PHP返回 - 初学者错误

I do not know what I'm doing wrong. Perhaps someone could advise me. I'm trying to define seasons and then use the result in index.

...

File with function:

function getCurrentTheme($for_area) {

// Definition of seasons
$spring='spring theme title';
$spring_season=array('03-21',......);
$summer='summer theme title';
$summer_season=array(......);
$autumn='autumn theme title';
$autumn_season=array(......);
$winter='winter theme title';
$winter_season=array(......);

// Today
$current_date=date('m-d');

// So what season is now?
if ($for_area==='some_area') {
    if (in_array($current_date,$spring_season) {
        $theme=$spring;
    }
    else if (in_array($current_date,$summer_season) {
        $theme=$summer;
    }
    else if (in_array($current_date,$autumn_season) {
        $theme=$autumn;
    }
    else if (in_array($current_date,$winter_season) {
        $theme=$winter;
    }
    else {}
}
else if ($for_area==='other_area') {
    // ...
}
else {}

return $theme;

}

...

Index:

$area='some_area';
getCurrentTheme($area);

// And here is the fault. Hope sometimes I will stop being retarded.

echo $theme;

// What should be printed?
summer theme title

Thanks in advance and please try understand my innocence.

You need to store the value, so that you can then echo it:

$area='some_area';
$theme = getCurrentTheme($area);    
echo $theme;

You're not storing the value returned from the getCurrentTheme function. Either store it in a variable and then echo it

$theme = getCurrentTheme($area);
echo $theme;

or simply echo the call without having to use a variable.

echo getCurrentTheme($area);

Your choice!