可以在while循环中嵌套for循环吗？

Question

我想这应该是一件容易的事情。我是个新手，你会在我草率的代码中看到这一点，但是我不能让这个for循环在更大的while循环中工作。我得到了一个解析错误，但我已经检查了数百次代码，没有找到缺少的分号或逗号。任何建议都是值得感谢的。

谢谢!

        $result = mysql_query("SELECT `alias`, `max_seats` FROM `rsvp` WHERE `id` = '$id' ");
        $alias = $r['alias'];
        $seats = $r['max_seats'];

        while($r = mysql_fetch_array($result)){
            echo '<h3>Welcome, ' . $alias . '. Please complete your RSVP</h3>';
            echo '<form class="register" method="post">'; 
            echo '<input type="radio" id="responded" name="responded" value="1">Attending (confirm details in the next step)<br />';
            echo '<input type="radio" id="responded" name="responded" value="0"><em><strong>NOT</strong></em> Attending (we\'re sorry you can\'t make it!)<br /><div class="hide" id="hide1">';
            echo '<p>Please select the number of seats you\'d like to confirm (' . $seats . ' seats maximum)</p>';
            echo '<label for="seats">Seats</label>';
            echo '<select name="seats" id="seats">';
            for ($i=1; i=$seats; $i++){
                echo '<option value="' . $i . '">' . $i . '</option>';
            }   
            echo '</select> <input type="text" placeholder="How many Chicken?"></input><br />';
            echo '<input type="text" placeholder="How many Beef?"></input><br /></div>';
            echo '<input type="reset" value="Clear"><input type="submit" value="Submit"></form>';

Answer 1

可以，您可以使用嵌套循环！Click Me!

修复for循环

        for ($i=1; $i <= $seats; $i++){
            echo '<option value="' . $i . '">' . $i . '</option>';
        }

条件$i = $seats不是比较(它是赋值)，只有当$seats为零时才返回false，对于每个条件，它将返回true，并且在每次迭代之后，$i的值将被设置为$seats的值

比较的正确方式可以是

$i != $seats  // not equals
$i == $seats  // equals
$i > $seats  // greater than
$i < $seats  // less than
$i >= $seats  // greater then or equal
$i <= $seats  // less then or equal

        $result = mysql_query("SELECT `alias`, `max_seats` FROM `rsvp` WHERE `id` = '$id' ");
        $alias = $r['alias'];
        $seats = $r['max_seats'];

        while($r = mysql_fetch_array($result))
        {
            echo '<h3>Welcome, ' . $alias . '. Please complete your RSVP</h3>';
            echo '<form class="register" method="post">'; 
            echo '<input type="radio" id="responded" name="responded" value="1">Attending (confirm details in the next step)<br />';
            echo '<input type="radio" id="responded" name="responded" value="0"><em><strong>NOT</strong></em> Attending (we\'re sorry you can\'t make it!)<br /><div class="hide" id="hide1">';
            echo '<p>Please select the number of seats you\'d like to confirm (' . $seats . ' seats maximum)</p>';
            echo '<label for="seats">Seats</label>';
            echo '<select name="seats" id="seats">';
            for ($i=1; $i <= $seats; $i++){
                echo '<option value="' . $i . '">' . $i . '</option>';
            }   
            echo '</select> <input type="text" placeholder="How many Chicken?"></input><br />';
            echo '<input type="text" placeholder="How many Beef?"></input><br /></div>';
            echo '<input type="reset" value="Clear"><input type="submit" value="Submit"></form>';
        }

Answer 2

是的..您可以在while循环中使用for循环。在您的代码中，您缺少一个$ in for循环。应该只是这样。您还需要在for循环中编写一个条件。

for ($i=1; $i==$seats; $i++){

Answer 3

这是正确的，请检查一次.

$result = mysql_query("SELECT `alias`, `max_seats` FROM `rsvp` WHERE `id` = '$id' ");

        while($r = mysql_fetch_array($result)){
            $alias = $r['alias'];
            $seats = $r['max_seats'];
            echo '<h3>Welcome, ' . $alias . '. Please complete your RSVP</h3>';
            echo '<form class="register" method="post">'; 
            echo '<input type="radio" id="responded" name="responded" value="1">Attending (confirm details in the next step)<br />';
            echo '<input type="radio" id="responded" name="responded" value="0"><em><strong>NOT</strong></em> Attending (we\'re sorry you can\'t make it!)<br /><div class="hide" id="hide1">';
            echo '<p>Please select the number of seats you\'d like to confirm (' . $seats . ' seats maximum)</p>';
            echo '<label for="seats">Seats</label>';
            echo '<select name="seats" id="seats">';
            for ($i=1; $i=$seats; $i++){
                echo '<option value="' . $i . '">' . $i . '</option>';
            }   
            echo '</select> <input type="text" placeholder="How many Chicken?"></input><br />';