Wordpress函数= 0

Question

i'm a absolute noob with php coding and I guess after several laughs, the solution is really simple for a professional. I coded a simple average-calculation for the category.php of my wp-template and it works perfectly but I heard that it's the much better way to split design and function and so I tried to convet this to a template function:

<?php

$total = 0;
$count = 0;

foreach($posts as $post)
{
     if(get_field('weight')){ // If we have a value add it to the total and count it
        $total += get_field('weight');
        $count++;
     }
}

$Average = $total / $count; 
echo $Average;       
?>

The result is always "0" because I guess he pulls the variable from above and skips the foreach-procedure. But why?

function averageit()
{
$total = 0;
$count = 0;
foreach($posts as $post)
    if(get_field('weight'))
    $total += get_field('weight');
    $count++;
    $Average = $total / $count;

  echo $Average; 
}

I hope somebody is able to help me. Thank you in advance!

Answer 1

Your problem is likely to be one of variable scope. The "scope" of a variable is the section of code where that variable "exists", if you will.

In your case, consider your foreach loop, looping through items in the '$posts' variable. Where is the $posts variable declared? I suspect that at the point of the function running, that variable doesn't exist, so the loop is not being executed at all.

I'd suggest the following amendments to your function:

function find_average_weight($posts)
{
    $total = 0;
    $count = 0;
    foreach($posts as $post)
    {
        if(get_field('weight'))
        {
            $total += get_field('weight');
            $count++;
        }
    }
    $Average = $total / $count;
    return $Average; 
}

There's a few changes here.

• While writing the function out I realised your foreach loop had no braces. This can cause issues of readability and indeed make the logic work incorrectly, so I put them in :)
• I added an parameter to the function to pass the required "$posts" variable in.
• I changed the function name to be slightly more descriptive, though not knowing the exact application I may be off the mark here, so take the suggestion with a grain of salt.
• I altered your function to return a value, which you can then do whatever you wish with. This makes the function a little more agnostic regarding what your intentions are - perhaps at some point you will want to find the average of these posts without outputting the results?

To use the new function and output the result, you could now write a line like this:

echo(find_average_weight($posts));