blocks|key|450307|text|大多数表单输入总是被设置的，即使没有填满，所以你也必须检查是否为空。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|450308|由于!empty()已经对这两种情况都进行了检查，因此可以使用以下命令：|offset|length|style|CODE|450309|if+(!empty($_POST["mail"]))+{
++++echo+"Yes,+mail+is+set";++++
}+else+{++
++++echo+"No,+mail+is+not+set";
}|code-block|syntax|javascript|450310|entityMap^0|0|2|8|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@$D|Q|E|R|F|G]]|9|@]|A|$]]|$1|H|3|I|5|J|7|S|8|@]|9|@]|A|$K|L]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

<p>Most form inputs are always set, even if not filled up, so you must check for the emptiness too.</p>

<p>Since <code>!empty()</code> is already checks for both, you can use this:</p>

<pre><code>if (!empty($_POST["mail"])) {
    echo "Yes, mail is set";    
} else {  
    echo "No, mail is not set";
}
</code></pre>


blocks|key|232306|text|使用!empty而不是isset。对于$_POST，isset返回true，因为$_POST数组是超全局数组，且始终存在(set)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|232307|或者更好地使用$_SERVER['REQUEST_METHOD']+==+'POST'|232308|entityMap^0|2|6|B|5|J|6|14|6|0|7|10|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]|$9|M|A|N|B|C]|$9|O|A|P|B|C]|$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|V|8|@]|D|@]|E|$]]]|I|$]]

<p>Use <code>!empty</code> instead of <code>isset</code>.
isset return true for <code>$_POST</code> because <code>$_POST</code> array is superglobal and always exists (set).</p>

<p>Or better use <code>$_SERVER['REQUEST_METHOD'] == 'POST'</code></p>


blocks|key|450290|text|如果发送的表单为空，则仍将发送$_POST['mail']，但值为空。要检查该字段是否为空，您需要检查|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|450291|if(isset($_POST["mail"])+&&+trim($_POST["mail"])+!=+"")+{+..+}|code-block|syntax|javascript|450292|entityMap^0|F|E|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

<p>If you send the form empty, <code>$_POST['mail']</code> will still be sent, but the value is empty. To check if the field is empty you need to check</p>
<pre><code>if(isset($_POST[&quot;mail&quot;]) &amp;&amp; trim($_POST[&quot;mail&quot;]) != &quot;&quot;) { .. }
</code></pre>


blocks|key|232491|text|您可以简单地使用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|232492|if($_POST['username']+and+$_POST['password']){
++$username+=+$_POST['username'];
++$password+=+$_POST['password'];
}|code-block|syntax|javascript|232493|或者，使用empty()|offset|length|232494|if(!empty($_POST['username'])+and+!empty($_POST['password'])){
++$username+=+$_POST['username'];
++$password+=+$_POST['password'];
}|232495|entityMap|0|LINK|mutability|MUTABLE|url|http://php.net/manual/en/function.empty.php^0|0|0|5|7|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@$I|X|J|Y|1|Z]]|A|$]]|$1|K|3|L|5|D|7|10|8|@]|9|@]|A|$E|F]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|T]]]]

<p>You can simply use:</p>

<pre><code>if($_POST['username'] and $_POST['password']){
  $username = $_POST['username'];
  $password = $_POST['password'];
}
</code></pre>

<p>Alternatively, use <a href="http://php.net/manual/en/function.empty.php" rel="nofollow">empty()</a></p>

<pre><code>if(!empty($_POST['username']) and !empty($_POST['password'])){
  $username = $_POST['username'];
  $password = $_POST['password'];
}
</code></pre>


blocks|key|450350|text|将以下属性添加到输入文本表单：required="required"。如果表单未填写，则不允许用户提交表单。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|450351|您的新代码将是：|450352|<form+name="new+user"+method="post"+action="step2_check.php">+
<input+type="text"+name="mail"+required="required"/>+<br+/>
<input+type="password"+name="password"+required="required"/><br+/>
<input+type="submit"++value="continue"/>|code-block|syntax|javascript|450353|if+(isset($_POST["mail"]))+{
++++echo+"Yes,+mail+is+set";++++
}|450354|entityMap^0|F|J|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|T|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|U|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|J|7|V|8|@]|D|@]|E|$K|L]]|$1|O|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|P|$]]

<p>Add the following attribute to the input text form: <code>required="required"</code>.
If the form is not filled, it will not allow the user to submit the form.</p>

<p>Your new code will be:</p>

<pre class="lang-html prettyprint-override"><code>&lt;form name="new user" method="post" action="step2_check.php"&gt; 
&lt;input type="text" name="mail" required="required"/&gt; &lt;br /&gt;
&lt;input type="password" name="password" required="required"/&gt;&lt;br /&gt;
&lt;input type="submit"  value="continue"/&gt;
</code></pre>

