php - can't use function return value in write context - error in line 7 -

i can't understand issue. know question repeated not able understand issue in code.

<?php //review box display function sch_ninja_display_review($postcontent){     global $post;     $review=$post;     if(get_post_meta($review->id,'review_show',true)=="on"){        if(!empty(get_post_meta($review->id,'review_price',true))){           $price='price:'.get_post_meta($review->id,'review_currency',true).get_post_meta($review->id,'review_price',true);        } 

line 7: if(!empty(get_post_meta($review->id,'review_price',true))){

empty() php language construct , supports variables , expressions, , no function calls arguments.

you have assign result of call variable first , empty check so:

$reviewprice = get_post_meta($review->id,'review_price',true); if(!empty($reviewprice)){