不确定该方法不返回任何值的原因
Not sure why the method is not returning any value
我知道我已经有了类似的帖子，但我一辈子都无法弄清楚这两个片段之间的区别，因为我只能从第一个例子中得到返回值，而不能从第二个例子中获得；示例中的两个方法都返回一个值。
更奇怪（或令人沮丧）的是，PHP解释器在第二个例子中没有抛出任何错误；它只是呈现一个空白屏幕。我正在XAMPP上运行，并且我相信"；显示错误"；，等等被设置为真。
第一个例子（效果很好）：
<html>
<?php
function myMethod() {
return "testing";
}
?>
<script type="text/javascript">
var val= "<?php echo myMethod(); ?>";
document.write(val);
</script>
</html>
第二个示例（请注意，只有"myMethod"函数发生了更改）：
<html>
<?php
function myMethod() {
error_reporting(E_ALL);
echo "<h2>Querying...</h2>'n";
/* Get the port for the WWW service. */
$service_port = getservbyname('www', 'tcp');
/* Get the IP address for the target host. */
$address = gethostbyname('www.example.com');
/* Create a TCP/IP socket. */
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
if ($socket === false) {
echo "socket_create() failed: reason: " . socket_strerror(socket_last_error()) . "'n";
} else {
echo "OK.'n";
}
echo "Attempting to connect to '$address' on port '$service_port'...";
$result = socket_connect($socket, $address, $service_port);
if ($result === false) {
echo "socket_connect() failed.'nReason: ($result) " . socket_strerror(socket_last_error($socket)) . "'n";
} else {
echo "OK.'n";
}
$in = "HEAD / HTTP/1.1'r'n";
$in .= "Host: www.example.com'r'n";
$in .= "Connection: Close'r'n'r'n";
$out = '';
echo "Sending HTTP HEAD request...";
socket_write($socket, $in, strlen($in));
echo "OK.'n";
echo "Reading response:'n'n";
while ($out = socket_read($socket, 2048)) {
echo $out;
return 'test';
}
echo "Closing socket...";
socket_close($socket);
echo "OK.'n'n";
}
?>
<script type="text/javascript">
var val= "<?php echo myMethod(); ?>";
document.write(val);
</script>
</html>
除了系统所说的，看起来变量包含正确的数据，但是"；document.write"；似乎没有正确地将其输出到浏览器视图：
<html>
<script type="text/javascript">
var val= "<h2>Querying...</h2>
OK.
Attempting to connect to '192.0.43.10' on port '80'...OK.
Sending HTTP HEAD request...OK.
Reading response:
HTTP/1.0 302 Found
Location: http://www.iana.org/domains/example/
Server: BigIP
Connection: close
Content-Length: 0
test";
document.write(val);
</script>
</html>
查看浏览器的源代码视图。脚本的工作方式似乎与所期望的一样（见下文）。
但是请注意在JavaScript中，不可能以这种方式构建多行字符串。
在JavaScript中构建多行字符串时，必须执行以下操作：
var str = "first line'n";
str += "second line'n";
或者使用join函数：
var str = [
"first line",
"second line"
].join("'n");
以下是您的输出：
<html>
<script type="text/javascript">
var val= "<h2>Querying...</h2>
OK.
Attempting to connect to '192.0.43.10' on port '80'...OK.
Sending HTTP HEAD request...OK.
