为什么代码在空函数内部工作但不在其中？

时间：2014-07-24 03:32:21

标签： php function definition defined

我正在为学校开展一个项目，主要是数据管理和演示。我有一段很长的代码需要复制并粘贴到项目的不同部分，所以我想我会把它变成一个函数。我可以将在函数外部工作的代码复制并粘贴到一个空函数中，它不会产生代码在函数外部生成的效果（但不会导致错误）。这是我第一次在php中使用一个函数，看起来很简单，但我无法让它工作。

以下是有效的代码：

<?php

//function display_question($problem_id, $slide_num, $attempt, $admin_id, $result){

//}

include('header.php');
$result = "";
if(isset($_POST['problem_id'])){
    if (!isset($_SESSION['slide']) || empty($_SESSION['slide'])){
        $_SESSION['slide'] = 1;
    }
    $slide_num = $_SESSION['slide'];
    $problem_id = $_POST['problem_id'];
    $admin_id = $_SESSION['user_id'];
    if (!isset($_SESSION['phase']) || empty($_SESSION['phase'])){
        $_SESSION['phase'] = 1;
    }
    $phase = $_SESSION['phase'];
    if($phase == 1){              //show problem attempt#1
        $attempt = 1;
    }elseif($phase == 2){         //graph attempt#1

    }elseif($phase == 3){         //match Students into groups

    }elseif($phase == 4){         //show problem attempt#2
        $attempt = 2;
    }elseif($phase == 5){         //graph attempt#2

    }else{
        $result = 'phase Error';
    }
    //display_question($problem_id, $slide_num, $attempt, $admin_id, $result);
    $update = mysql_query("UPDATE users SET active=1, slide_id='$problem_id', attempt='$attempt' WHERE id='$admin_id'");
    $query = mysql_query("SELECT * FROM problem WHERE id='$problem_id'");

    if($update && $query){

        $row = mysql_fetch_row($query);
        $topic = $row[2];
        $problem = $row[3];
        $solution_a = $row[4];
        $solution_b = $row[5];
        $solution_c = $row[6];
        $image = $row[7];


        if(!empty($image)){
            $result = 'Admin ID: '.$admin_id.'</br><div align="right">Slide '.$slide_num.'</div>
                    Attempt #: '.$attempt.'
                    <h1>'.$topic.'</h1>
                    <img src="'.$image.'" width="500"/>
                    <h2>'.$problem.'</h3>
                    <h3><ol type="A">
                        <li>'.$solution_a.'</li>
                        <li>'.$solution_b.'</li>
                        <li>'.$solution_c.'</li>
                    </ol></h3>';

        }else{
            $result = 'Admin ID: '.$admin_id.'</br><div align="right">Slide '.$slide_num.'</div>
                    Attempt #: '.$attempt.'</br>
                    <h1>'.$topic.'</h1>                         
                    <h2>'.$problem.'</h3>
                    <h3><ol type="A">
                        <li>'.$solution_a.'</li>
                        <li>'.$solution_b.'</li>
                        <li>'.$solution_c.'</li>
                    </ol></h3>';

        }
    }else{
        $result = "Error";
    }

    $result .= ' </br>


        <div id="outer"><div class="inner"><form action="slide.php" method="post">
        <input type="number" value="'.$id.'" hidden="hidden" name="problem_id"/>
        <input type="submit" value="Prev Slide"  class="submit"/>
        </form></div>
        <div class="inner"><form action="slide.php" method="post">
        <input type="number" value="'.$id.'" hidden="hidden" name="problem_id"/>
        <input type="submit" value="Next Phase" class="submit"/>
        </form></div>
        <div class="inner"><form action="slide.php" method="post">
        <input type="number" value="'.$id.'" hidden="hidden" name="problem_id"/>
        <input type="submit" value="Next Slide"  class="submit"/>
        </form></div></div>';

} else {
    $result = "problem_id not set";
}
?>
<!DOCTYPE HTML>
<html>
<title>Presentation</title>
<link rel="stylesheet" type="text/css" href="css/header.css">
<style type="text/css">
div.main{
width: 500px;
margin-top: 25px;
margin-left: auto;
margin-right: auto;
padding: 20px;  
background-color: white;
border: 2px solid black;
border-radius: 5px;
}
#outer{
    width:100%;
    text-align: center;
}
div.inner{
    display: inline-block;
}
form.problem> input{
font-size: 1.1em;
margin-top: 10px;
}
form.nav{
font-size: 1.1em;
margin-top: 10px;
display: inline;
}
input.submit{

width: 120px;
height: 40px;
color: white;
background-color: green;
border: none;
border-radius: 5px; 
margin-top: 25px;
}
input.submit:hover{
background-color: #006600;
}
</style>
</head>
<body>

