ZipCrc DataFlex Reference Documentation

ZipCrc

Calculate a Zip CRC checksum for a file or in-memory data.

Object Creation

Handle hoZipCrc
Get Create(RefClass(cComChilkatZipCrc)) to hoZipCrc

Properties

Function ComLastMethodSuccess Returns Boolean
Procedure Set ComLastMethodSuccess Boolean value

Introduced in version 9.5.0.52

Indicate whether the last method call succeeded or failed. A value of True indicates success, a value of False indicates failure. This property is automatically set for method calls. It is not modified by property accesses. The property is automatically set to indicate success for the following types of method calls:

  • Any method that returns a string.
  • Any method returning a Chilkat object, binary bytes, or a date/time.
  • Any method returning a standard boolean status value where success = True and failure = False.
  • Any method returning an integer where failure is defined by a return value less than zero.

Note: Methods that do not fit the above requirements will always set this property equal to True. For example, a method that returns no value (such as a "void" in C++) will technically always succeed.

Methods

Procedure ComBeginStream

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.

Function ComCalculateCrc Variant data

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.

Function ComEndStream

Finalizes and returns the Zip CRC value calculated by calling BeginStream followed by multiple calls to MoreData.

Function ComFileCrc String path

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.

Function ComFileCrcAsync String path Returns cComChilkatTask

Creates an asynchronous task to call the FileCrc method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns null on failure

How to Run an Asynchronous Task

Procedure ComMoreData Variant data

Adds additional data to the CRC currently being calculated. (See BeginStream for more information.)

Function ComToHex Integer crc Returns String

Converts a 32-bit integer to a hex string.

Returns null on failure