Reading response:
HTTP/1.0 302 Found
Location: http://www.iana.org/domains/example/
Server: BigIP
Connection: close
Content-Length: 0
test";
document.write(val);
</script>
</html>
将所有回波更改为本地存储在变量中：
function myMethod()
{
error_reporting(E_ALL);
$temp = "<h2>Querying...</h2>'n";
/* Get the port for the WWW service. */
$service_port = getservbyname('www', 'tcp');
/* Get the IP address for the target host. */
$address = gethostbyname('www.example.com');
/* Create a TCP/IP socket. */
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
if ($socket === false) {
echo "socket_create() failed: reason: " . socket_strerror(socket_last_error()) . "'n";
} else {
echo "OK.'n";
}
$temp .= "Attempting to connect to '$address' on port '$service_port'...";
$result = socket_connect($socket, $address, $service_port);
if ($result === false) {
$temp .= "socket_connect() failed.'nReason: ($result) " . socket_strerror(socket_last_error($socket)) . "'n";
} else {
$temp .= "OK.'n";
}
$in = "HEAD / HTTP/1.1'r'n";
$in .= "Host: www.example.com'r'n";
$in .= "Connection: Close'r'n'r'n";
$out = '';
$temp .= "Sending HTTP HEAD request...";
socket_write($socket, $in, strlen($in));
$temp .="OK.'n";
$temp .="Reading response:'n'n";
while ($out = socket_read($socket, 2048)) {
$temp .= $out;
return 'test';
}
$temp .= "Closing socket...";
socket_close($socket);
$temp .= "OK.'n'n";
return $temp;
}
因为JavaScript无法支持多行文本。您可以使用json_encode将输出作为数组返回。在JavaScript:中将其用作数组
<?php
function myMethod()
{
error_reporting(E_ALL);
$return = array();
$return[] = "<h2>Querying...</h2>'n";
/* Get the port for the WWW service. */
$service_port = getservbyname('www', 'tcp');
/* Get the IP address for the target host. */
$address = gethostbyname('www.example.com');
/* Create a TCP/IP socket. */
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
if ($socket === false) {
$return[] = "socket_create() failed: reason: " . socket_strerror(socket_last_error()) . "'n";
} else {
$return[] = "OK.'n";
}
$return[] = "Attempting to connect to '$address' on port '$service_port'...";
$result = socket_connect($socket, $address, $service_port);
if ($result === false) {
$return[] = "socket_connect() failed.'nReason: ($result) " . socket_strerror(socket_last_error($socket)) . "'n";
} else {
$return[] = "OK.'n";
}
$in = "HEAD / HTTP/1.1'r'n";
$in .= "Host: www.example.com'r'n";
$in .= "Connection: Close'r'n'r'n";
$out = '';
$return[] = "Sending HTTP HEAD request...";
socket_write($socket, $in, strlen($in));
$return[] = "OK.'n";
$return[] = "Reading response:'n'n";
while ($out = socket_read($socket, 2048)) {
$return[] = $out;
}
$return[] = "Closing socket...";
socket_close($socket);
$return[] = "OK.'n'n";
return json_encode($return);
}
?>
<script type="text/javascript">
var val= <?php echo myMethod(); ?>;
for(i in val) {
document.write(val[i] + '<br '/>');
}
</script>
我编辑了您的代码问题。它在HTML和JavaScript代码中，而不是在PHP中。
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Untitled Document</title>
</head>
<body>
<?php
function myMethod()
{
error_reporting(E_ALL);
echo "<h2>Querying...</h2>'n";
/* Get the port for the WWW service. */
$service_port = getservbyname('www', 'tcp');
/* Get the IP address for the target host. */
$address = gethostbyname('www.example.com');
/* Create a TCP/IP socket. */
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
if ($socket === false) {
echo "socket_create() failed: reason: " . socket_strerror(socket_last_error()) . "'n";
} else {
echo "OK.'n";
}
echo "Attempting to connect to '$address' on port '$service_port'...";
$result = socket_connect($socket, $address, $service_port);
if ($result === false) {
echo "socket_connect() failed.'nReason: ($result) " . socket_strerror(socket_last_error($socket)) . "'n";
} else {
echo "OK.'n";
}
$in = "HEAD / HTTP/1.1'r'n";
$in .= "Host: www.example.com'r'n";
$in .= "Connection: Close'r'n'r'n";
$out = '';
echo "Sending HTTP HEAD request...";
socket_write($socket, $in, strlen($in));
echo "OK.'n";
echo "Reading response:'n'n";
while ($out = socket_read($socket, 2048)) {
echo $out;
return 'test';
}
echo "Closing socket...";
socket_close($socket);
echo "OK.'n'n";
}
?>
<?php echo myMethod(); ?>
</body>
</html>
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