    <div class="main">
        <?php echo $result;?>
    </div>
</body>
</html>

这是代码副本并粘贴到不起作用的函数中：

<?php

function display_question($problem_id, $slide_num, $attempt, $admin_id, $result){
    $update = mysql_query("UPDATE users SET active=1, slide_id='$problem_id', attempt='$attempt' WHERE id='$admin_id'");
    $query = mysql_query("SELECT * FROM problem WHERE id='$problem_id'");

    if($update && $query){

        $row = mysql_fetch_row($query);
        $topic = $row[2];
        $problem = $row[3];
        $solution_a = $row[4];
        $solution_b = $row[5];
        $solution_c = $row[6];
        $image = $row[7];


        if(!empty($image)){
            $result = 'Admin ID: '.$admin_id.'</br><div align="right">Slide '.$slide_num.'</div>
                    Attempt #: '.$attempt.'
                    <h1>'.$topic.'</h1>
                    <img src="'.$image.'" width="500"/>
                    <h2>'.$problem.'</h3>
                    <h3><ol type="A">
                        <li>'.$solution_a.'</li>
                        <li>'.$solution_b.'</li>
                        <li>'.$solution_c.'</li>
                    </ol></h3>';

        }else{
            $result = 'Admin ID: '.$admin_id.'</br><div align="right">Slide '.$slide_num.'</div>
                    Attempt #: '.$attempt.'</br>
                    <h1>'.$topic.'</h1>                         
                    <h2>'.$problem.'</h3>
                    <h3><ol type="A">
                        <li>'.$solution_a.'</li>
                        <li>'.$solution_b.'</li>
                        <li>'.$solution_c.'</li>
                    </ol></h3>';

        }
    }else{
        $result = "Error";
    }
}

include('header.php');
$result = "";
if(isset($_POST['problem_id'])){
    if (!isset($_SESSION['slide']) || empty($_SESSION['slide'])){
        $_SESSION['slide'] = 1;
    }
    $slide_num = $_SESSION['slide'];
    $problem_id = $_POST['problem_id'];
    $admin_id = $_SESSION['user_id'];
    if (!isset($_SESSION['phase']) || empty($_SESSION['phase'])){
        $_SESSION['phase'] = 1;
    }
    $phase = $_SESSION['phase'];
    if($phase == 1){              //show problem attempt#1
        $attempt = 1;
    }elseif($phase == 2){         //graph attempt#1

    }elseif($phase == 3){         //match Students into groups

    }elseif($phase == 4){         //show problem attempt#2
        $attempt = 2;
    }elseif($phase == 5){         //graph attempt#2

    }else{
        $result = 'phase Error';
    }
    display_question($problem_id, $slide_num, $attempt, $admin_id, $result);


    $result .= ' </br>


        <div id="outer"><div class="inner"><form action="slide.php" method="post">
        <input type="number" value="'.$id.'" hidden="hidden" name="problem_id"/>
        <input type="submit" value="Prev Slide"  class="submit"/>
        </form></div>
        <div class="inner"><form action="slide.php" method="post">
        <input type="number" value="'.$id.'" hidden="hidden" name="problem_id"/>
        <input type="submit" value="Next Phase" class="submit"/>
        </form></div>
        <div class="inner"><form action="slide.php" method="post">
        <input type="number" value="'.$id.'" hidden="hidden" name="problem_id"/>
        <input type="submit" value="Next Slide"  class="submit"/>
        </form></div></div>';

} else {
    $result = "problem_id not set";
}
?>
<!DOCTYPE HTML>
<html>
<title>Presentation</title>
<link rel="stylesheet" type="text/css" href="css/header.css">
<style type="text/css">
div.main{
width: 500px;
margin-top: 25px;
margin-left: auto;
margin-right: auto;
padding: 20px;  
background-color: white;
border: 2px solid black;
border-radius: 5px;
}
#outer{
    width:100%;
    text-align: center;
}
div.inner{
    display: inline-block;
}
form.problem> input{
font-size: 1.1em;
margin-top: 10px;
}
form.nav{
font-size: 1.1em;
margin-top: 10px;
display: inline;
}
input.submit{

width: 120px;
height: 40px;
color: white;
background-color: green;
border: none;
border-radius: 5px; 
margin-top: 25px;
}
input.submit:hover{
background-color: #006600;
}
</style>
</head>
<body>

    <div class="main">
        <?php echo $result;?>
    </div>
</body>
</html>

变量$ result除了之后添加的内容外，没有打印任何内容。从我读到的，函数args默认传递给byval所以我不认为这是问题，我已经检查了变量的所有名称，以确保它们在函数中定义或传递到函数中，并通过我能看到的他们是。我不知道还有什么可以寻找的。它可能很容易让我看起来很愚蠢，但我是php的新手，所以请帮助我。

2 个答案:

答案 0 :(得分：1)

您没有将结果作为参考传递。

你需要像这样定义你的函数：

function display_question($problem_id, $slide_num, $attempt, $admin_id, &$result)
                                                                        ^

答案 1 :(得分：0)

如果您希望函数修改它，则必须通过引用传递$ result。现在，您声明函数的方式（函数display_question（$ problem_id，$ slide_num，$ attempt，$ admin_id，$ result））是按值传递的，用于所有参数。试试这个：

function display_question($problem_id, $slide_num, $attempt, $admin_id, &$result)

另请阅读： http://php.net/manual/en/language.references.pass.php

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