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December 17, 2007

SetCompressionLevel w/ Self-Extracting EXE

The SetCompressionLevel method appears to have no effect. Changing it from 0 to 9 has no effect on the speed of the zipping or the size of the resulting file (which is a self-extracting executable).

Yes, that is correct. When Chilkat Zip creates a self-extracting executable via the WriteEXE method, the result is not simply a .exe with an embedded .zip archive. The .exe instead contains an archive in a format known (internal to Chilkat) as the Chilkat Simple Archive Format. The main features of the format are that:

1) Filenames are stored in utf-8, to support all languages.
2) There are no size limits on either individual files or the size of the entire archive.
3) The choice of compression internally is self-adaptive. Content that doesn’t compress, such as GIF, JPG, PDF, etc. is stored as-is, while other content may be compressed with settings appropriate to achieve maximum compression.

The Chilkat Simple Archive Format will eventually become publicly documented and exposed as the foundation to a Chilkat Backup component.

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