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PHP

Simon Clay
Simon Clay
3,999 Points
Posted by Simon Clay
Simon Clay
3,999 Points

PHP Functions: Why is it better to return a variable than echo the results?

Randy's 'Build a Simple PHP Application' is great. I've learned so much from it.

With regard to the Functions section, I wonder why it's better to return an variable rather than echo the results within the function?

I have tried to apply the same technique to my own sample code below. My code works as seen here, but when I try to return a variable instead of echoing the results it outputs nothing to the screen.

Can anyone shed any light or improve my code below?

Many thanks.

<?php 
    $products = array();

    $products["1940s-1950s"] = array(
        "name" => "1940's - 1950's",
        "type" => "Club Issues",
        "listing" => "1940s-1950s.htm",
        "section" => "1"
    );

    $products["arsenal"] = array(
        "name" => "Arsenal",
        "type" => "Football Club",
        "listing" => "aresenal.htm",
        "section" => "1"
    );

    $products["aldershot"] = array(
        "name" => "Aldershot",
        "type" => "Football Club",
        "listing" => "aldershot.htm",
        "section" => "1"
    );

    $products["current_season"] = array(
        "name" => "Current Season Programmes (2014/2015)",
        "type" => "",
        "listing" => "2014-15season.htm",
        "section" => "2"
    );




    function getListView($products, $section, $type) {
        echo "<ul>";
        foreach ($products as $product_id => $product) { 
            if (($product["section"] == $section) && ($product["type"] == $type)) {
                echo "<li>";
                echo '<a href="?s=' . $product_id . '">';
                echo($product["name"]);
                echo "</a>, </li>";
            }
        }
        echo "</ul>";
    }


?>


<h2>Section 1</h2>

<h3>Club Issues</h3>
<?php getListView($products,"1","Club Issues") ?>

<h3>Selected Clubs</h3>
<?php getListView($products,"1","Football Club") ?>

<h2>Section 2</h2>
<?php getListView($products,"2","") ?>

2 Answers

Kevin Korte
Kevin Korte
28,149 Points
Kevin Korte
Kevin Korte
28,149 Points

This code would work

<?php 
    $products = array();

    $products["1940s-1950s"] = array(
        "name" => "1940's - 1950's",
        "type" => "Club Issues",
        "listing" => "1940s-1950s.htm",
        "section" => "1"
    );

    $products["arsenal"] = array(
        "name" => "Arsenal",
        "type" => "Football Club",
        "listing" => "aresenal.htm",
        "section" => "1"
    );

    $products["aldershot"] = array(
        "name" => "Aldershot",
        "type" => "Football Club",
        "listing" => "aldershot.htm",
        "section" => "1"
    );

    $products["current_season"] = array(
        "name" => "Current Season Programmes (2014/2015)",
        "type" => "",
        "listing" => "2014-15season.htm",
        "section" => "2"
    );




    function getListView($products, $section, $type) {
        $html = "<ul>";
        foreach ($products as $product_id => $product) { 
            if (($product["section"] == $section) && ($product["type"] == $type)) {
                $html.= "<li>";
                $html.= '<a href="?s=' . $product_id . '">';
                $html.= ($product["name"]);
                $html.= "</a>, </li>";
            }
        }
        $html.= "</ul>";
        return $html;
    }


?>


<h2>Section 1</h2>

<h3>Club Issues</h3>
<?php echo getListView($products,"1","Club Issues") ?>

<h3>Selected Clubs</h3>
<?php echo getListView($products,"1","Football Club") ?>

<h2>Section 2</h2>
<?php echo getListView($products,"2","") ?>

And really the reason why that I can think of is separation of concerns. You keep you logic code from producing any view able content, and you call that logically code from the views, and show it's results. Small applications, this isn't as necessary, which is why it's valid to ask. You could see how though if this site scaled, this could be a problem if you had some functions that had echo's in them, and some functions that returned, it would be hard to keep straight.

Wordpress deals with this by the function name, which is one option. For instance, the_permalink() will echo the URL from the function. get_the_permalink() will only return it. You can see by the name of the function that would make sense.

Simon Clay
Simon Clay
3,999 Points
Simon Clay
Simon Clay
3,999 Points

That is great Kevin, thank you!

I like the $html.=

I guess that's a shorthand way of writing $html = $html . "<li> etc"; ?

Kevin Korte
Kevin Korte
28,149 Points
Kevin Korte
Kevin Korte
28,149 Points

Yes sir, each line keeps building that html variable. It's a common convention used when a function is building html. I think I originally stole that idea from Wordpress, but I've seen it used elsewhere too. It's handy and familiar.