Retrieve the default stream context

# stream_context_get_default

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

stream_context_get_default — Retrieve the default stream context

### 说明

function stream_context_get_default(?array `$options` = `null`): resource

Returns the default stream context which is used whenever file operations (fopen(), file_get_contents(), etc...) are called without a context parameter. Options for the default context can optionally be specified with this function using the same syntax as stream_context_create().

### 参数

`options`
  `options` must be an associative array of associative arrays in the format `$arr['wrapper']['option'] = $value`, or `null`.

### 返回值

A stream context resource.

### 更新日志

版本 | 说明
--- | ---
8.0.0 | `options` is now nullable.

### 示例

示例 #1 Using stream_context_get_default()

    <?php
    $default_opts = [
      'http' => [
        'method' => "GET",
        'header' => "Accept-language: en\r\n" .
                    "Cookie: foo=bar",
        'proxy' =>  "tcp://10.54.1.39:8000",
      ]
    ];

    $alternate_opts = [
      'http' => [
        'method'  => "POST",
        'header'  => "Content-type: application/x-www-form-urlencoded\r\n" .
                     "Content-length: " . strlen("baz=bomb"),
        'content' => "baz=bomb",
      ]
    ];

    $default = stream_context_get_default($default_opts);
    $alternate = stream_context_create($alternate_opts);

    /* Sends a regular GET request to proxy server at 10.54.1.39
     * For www.example.com using context options specified in $default_opts
     */
    readfile('http://www.example.com');

    /* Sends a POST request directly to www.example.com
     * Using context options specified in $alternate_opts
     */
    readfile('http://www.example.com', false, $alternate);

    ?>

### 参见

- stream_context_create() - 创建资源流上下文
- stream_context_set_default() - Set the default stream context
- Listing of supported wrappers with context options (支持的协议和封装协议).

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