simple example using the [php] shortcode. The source code for the example is below the example.
This website is called ProThemesWP
[php] //The name of this website echo '<p>This website is called "' . get_bloginfo( 'name' ) . '"</p>';
Here is a complex example that shows the php reading data entered in a form.
[php] //Create a form that submits its data to this post echo '<form action="' . get_the_permalink() . '" method="POST"> <p><label for="text-value">Please enter a value and click submit to see the php working:</label> <input type="text" name="text-value" id="text-value" /> </p> <p><input type="submit" value="Submit" /></p> </form>'; //If the form has been submitted then display the text value that was entered. if( isset( $_POST['text-value' ] ) ) : echo '<p>The text value you entered was "' . esc_html( $_POST['text-value'] ) . '"</p>'; endif; [/php]
PHP can be placed inline in posts, pages and custom post types by installing ProThemesWP PHP Shortcode and using the shortcode [php].