PHP xmlwriter_start_pi()用法及代碼示例

定義和用法

XML 是一種 mark-up 語言，用於在網絡上共享數據，XML 用於人類 read-able 和機器 read-able。 XMLWriter 擴展內部具有 libxml xmlWriter API，用於編寫/創建 XML 文檔的內容。由此生成的 XML 文檔是非緩存的和 forward-only。

這個xmlwriter_start_pi()函數接受一個 XMLWriter 類的對象和一個表示處理指令目標的字符串作為參數，並創建一個起始 PI 標記。

用法

xmlwriter_start_pi($writer, $str);

參數

Sr.No	參數及說明
1	writer(Mandatory) 這是 XMLWriter 類的一個對象，表示您要修改/創建的 XML 文檔。
2	str(Mandatory) 這是一個字符串值，表示處理指令的目標。

返回值

此函數返回一個布爾值，成功時為 TRUE，失敗時為 FALSE。

PHP版本

這個函數最初是在 PHP 版本 5 中引入的，並且適用於所有後續版本。

示例

下麵的例子演示了xmlwriter_start_pi()函數 -

<?php
   //Opening a writer
   $uri = "result.xml";
   $writer = xmlwriter_open_uri($uri);

   //Setting the indentation on
   xmlwriter_set_indent($writer, TRUE);

   //Starting the document
   xmlwriter_start_document($writer);
   xmlwriter_set_indent_string($writer, "  ");

   //Starting the processing instruction
   xmlwriter_start_pi($writer, 'php');   
   
   //Write the instruction content of the processing instruction
   xmlwriter_text($writer, 'echo $a;');   
   
   //Ending the processing instruction
   xmlwriter_end_pi($writer); 

   //Setting the indentation
   xmlwriter_set_indent_string($writer, "    ");

   //Starting an element
   xmlwriter_start_element($writer, 'Tutorial');
   xmlwriter_start_element($writer, 'name');
   
   //Adding text to the element
   xmlwriter_text($writer, 'JavaFX');  
   xmlwriter_end_element($writer);
   xmlwriter_start_element($writer, 'Author');
   
   //Adding text to the element
   xmlwriter_text($writer, 'Krishna');  
   xmlwriter_end_element($writer);

   //Ending the element
   xmlwriter_end_element($writer);
   
   //Ending the document
   xmlwriter_end_document($writer);
?>

這將生成以下 XML 文檔 -

<?xml version="1.0"?>
<?php echo $a;?>
<Tutorial>
   <name>JavaFX</name>
   <Author>Krishna</Author>
</Tutorial>

示例

以下是麵向對象風格的此函數的示例 -

<?php
   //Creating an XMLWriter
   $writer = new XMLWriter();

   //Opening a writer
   $uri = "result.xml";
   $writer->openUri($uri);

   //Setting the indentation on
   $writer->setIndent(TRUE);

   //Starting the document
   $writer->startDocument();
   $writer->setIndentString("  ");

   //Starting the processing instruction
   $writer->startPi('php');   
   
   //Write the instruction content of the processing instruction
   $writer->text('echo $a;');   
   
   //Ending the processing instruction
   $writer->endPi(); 

   //Setting the indentation
   $writer->setIndentString("    ");

   //Starting an element
   $writer->startElement('Tutorial');
   $writer->startElement('name');
   
   //Adding text to the element
   $writer->text('JavaFX');  
   $writer->endElement();
   $writer->startElement('Author');
   
   //Adding text to the element
   $writer->text('Krishna');  
   $writer->endElement();

   //Ending the element
   $writer->endElement();
   
   //Ending the document
   $writer->endDocument();
?>

這將生成以下 XML 文檔 -

<?xml version="1.0"?>
<?php echo $a;?>
<Tutorial>
   <name>JavaFX</name>
   <Author>Krishna</Author>
</Tutorial>