Calling a function from functions.php in custom page/ blog post

Question

Is it possible to call a function from functions.php in custom page or blog post?

I put simple function in functions.php:

function testTest()
{
echo "Test";
}

And called it from the page:

<?php testTest();?>

But it doesn't work. Do I need to make a plugin to use simple function like that inside one chosen custom page?

Thanks for your answer, Mary

Answer 1

You could use add_shortcode if you want to use it within the editor.

function footag_func() {
    return "Test";
}
add_shortcode( 'footag', 'footag_func' );

And then use [footag] in your editor.

Or

Use code like this in functions.php and add a conditional tag

add_action( 'loop_start', 'your_function' );
function your_function() {
if ( is_singular('post') ) {
    echo 'Test';
    }
}

or

Create a function in functions.php

function your_function() {
return 'Test';

}

And then use this in your template

echo your_function();

Answer 2

You can quickly create a quick shortcode for doing that.

add_shortcode( 'test_shortcode', 'my_test_callback' );

Then, in the callback function you do this:

function my_test_callback() {
    //start adding the echoed content to the output buffer
    ob_start();

    //run your code here - in this case your testTest() function
    testTest();

    //return the output buffer
    //NOTE: directly echoing the content will give unexpected results
    return ob_get_clean();
}

Then, in your content pages you just add [test_shortcode] and it will run your PHP function.

For a better view on shortcodes here are some useful links:

Official Shortcode API

A nice tool for creating shortcodes

An article I wrote on how to build shortcodes