for loop check if empty value in PHP

Question

In PHP I have 3 fields. I want to only output fields that have a value using a loop.

$field_1 = "john";
$field_2 = "";
$field_3 = "jack";



for($a = 1; $a <= 3; $a++)
{
$fieldOutput =  '$field_' . $a;
    
    if (!empty($fieldOutput)) {
    echo $fieldOutput;
}
}

My desired output is: john jack

...but the code above outputs $field_1. I'm looking to output the actual value of the field though.

...how please can I amend the for loop code to achieve that. Thanks

Answer 1

Replace the line $fieldOutput = '$field_' . $a; with $fieldOutput = ${"field_$a"};. See the PHP documentation for variable variables.