为什么所有4.php函数都显示submit - Why are all 4 .php functions displaying with submit?

几周前开始使用.php，并在一本书中发现了这个问题。我有4个不同的按钮，它们将分别调用不同的函数，但目前当我单击单个按钮时，我的所有4个函数都会被调用？需要一点帮助来理解这个。除了电话，一切都很好。对于每个提交按钮，都应该调用不同的函数。我有独立于php代码的html。我看到的是点击一个按钮，函数就会被调用。目前，它正在同时调用所有函数。

HTML:

    <?php 
if (isset($_POST['Sequence1'])) {
    echo Sequence1(); }
    else if (isset($_POST['Sequence2'])) {
        echo Sequence2(); }
        else if (isset($_POST['Sequence3'])) {
            echo Sequence3(); }
            else if (isset($_POST['Sequence4'])) {
                echo Sequence4(); }
?>
<!doctype html>
<html>
<head>
<title>Sequence Test</title>
<link rel="stylesheet" type="text/css" href="q2.css">
</head>
<body>
<form action="q2_process.php" method="post">
<div class="header">
<header><h1>Numeric Sequence Tester</h1></header>
</div>
<div class="prompt">
<h2>Click on a button below to see the sequence</h2>
</div>
<div class="button1">
    <p><button type="submit" formmethod="post" name="Sequence1" value="Sequence1" class= "buttons">Sequence 10 - 2n</button></p>
    </div>
    <div class="button2">
    <p><button type="submit" formmethod="post" name="Sequence2" value="Sequence2" class="buttons">Sequence 4n + 3</button></p>
    </div>
    <div class="button3">
    <p><button type="submit" formmethod="post" name="Sequence3" value="Sequence3" class="buttons">Sequence n*n - 2</button></p>
    </div>
    <div class="button4">
    <p><button type="submit" formmethod="post" name="Sequence4" value="Sequence4" class="buttons">Sequence ar^n; when a-4 r=3</button></p>
</div>
</form>
</body>
</html>
PHP Functions:
    <?php
function Sequence1() {
    $num = 0;
    $result = 0;
    for($i = 0; $i < 9; $i++) {
        $num++;
        $num1 = (2 * $num);
        $result = 10 - $num1;
        echo "When n=${num};   10-2n = 10-2x $num1 = 10 - $num1 = $result  <br>"; }} ?>
<?php function Sequence2() {
    $num = 0;
    $result = 0;
    for($i = 0; $i < 9; $i++) {
        $num++;
        $num1 = (4 * $num);
        $result = $num1 + 3;
        echo "When n=${num};    4n+3 = 4 x $num + 3 = $num1 + 3 = $result <br>"; }}; ?>
<?php function Sequence3() {
    $num = 0;
    $result = 0;
    for($i = 0; $i < 9; $i++) {
        $num++;
        $num1 = ($num* $num);
        $result = $num1 - 2;
        echo "When n=${num};    n*n-2 = $num x $num - 2 = $num1 - 2 = $result <br>"; }}; ?>
<?php function Sequence4() {
    $num = 0;
    $result = 0;    
    for($i = 0; $i < 9; $i++) { 
        $a = 3;
        $r = 2; 
        $num++;
        $num1 = $a * pow($r, $num -1);
        $result = $num1 * 2;
        echo "When n=${num};    $num1 x 2 = $result <br>"; }} ?>
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Sequence Tester</title>
<link rel="stylesheet" type="text/css" href="q2.css">
</head>
<body>
<div class="header">
<header><h1>Sequence Tester</h1></header>
</div>
<!--Create divs to hold each button click-->
<div class="seq1">
<h3>You selected button 1</h3>
<p><?php echo Sequence1(); ?></p>
</div>
<div class="seq2">
<h3>You selected button 2</h3>
<p><?php echo Sequence2(); ?></p>
</div>
<div class="seq3">
<h3>You selected button 3</h3>
<p><?php Sequence3(); ?></p>
</div>
<div class="seq4">
<h3>You selected button 4</h3>
<p><?php Sequence4(); ?></p>
</div>
<div class="home">
<a href="q2_index.html">Back to Homepage</a>
</div>
</body>
</html>

您在这里调用每个函数：

<div class="seq1">
<h3>You selected button 1</h3>
<p><?php echo Sequence1(); ?></p>
</div>
<div class="seq2">
<h3>You selected button 2</h3>
<p><?php echo Sequence2(); ?></p>
</div>
<div class="seq3">
<h3>You selected button 3</h3>
<p><?php Sequence3(); ?></p>
</div>
<div class="seq4">
<h3>You selected button 4</h3>
<p><?php Sequence4(); ?></p>
</div>

