if语句何时回显html

Question

So I'm trying to generate select values with a loop. The issue here is that I can't use an if statement. I could set pieces of string together with a number of if statements, but that seems like an odd solution.

<select name="test">
              <option disabled selected> -- Select an industry -- </option>
              <?php 
                $numberOfIndustries = count($industryOptions); //industryOptions is an array
                for($i = 0; $i <= $numberOfIndustries; $i++) {
                  echo "<option" . if (isset($_POST['test']) == true && $_POST['test'] == $industryOptions[$i]) { .  "selected='true'" . }; . "value=" . $industryOptions[$i] . ">" . $industryOptions[$i] . "</option>";
                }
              ?> 
</select>

Answer 1

You cannot use the . (dot) to concat IF clause - only strings. Instead, you can use the ternary operator.

So your echo call should look as follows:

echo "<option " . 
     (isset($_POST['test']) && ($_POST['test'] == $industryOptions[$i]) ? "selected='true' " : ""). 
     "value=" . $industryOptions[$i] . ">" . $industryOptions[$i] . "</option>";