DataFlex

Compressing and Decompressing Files Using Streaming (CompressFile / DecompressFile)

See more Compression Examples

This example demonstrates how to compress a file to a binary format and then restore it using the Chilkat.Compression class. The CompressFile method reads the source file, compresses it using the specified algorithm, and writes the result to a destination file. The DecompressFile method performs the reverse operation, restoring the original file from the compressed data.

Both operations are performed internally in streaming mode, allowing files of any size to be processed efficiently without loading the entire file into memory. The example also includes a simple verification step by comparing file sizes to confirm that the decompressed output matches the original input.

DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoCompress
    String sInputFile
    String sCompressedFile
    String sDecompressedFile
    Handle hoFac
    Integer iOriginalSize
    Integer iRestoredSize
    String sTemp1

    Move False To iSuccess

    // This example assumes the Chilkat API has already been unlocked.
    // See Global Unlock Sample for sample code.

    Get Create (RefClass(cComChilkatCompression)) To hoCompress
    If (Not(IsComObjectCreated(hoCompress))) Begin
        Send CreateComObject of hoCompress
    End

    // Use the zlib algorithm (recommended for general use)
    Set ComAlgorithm Of hoCompress To "zlib"

    // ------------------------------------------------------------------
    // Compress a file
    // ------------------------------------------------------------------

    Move "c:/temp/example.txt" To sInputFile
    Move "c:/temp/example.txt.zlib" To sCompressedFile

    Get ComCompressFile Of hoCompress sInputFile sCompressedFile To iSuccess
    If (iSuccess = False) Begin
        Showln "Compression failed:"
        Get ComLastErrorText Of hoCompress To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "File compressed successfully:"
    Showln "  Input:      " sInputFile
    Showln "  Compressed: " sCompressedFile

    // ------------------------------------------------------------------
    // Decompress the file back to its original form
    // ------------------------------------------------------------------

    Move "c:/temp/example_restored.txt" To sDecompressedFile

    Get ComDecompressFile Of hoCompress sCompressedFile sDecompressedFile To iSuccess
    If (iSuccess = False) Begin
        Showln "Decompression failed:"
        Get ComLastErrorText Of hoCompress To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "File decompressed successfully:"
    Showln "  Output: " sDecompressedFile

    // ------------------------------------------------------------------
    // Optional: Verify file sizes (basic sanity check)
    // ------------------------------------------------------------------

    Get Create (RefClass(cComCkFileAccess)) To hoFac
    If (Not(IsComObjectCreated(hoFac))) Begin
        Send CreateComObject of hoFac
    End

    Get ComFileSize Of hoFac sInputFile To iOriginalSize
    Get ComFileSize Of hoFac sDecompressedFile To iRestoredSize

    Showln "Original file size:   " iOriginalSize
    Showln "Restored file size:   " iRestoredSize

    If (iOriginalSize = iRestoredSize) Begin
        Showln "Sizes match (basic verification successful)."
    End
    Else Begin
        Showln "Warning: File sizes differ."
    End



End_Procedure