ZipCrc DataFlex Reference Documentation
ZipCrc
Current Version: 10.1.2
Calculate a Zip CRC checksum for a file or in-memory data.
Object Creation
// (Dataflex programs use the 32-bit Chilkat ActiveX) Handle hoZipCrc
Get Create(RefClass(cComChilkatZipCrc)) to hoZipCrc
Properties
DebugLogFilePath
Procedure Set ComDebugLogFilePath String value
If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.
Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.
Possible causes of hangs include:
- A timeout property set to 0, indicating an infinite timeout.
- A hang occurring within an event callback in the application code.
- An internal bug in the Chilkat code causing the hang.
LastBinaryResult
This property is mainly used in SQL Server stored procedures to retrieve binary data from the last method call that returned binary data. It is only accessible if Chilkat.Global.KeepBinaryResult is set to True. This feature allows for the retrieval of large varbinary results in an SQL Server environment, which has restrictions on returning large data via method calls, though temp tables can handle binary properties.
topLastErrorHtml
Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastErrorText
Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
LastErrorXml
Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastMethodSuccess
Procedure Set ComLastMethodSuccess Boolean value
Indicates the success or failure of the most recent method call: True means success, False means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages.
topLastStringResult
In SQL Server stored procedures, this property holds the string return value of the most recent method call that returns a string. It is accessible only when Chilkat.Global.KeepStringResult is set to TRUE. SQL Server has limitations on string lengths returned from methods and properties, but temp tables can be used to access large strings.
LastStringResultLen
The length, in characters, of the string contained in the LastStringResult property.
topVerboseLogging
Procedure Set ComVerboseLogging Boolean value
If set to True, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is False. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.
topVersion
Methods
BeginStream
Provides a way to calculate a CRC by streaming the data a chunk at a time. An application would start by calling BeginStream. Then it would add data by calling MoreData for each additional chunk. After the last chunk has been processed, the EndStream method is called to return the CRC.
topCalculateCrc
Calculates a 32-bit CRC for in-memory byte data. This is the 32-bit CRC that would be found in a Zip file header if a file containing the data was added to a zip archive. Returns the CRC32 of the data.
topCrcBd
Calculates a CRC32 for the bytes contained in bd.
topCrcSb
Calculates a CRC32 for the string contained in sb. The charset is the byte representation to be used for the sb when calculating the CRC32. It can be utf-8, utf-16, windows-1252, iso-8859-1, or any of the character encodings (charsets) listed at the link below.
topCrcString
Calculates a CRC32 for a string. The charset is the byte representation to be used for the str when calculating the CRC32. It can be utf-8, utf-16, windows-1252, iso-8859-1, or any of the character encodings (charsets) listed at the link below.
topEndStream
Finalizes and returns the Zip CRC value calculated by calling BeginStream followed by multiple calls to MoreData.
topFileCrc
Calculates the CRC32 of a file. The data contained in the file is streamed for the calculation to keep the memory footprint small and constant. Returns the CRC32 of the file.
FileCrcAsync (1)
Creates an asynchronous task to call the FileCrc method with the arguments provided.
Returns null on failure
topLoadTaskCaller
MoreData
Adds additional data to the CRC currently being calculated. (See BeginStream for more information.)
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