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Expands the contents of a previously specified file.
Syntax
object.ExpandFile( InputFile,
OutputFile, [CompressionType] )
Parameters
- InputFile
- A string value that specifies the name of the file to be expanded. The file must
exist, and it must be a file that was created by a previous call to
the CompressFile method. An error will be returned if the
file cannot be accessed, if it specifies a character device such as
the console, or the if the data is not in a recognizable
format.
- OutputFile
- A string value that specifies the name of the file that will contain the expanded data.
If the file exists, it must be a regular file that can be opened
for writing by the current process and will be overwritten. If the
file does not exist, it will be created. An error will be returned
if a character device, such as the console, is specified as the
file name.
- CompressionType
- A numeric value which determines the algorithm that was used to
compress the data. One of the following values may be specified. If
this argument is not specified, the Deflate algorithm is used. If
the compression type specified by this argument does not match the
actual compression algorithm used to compress the file, an error
will be returned.
| Value |
Constant |
Description |
| 1 |
fileCompressionDeflate |
A compression algorithm that combines LZ77 algorithm for
creating common substrings and Huffman coding to process the
different frequencies of byte sequences in the data stream.
Deflate is widely used by compression software. |
| 2 |
fileCompressionBurrowsWheeler |
A compression algorithm that rearranges blocks of data in
sorted order and then uses Huffman coding to process
different frequencies of data within the block.
Burrows-Wheeler compression provides a better compression
ratio than the Deflate algorithm, however it requires more
resources to perform the compression. |
Return Value
This method returns a value of zero if the file was successfully
decompressed. A non-zero return value specifies an error code which
indicates the reason for the failure.
Remarks
The ExpandFile method expands the contents of a previously
compressed file. Note that this method can only expand files that were compressed
using the control. It cannot expand the contents of a file stored in
an archive format such as PKZip or WinZip.
See Also
CompressFile Method,
DecodeFile Method,
EncodeFile Method
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