open_fileT_open_fileOpenFileOpenFileopen_file (算子)

名称

open_fileT_open_fileOpenFileOpenFileopen_file — 以文本或二进制格式打开文件。

签名

描述

open_fileopen_fileOpenFileOpenFileOpenFileopen_file opens a file in text format or in binary format. The name of the file is defined by the parameter FileNameFileNameFileNameFileNamefileNamefile_name. The operator open_fileopen_fileOpenFileOpenFileOpenFileopen_file returns a handle to the file in the output parameter FileHandleFileHandleFileHandleFileHandlefileHandlefile_handle. The parameter FileTypeFileTypeFileTypeFileTypefileTypefile_type determines the type of the file. For text files this parameter can also be used to specify the encoding used for strings in that file, where besides UTF-8 only the local-8-bit encoding is supported.

The following settings for FileTypeFileTypeFileTypeFileTypefileTypefile_type are supported:

'input'"input""input""input""input""input"：

An already existing input file is opened for reading in text format.

'output'"output""output""output""output""output"：

A new output file is opened for writing in text format.

'append'"append""append""append""append""append"：

An already existing output file is opened for writing at the end of the file in text format.

'input_binary'"input_binary""input_binary""input_binary""input_binary""input_binary"：

An already existing input file is opened for reading in binary format.

'output_binary'"output_binary""output_binary""output_binary""output_binary""output_binary"：

A new output file is opened for writing in binary format.

'append_binary'"append_binary""append_binary""append_binary""append_binary""append_binary"：

An already existing output file is opened for writing at the end of the file in binary format.

For text files the tuple passed to FileTypeFileTypeFileTypeFileTypefileTypefile_type can be extended by one of the following encoding settings:

'utf8_encoding'"utf8_encoding""utf8_encoding""utf8_encoding""utf8_encoding""utf8_encoding"：

Strings in the file are encoded in UTF-8. This is the default, so for UTF-8 encoded files and all files which use only pure 7-bit US-ASCII characters this value can be omitted.

'locale_encoding'"locale_encoding""locale_encoding""locale_encoding""locale_encoding""locale_encoding"：

Strings in the file are encoded in the local-8-bit encoding which depends on the system's current locale setting. Valid encodings are defined, e.g., under Windows by the code pages 1252 (a Microsoft dialect of Latin-1) or 932 (Shift-JIS) or on Linux by the locales en_US.utf8, de_DE.iso885915, or ja_JP.sjis.

'ignore_encoding'"ignore_encoding""ignore_encoding""ignore_encoding""ignore_encoding""ignore_encoding"：

The encoding of the strings that are read from the file or written into it is not handled. In that mode multi-byte characters are neither processed nor interpreted, the operator fread_charfread_charFreadCharFreadCharFreadCharfread_char returns always one byte, and separator characters that depend on a specific locale are not handled in fread_linefread_lineFreadLineFreadLineFreadLinefread_line and fread_stringfread_stringFreadStringFreadStringFreadStringfread_string。Furthermore, the strings are not transcoded into or from the current encoding of the HALCON library.

Note: Strings are still transcoded in the HALCON C/C++ interface, when the encoding of the HALCON C/C++ interface differs from the encoding of the HALCON library. For HDevelop scripts, the encoding is always set to UTF-8. To avoid transcoding of strings to HDevelop, the encoding of the HALCON library should be set to UTF-8.

For the standard terminal input and output streams, the file names 'standard'"standard""standard""standard""standard""standard" ('input'"input""input""input""input""input" and 'output'"output""output""output""output""output") and 'error'"error""error""error""error""error" (only 'output'"output""output""output""output""output") are reserved.

执行信息

• 多线程类型：可重入（与非独占算子并行运行）。
• 多线程作用域：全局（可从任何线程调用）。
• 未采用并行化处理。

此算子返回一个句柄。请注意，即使该句柄被用作特定算子的输入参数，这些算子仍可能改变此句柄类型的实例状态。

参数

示例（HDevelop）

* Creating an output text file with the name '/tmp/log.txt' and writing
* of a string:
   open_file('/tmp/log.txt','output',FileHandle)
   fwrite_string(FileHandle,'these are the first and last lines')
   fnew_line(FileHandle)
   close_file(FileHandle)
   

结果

如果参数有效，算子 open_fileopen_fileOpenFileOpenFileOpenFileopen_file 返回值 2 ( H_MSG_TRUE )。如有必要，则抛出异常。

可能的后继

fwrite_stringfwrite_stringFwriteStringFwriteStringFwriteStringfwrite_string, fread_charfread_charFreadCharFreadCharFreadCharfread_char, fread_stringfread_stringFreadStringFreadStringFreadStringfread_string, fread_linefread_lineFreadLineFreadLineFreadLinefread_line, fread_serialized_itemfread_serialized_itemFreadSerializedItemFreadSerializedItemFreadSerializedItemfread_serialized_item, fwrite_serialized_itemfwrite_serialized_itemFwriteSerializedItemFwriteSerializedItemFwriteSerializedItemfwrite_serialized_item, fread_bytesfread_bytesFreadBytesFreadBytesFreadBytesfread_bytes, fwrite_bytesfwrite_bytesFwriteBytesFwriteBytesFwriteBytesfwrite_bytes, close_fileclose_fileCloseFileCloseFileCloseFileclose_file

另见

close_fileclose_fileCloseFileCloseFileCloseFileclose_file

模块

基础