如何應用fopen()函數的選擇模式？

如何應用fopen()函數的選擇模式？

一、fopen()函數

在php中使用fopen()函數開啟一個文件，具體語法格式如下：

resource fopen ( string filename , string $mode [, int use_include_path[, resource zcontext ]] )

參數filename 指定開啟的檔案名稱。

注意：

參數filename可以使包含檔案路徑的檔案名稱（例如：「C:/Windows/php.ini」或「./php.ini」），可為了避免不同系統之間切換可能會帶來的麻煩，採用“/”作為路徑分隔符，參數filename 也可以是由魔種協議給出的URL （例如：“http：//mrbccd.cn”或者“ftp：//www.mrbccd.cn//”），如果指定URL 位址，則可以開啟遠端檔案。

參數 mode 設定開啟檔案的方法，參數值如下表：

The parameter use_include_path can be a selection parameter to determine whether to search for filename files in the directory defined by include_path (include_path option of php.ini). For example: set the value of the include_path option in the php.ini file to "E:\AppServ\ www\MR\Instance\07\", if you want the server to open the specified file in this path, set the value of the parameter use_include_path to 1 or TRUE.

Parameter context is called context, which is also an optional parameter. It is a specific option that sets the flow operation and is used to control the operation characteristics of the flow. Generally, only the default stream operation settings are required and there is no need to use this parameter.

2. Mode selection

Different operating systems have different line ending habits when inserting a new line in a text file The choice of line terminator must be suitable for the user's operating system. If the wrong line terminator is used, the output may be a bunch of garbled characters when the file is opened, so it is very important to use the line terminator correctly.

UNIX-based systems use \n as the line terminator, Windows-based systems use \r\n as the line terminator, and Macintosh-based systems use \r as the line terminator.

Under Windows, provide a text conversion flag ("t") to convert \n to \r\n; or you can use ("b") to set the binary mode so that the data will not be modified. Convert. Therefore, there are two options for using line terminators in Windows systems: one is to use the text conversion flag ("t") for conversion; the other is to use ("b") to set the mode parameter mode to binary.

The default conversion mode depends on SAPI and the PHP version used, so in order to facilitate porting, it is recommended to set the appropriate mode when applying the fopen() function.

If you want plain text files with \n as the line terminator to be valid in other applications (such as Notepad). Then it is recommended to use ("t") mode in the script. Use ("b") in other cases.

If you do not specify ("b") mode when operating a binary file, some strange content may be output. Therefore, considering the portability of the program, it is strongly recommended to open the file with fopen() Always use ("b") mode; also, it is recommended to rewrite code that depends on ("t") mode. Make it use the correct line terminators and the correct ("b") pattern.

We will introduce the selection mode of how to apply the fopen() function here. Friends can try it locally~

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