<pre class="lang-php prettyprint-override"><code>if (isset($_POST["mail"])) {
    echo "Yes, mail is set";    
}
</code></pre>


blocks|key|450499|text|<?php
++++if(isset($_POST['mail'])+&&+$_POST['mail']!='')+{
++++++++echo+"Yes,+mail+is+set";
++++}else{
++++++++echo+"N0,+mail+is+not+set";
++++}
?>|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|450500|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>&lt;?php
    if(isset($_POST['mail']) &amp;&amp; $_POST['mail']!='') {
        echo "Yes, mail is set";
    }else{
        echo "N0, mail is not set";
    }
?&gt;
</code></pre>


blocks|key|450531|text|先检查表单是否已提交，然后再检查字段。您还应该清理该字段以防止黑客攻击。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|450532|form+name="new+user"+method="post"+action="step2_check.php">+
++++<input+type="text"+name="mail"/>+<br+/>
++++<input+type="password"+name="password"/><br+/>
++++<input+type="submit"++id="SubmitForm"+name=+"SubmitForm"+value="continue"/>
</form>|code-block|syntax|javascript|450533|step2_check：|450534|if+(isset($_POST["SubmitForm"]))
+++{
+++$Email+=++sanitize_text_field(stripslashes($_POST["SubmitForm"]));
+++if(!empty($Email))
+++++echo+"Yes,+mail+is+set";+
+++else
+++++echo+"N0,+mail+is+not+set";
+++}+
}|450535|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

<p>Check to see if the FORM has been submitted first, then the field.  You should also sanitize the field to prevent hackers.</p>

<pre><code>form name="new user" method="post" action="step2_check.php"&gt; 
    &lt;input type="text" name="mail"/&gt; &lt;br /&gt;
    &lt;input type="password" name="password"/&gt;&lt;br /&gt;
    &lt;input type="submit"  id="SubmitForm" name= "SubmitForm" value="continue"/&gt;
&lt;/form&gt;
</code></pre>

<p>step2_check:</p>

<pre><code>
if (isset($_POST["SubmitForm"]))
   {
   $Email =  sanitize_text_field(stripslashes($_POST["SubmitForm"]));
   if(!empty($Email))
     echo "Yes, mail is set"; 
   else
     echo "N0, mail is not set";
   } 
}

</code></pre>


blocks|key|232467|text|要回答张贴的问题:+isset和empty一起给出了三个条件。这也可以由Javascript通过ajax命令使用。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|232468|$errMess="Didn't+test";+++//+This+message+should+not+show
if(isset($_POST["foo"])){+//+does+it+exist+or+not
++++$foo+=+$_POST["foo"];+//+save+$foo+from+POST+made+by+HTTP+request
++++if(empty($foo)){++++++//+exist+but+it's+null
++++++++$errMess="Empty";+//+#1+Nothing+in+$foo+it's+emtpy

++++}+else+{++++++++++++++//+exist+and+has+data
++++++++$errMess="None";++//+#2+Something+in+$foo+use+it+now
++++++}
}+else+{++++++++++++++++++//+couldn't+find+?foo=dataHere
+++++$errMess="Missing";++//+#3+There's+no+foo+in+request+data
++}

echo+"Was+there+a+problem:+".$errMess."!";|code-block|syntax|javascript|232469|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

<p>To answer the posted question: isset and empty together gives three conditions. This can be used by Javascript with an ajax command as well.</p>

<pre><code>$errMess="Didn't test";   // This message should not show
if(isset($_POST["foo"])){ // does it exist or not
    $foo = $_POST["foo"]; // save $foo from POST made by HTTP request
    if(empty($foo)){      // exist but it's null
        $errMess="Empty"; // #1 Nothing in $foo it's emtpy

    } else {              // exist and has data
        $errMess="None";  // #2 Something in $foo use it now
      }
} else {                  // couldn't find ?foo=dataHere
     $errMess="Missing";  // #3 There's no foo in request data
  }

echo "Was there a problem: ".$errMess."!";
</code></pre>


blocks|key|232497|text|您可以尝试这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|232498|if+(isset($_POST["mail"])+!==+false)+{
++++echo+"Yes,+mail+is+set";++++
}else{++
++++echo+"N0,+mail+is+not+set";
}|code-block|syntax|javascript|232499|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

<p>You can try this:</p>

<pre><code>if (isset($_POST["mail"]) !== false) {
    echo "Yes, mail is set";    
}else{  
    echo "N0, mail is not set";
}
</code></pre>


blocks|key|450461|text|<form+name="new+user"+method="post"+action="step2_check.php">+
++<input+type="text"+name="mail"+required="required"/>+<br+/>
++<input+type="password"+name="password"+required="required"/><br+/>
++<input+type="submit"++value="continue"/>
</form>

<?php
if+(!empty($_POST["mail"]))+{
++++echo+"Yes,+mail+is+set";++++
}else{++
++++echo+"N0,+mail+is+not+set";
}
?>|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|450462|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>&lt;form name="new user" method="post" action="step2_check.php"&gt; 
  &lt;input type="text" name="mail" required="required"/&gt; &lt;br /&gt;
  &lt;input type="password" name="password" required="required"/&gt;&lt;br /&gt;
  &lt;input type="submit"  value="continue"/&gt;
&lt;/form&gt;

