如何从While循环中的最后一个字符串中删除最后一个字符？

Question

I am trying to insert a PHP loop with data from my mysql database inside a Google Charts script.

My result from the database looks like this:

$result = $wpdb->get_results(
    "Query"); 

The loop that I am trying to make is supposed to look like this

['$result',  $result],

And this is what I have come up with so far

$count = 0;
while ($count < count($result)) {
    echo "['" . $result[$count]->dato . "', " . $result[$count]->vaegt . "].<br>";
    $count++;
    }

Which create the string that I am looking for. The problem is that I need to remove the comma from the last string in the loop.

I have tried the function LTRIM, but it removes it from every string in the loop, not just the last.

What would be the best solution to fix this problem?

Answer 1

First off, don't use count() in a loop. It may look convenient, but it's slower as it performs the operation over and over on each iteration. Assign the count result to a variable first. And personally, I would use a for() loop here.

Secondly, you need to use a condition inside the loop. Rather than trying to remove the last comma just run a check on the iteration count, if it's not last then add a comma.

$count = count($result);
for($i = 0; $i < $count; $i++)
{
    echo ....
    if $i < $count
    {
        echo ", ";
    }
}

Answer 2

You can use json_encode, I think it will give you the kind of output you want.

Like this:

$arr = array();

foreach ( $result as $res ) {

    $dato = $res->dato;
    $vaegt = $res->vaegt;

    $arr[$dato] = $vaegt; 

}

$output = json_encode($arr);

echo $output;

This is going to output:

{"dato1":"vaegt1","dato2":"vaegt2", etc...}