这就是为什么所有按钮都已提交的原因。

编辑以回答您关于函数为什么在DOM顶部输出的第二个问题：

DOM顶部的输出是因为您在这里调用php函数：

if (!empty($_POST['Sequence1'])) {
    $v = "button 1";
    Sequence1(); }
else if (isset($_POST['Sequence2'])) {
    $v = "button 2";
    Sequence2();  }
else if (isset($_POST['Sequence3'])) {
    $v = "button 3";
    Sequence3(); }
else if (isset($_POST['Sequence4'])) {
    $v = "button 4";
    Sequence4(); ; }

由于每个函数都是由您定义为"回显"结果，而不是将结果"返回"到变量（请参阅函数描述），因此当您在上面的if/else循环中调用它时，它会在页面顶部附近输出。

已编辑我对您的函数调用进行了一些更改，改为"返回"值，然后将它们显示在正确的div中。试试这个：

    <?php
$v = '';
$j = '';
if (!empty($_POST['Sequence1'])) {
    $v = "button 1";
    $j = Sequence1(); }
else if (isset($_POST['Sequence2'])) {
    $v = "button 2";
    $j = Sequence2();  }
else if (isset($_POST['Sequence3'])) {
    $v = "button 3";
    $j = Sequence3(); }
else if (isset($_POST['Sequence4'])) {
    $v = "button 4";
    $j = Sequence4(); }
?>
<!doctype html>
<html>
<head>
    <title>Sequence Test</title>
    <link rel="stylesheet" type="text/css" href="q2.css">
</head>
<body>
<form action="" method="post">
    <div class="header">
        <header><h1>Numeric Sequence Tester</h1></header>
    </div>
    <div class="prompt">
        <h2>Click on a button below to see the sequence</h2>
    </div>
    <div class="button1">
        <p><button type="submit" formmethod="post" name="Sequence1" value="Sequence1" class= "buttons">Sequence 10 - 2n</button></p>
    </div>
    <div class="button2">
        <p><button type="submit" formmethod="post" name="Sequence2" value="Sequence2" class="buttons">Sequence 4n + 3</button></p>
    </div>
    <div class="button3">
        <p><button type="submit" formmethod="post" name="Sequence3" value="Sequence3" class="buttons">Sequence n*n - 2</button></p>
    </div>
    <div class="button4">
        <p><button type="submit" formmethod="post" name="Sequence4" value="Sequence4" class="buttons">Sequence ar^n; when a-4 r=3</button></p>
    </div>
</form>
</body>
</html>
PHP Functions:
<?php
function Sequence1()
{
    $output = "";
    $num = 0;
    $result = 0;
    for ($i = 0; $i < 9; $i++) {
        $num++;
        $num1 = (2 * $num);
        $result = 10 - $num1;
        $output .= "When n=${num};   10-2n = 10-2x $num1 = 10 - $num1 = $result  <br>";
    }
    return $output;
}
function Sequence2()
{
    $output = "";
    $num = 0;
    $result = 0;
    for ($i = 0; $i < 9; $i++) {
        $num++;
        $num1 = (4 * $num);
        $result = $num1 + 3;
        $output .= "When n=${num};    4n+3 = 4 x $num + 3 = $num1 + 3 = $result <br>";
    }
    return $output;
}
function Sequence3()
{
    $output = "";
    $num = 0;
    $result = 0;
    for ($i = 0; $i < 9; $i++) {
        $num++;
        $num1 = ($num * $num);
        $result = $num1 - 2;
        $output .= "When n=${num};    n*n-2 = $num x $num - 2 = $num1 - 2 = $result <br>";
    }
    return $output;
}
function Sequence4() {
    $output = "";
    $num = 0;
    $result = 0;
    for($i = 0; $i < 9; $i++) {
        $a = 3;
        $r = 2;
        $num++;
        $num1 = $a * pow($r, $num -1);
        $result = $num1 * 2;
        $output .= "When n=${num};    $num1 x 2 = $result <br>";
    }
    return $output;
}
?>
<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>Sequence Tester</title>
    <link rel="stylesheet" type="text/css" href="q2.css">
</head>
<body>
<div class="header">
    <header><h1>Sequence Tester</h1></header>
</div>
<!--Create divs to hold each button click-->
<div class="seq_result">
    <h3>You selected <?php echo $v; ?></h3>
    <p><?php echo $j; ?></p>
</div>
<div class="home">
    <a href="q2_index.html">Back to Homepage</a>
</div>
</body>
</html>