printf

You’ve probably seen code in your files which looks like this:

printf('%s World', $var );

This code includes a function named printf() which in most cases is more efficient than using the echo or print functions.

To learn more about using PHP code in WordPress & Genesis, you’ll need to understand how the printf function works.

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Printf generally includes a % percentage sign with an s for string like this:

%s

Printf can be used in replace of print or echo so rather than use this:

echo "Hello World";

or

print( 'Hello World' );

Instead, you can use printf like this:

printf('%s World', "Hello" );

These % percentage signs with a s work like placeholders which are converted when the code is executed. In the above case %s is replaced with the text Hello.

Here’s the full working code you can test in your child themes functions file:

add_action('loop_start','printf_example1' );
function printf_example1() {<br />
printf('%s World', 'Hello' ); 
}

You can then replace your text ‘Hello’ with a variable so the value for your $text variable is now equal to Hello:

$text = 'Hello';

The full working code you can test in your child themes functions file would be this:

add_action('loop_start','printf_example2');
function printf_example2() {<br />
$text = 'Hello';
printf('%s World', $text ); 
}

In WordPress themes, you’ll find code which uses printf which you can paste into your child themes functions.php file to see how it works:

add_action('loop_start','printf_example3');
function printf_example3() {<br />
printf( '<a href="%s">' . esc_html__( 'Your link text here', 'text-domain' ) . '</a>', 'https://example.com' ) ); 
}

The code above uses printf with one instance of %s which is replaced by the URL https://example.com when the function is executed.

The above code can also be written like this:

add_action('loop_start','printf_example4');
function printf_example4() {

$link = esc_url( get_permalink() );
$text = "Value for Your Text Variable";

printf( '<a href="%s">%s</a>', $link, $text ); 
}

In this case, we have replaced the URL with a variable named $link. We have also replaced the text with a variable named $text.

The value for the $link variable is equal to the posts permalink rather than the example.com URL and the value for the $text variable is equal to the text.

You’ll also notice each parameter in the string is separated by a comma like this:

$link, $text

When the code executes, the 1st placeholder %s is replaced with the 1st parameter which in this case is the $link variable which equals get_permalink();

After the 1st placeholder is replaced, the 2nd, 3rd and so on are replaced step by step in the order they occur in the string, separated by a comma.

You can also write the code as follows:

add_action('loop_start','printf_example5');
function printf_example5() {

$text = "Value for Your Text Variable";

printf( '<a href="%s">%s</a>', esc_url( get_permalink() ), $text ); 
}

This way the 1st parameter is equal to the get_permalink function rather than the value for the $link variable as in example 4.

printf & sprintf

Printf is used to output the formatted string. Example:

add_action('loop_start','printf_example6' );
function printf_example6() {<br />
    printf('%s World', 'Hello' ); 
}

Sprintf is returned as the value for a variable to be used later then the variable can be output using echo or printf. Example:

add_action('loop_start','printf_example7' );
function printf_example7() {<br />
$output = sprintf('%s World', 'Hello' ); 
echo $output;
}

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