&lt;?php
if (!empty($_POST["mail"])) {
    echo "Yes, mail is set";    
}else{  
    echo "N0, mail is not set";
}
?&gt;
</code></pre>


blocks|key|450489|text|你可以试一试|type|unstyled|depth|inlineStyleRanges|entityRanges|data|450490|+<?php

+++++if+(isset($_POST["mail"]))+{
++++++++++++echo+"Yes,+mail+is+set";++++
++++++++}else{++
++++++++++++echo+"N0,+mail+is+not+set";
++++++++}
++?>|code-block|syntax|javascript|450491|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

<p>You can try,</p>

<pre><code> &lt;?php

     if (isset($_POST["mail"])) {
            echo "Yes, mail is set";    
        }else{  
            echo "N0, mail is not set";
        }
  ?&gt;
</code></pre>


blocks|key|450608|text|$-POST方法:如果我们在表单标记中使用POST方法来传递数据，我们可以使用$_POST+array.using在服务器中查找数据。($_+POST‘name’)使用POST方法从表单发送的信息对其他人是不可见的(所有名称/值都嵌入在HTTP请求的主体中)，并且对要发送的信息量没有限制。示例代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|450609|<html>
<head>
</head>
<body>
<?php
if(isset($_POST['submit']))
{if(isset($_POST['name'])+&&+isset($_POST['roll']))
{echo"<h1>form+submitted</h1>";echo"your+name+is".+$_POST['name']."<br>";
echo+"your+roll+number+is".+$_POST['roll']."<br>";}}
else{?>
<form+action=""+method="POST">
Name:<input+type="text"+name="name"><br><br>
Roll:<input+type="text"+name="roll"><br>
<br><input+type="submit"+value="submit"+name="submit">
</form>
<?php}?>
</body>
</html>|code-block|syntax|javascript|450610|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

<p>$-POST METHOD:
if we use POST method in the form tag to pass data,we can find data in the server using $_POST array.using this array name we fetch data from server.($_POST['name'])Information sent from a form with the POST method is invisible to others(all names/values are embedded within the body of the HTTP request) and has no limits n the amount of information to send.
Example Code:</p>
<pre><code>&lt;html&gt;
&lt;head&gt;
&lt;/head&gt;
&lt;body&gt;
&lt;?php
if(isset($_POST['submit']))
{if(isset($_POST['name']) &amp;&amp; isset($_POST['roll']))
{echo&quot;&lt;h1&gt;form submitted&lt;/h1&gt;&quot;;echo&quot;your name is&quot;. $_POST['name'].&quot;&lt;br&gt;&quot;;
echo &quot;your roll number is&quot;. $_POST['roll'].&quot;&lt;br&gt;&quot;;}}
else{?&gt;
&lt;form action=&quot;&quot; method=&quot;POST&quot;&gt;
Name:&lt;input type=&quot;text&quot; name=&quot;name&quot;&gt;&lt;br&gt;&lt;br&gt;
Roll:&lt;input type=&quot;text&quot; name=&quot;roll&quot;&gt;&lt;br&gt;
&lt;br&gt;&lt;input type=&quot;submit&quot; value=&quot;submit&quot; name=&quot;submit&quot;&gt;
&lt;/form&gt;
&lt;?php}?&gt;
&lt;/body&gt;
&lt;/html&gt;
</code></pre>


<p>I have a form on one page that submits to another page. There, it checks if the input <code>mail</code> is filled. If so then do something and if it is not filled, do something else. I don't understand why it always says that it is set, even if I send an empty form. What is missing or wrong?</p>
<p><code>step2.php</code>:</p>
<pre><code>&lt;form name=&quot;new user&quot; method=&quot;post&quot; action=&quot;step2_check.php&quot;&gt; 
    &lt;input type=&quot;text&quot; name=&quot;mail&quot;/&gt; &lt;br /&gt;
    &lt;input type=&quot;password&quot; name=&quot;password&quot;/&gt;&lt;br /&gt;
    &lt;input type=&quot;submit&quot;  value=&quot;continue&quot;/&gt;
&lt;/form&gt;
</code></pre>
<p><code>step2_check.php</code>:</p>
<pre><code>if (isset($_POST[&quot;mail&quot;])) {
    echo &quot;Yes, mail is set&quot;;    
} else {    
    echo &quot;N0, mail is not set&quot;;
}
</code></pre>


If isset $_POST

服务器

我在一个页面上有一个表单，该表单提交到另一个页面。在那里，它检查输入mail是否已填充。如果是这样，那么做一些事情，如果它没有填满，做一些其他的事情。我不明白为什么它总是说设置好了，即使我发送了一个空的表单。丢失或错误的是什么？step2.php<form name="new user" method="post" action="step2_check.php">     <input type

问If isset $_POST
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