The opendir() function opens a directory handle to be used by the closedir(), readdir(), and rewinddir() functions.
opendir()函数的作用是：打开目录句柄。
This function returns a directory stream on success and FALSE and an error on failure. You can hide the error output by adding an '@' in front of the function name.
如果该函数成功运行，将返回一组目录流（一组目录字符串），如果失败将返回错误[error]。你可以在函数的最前面加上“@”来隐藏错误。
Syntax
语法
opendir(directory,context)
Parameter
参数 Description
描述
directory Required. Specifies the directory to stream
必要参数。指定目录对象
context Optional. Specifies the context of the directory handle. Context is a set of options that can modify the behavior of a stream
可选参数。指定需要处理的目录对象的context。这个context包括了一组选项，它可以对文本流的显示方式进行改变
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Tips and Notes
注意点
Note: From PHP 5 the directory parameter supports the ftp:// URL wrapper.
注意：PHP 5.0以上版本中，目录参数支持ftp://URL。
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Example 1
案例1
<?php
//Open images directory
$dir = opendir("images");//List files in images directory
while (($file = readdir($dir)) !== false)
{
echo "filename: " . $file . "
";
}
closedir($dir);
?>
The output of the code above could be:
上述代码将输出下面的结果：
filename: .
filename: ..
filename: cat.gif
filename: dog.gif
filename: food
filename: horse.gif
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Example 2
案例2
This example hides the error if opendir() fails:
这个例子展示了：如果dir()函数运行失败，自动将错误信息隐藏。具体如下：
<?php
//Open images directory
$dir = @ opendir("images");//List files in images directory
while (($file = readdir($dir)) !== false)
{
echo "filename: " . $file . "
";
}
closedir($dir);
?>
The output of the code above could be:
上述代码将输出下面的结果：
filename: .
filename: ..
filename: cat.gif
filename: dog.gif
filename: food
filename: horse.gif