UU Encoding is an algorithm for converting binary data to 6-bit ASCII. This is often needed to send binary files through internet mail gateways. UU Encoding is also commonly used in internet newsgroups for posting binary data. UU Encoding breaks a group of 3 eight bit characters (24-bits) into 4 six bit characters (also 24-bits) and then adds 32 (a space) to each six bit character. This maps it into a transmittable character set.
These characters are: !"#$%&'()*+,-./ 0123456789:;=? @ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_
|(Declarations)||Declarations||Declarations and private variables for the CUUEncode class.|
|InputFileName||Property||Get the name of the input file.|
|OutputFileName||Property||Get the name of the output file.|
|Decode||Method||Decode a file encoded with UUEncoding.|
|Encode||Method||Encode a file using UU Encoding.|
|dblToLong||Private||Perform an unsigned conversion from a Double value to a Long value. This function correctly handles doubles greater than 2,147,483,647 and less than or equal to 4,294,967,295.|
|DecodeByte||Private||Decode a single byte.|
|EncodeByte||Private||Encode a byte by manipulating the byte to ensure that it is a printable character code.|
|GetFileName||Private||Get the name and extension of a fully qualified file name.|
|GetFilePath||Private||Get the path part of a string.|
|IntToByte||Private||Perform an unsigned conversion from an integer value to a byte value. This procedure correctly handles any integer value.
For example, lngNumber = -1 assigns -1 to the variable lngNumber. However, lngNumber = IntToLong(-1) assigns 65,535 to lngNumber.
|IntToLong||Private||Convert an integer value to a long value, treating the integer as unsigned.|
|LongToInt||Private||Perform an unsigned conversion from a long integer value to an integer value.|
|MakeInt||Private||Combine two bytes into an integer.|
|MakeLong||Private||Combine two words (integers) into a long integer. This routine correctly handles negative input values.|
|MakePrintable||Private||Take three bytes and convert them into 4 printable characters.|
|ReadFile||Private||Read the specified number of bytes from the file. Using this function significantly increases the speed of processing files. The alternative to using a file buffer is reading a byte at a time from the file.|
|Shlb||Private||Shift a byte value left by the specified number of bits. Left shifting is a multiplication operation. For the number of bits to shift to the left, raise two to that power, then multiply the result by the original value.|
|Shrb||Private||Shift a byte value right the selected number of places. Right shifting is a division operation. For the number of bits to shift to the right, raise two to that power, then divide the original value by the result.|
|UnMakePrintable||Private||Take 4 printable characters and convert them into 3 bytes.|
' Example of CUUEncode to encode and decode files using UU Encoding. ' ' To try this example, do the following: ' 1. Create a new form ' 2. Create a command button named 'cmdTest' ' 3. Create a text box named txtProgress ' 4. Paste all the code from this example to the new form's module. ' 5. Run the form ' This example assumes that the sample files are located in the folder named by the following constant. Private Const mcstrSamplePath As String = "C:\TVSBSamp" ' By defining the class WithEvents, you can capture the Progress event to display information to your user. ' To use events, this module must be a class or form/report. If you don't want to capture the Progress event, you can use a regular module. Private WithEvents mclsUUEncode As CUUEncode Private Sub cmdTest_Click() ' Comments: Examples of encoding and decoding files using UU Encoding. ' UU Encoding is an algorithm for converting binary data to 6-bit ASCII. ' This is often needed to send binary files through internet mail gateways. ' UU Encoding is also commonly used in internet newsgroups for posting binary data. ' UU Encoding breaks a group of 3 eight bit characters (24 bits) into 4 six bit characters (also 24 bits) and ' then adds 32 (a space) to each six bit character. This maps it into a transmittable character set. Const cstrOriginal As String = mcstrSamplePath & "\original.bmp" Const cstrEncode As String = mcstrSamplePath & "\encode.UUE" Const cstrDecode As String = mcstrSamplePath & "\decode.bmp" ' Initialize class Set mclsUUEncode = New CUUEncode With mclsUUEncode ' Example of creating a UUEncode file from a file .InputFileName = cstrOriginal .OutputFileName = cstrEncode .Encode MsgBox "Compressed file created: " & cstrEncode ' Decoding a UU encoded file .InputFileName = cstrEncode .OutputFileName = cstrDecode .Decode MsgBox "New file created: " & cstrDecode End With ' Close class Set mclsUUEncode = Nothing End Sub Private Sub mclsUUEncode_FileProgress(dblPercentage As Double) ' Comments: This procedure captures the Progress Event and reveals the percentage completion for the file that's being compressed or decoded. ' This example puts the percentage in a text box on the form so you can see the progress ' Params : dblPercentage Percent of completion between 0 and 1 Me.txtProgress = Format$(dblPercentage, "Percent") ' Give time so Access can refresh the screen DoEvents End Sub
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