CkZipCrc Python Reference Documentation

CkZipCrc

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

Object Creation

obj = chilkat.CkZipCrc()

Properties

# boolVal is a boolean
boolVal = zipCrc.get_LastMethodSuccess();
zipCrc.put_LastMethodSuccess(boolVal);

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.

# boolVal is a boolean
boolVal = zipCrc.get_Utf8();
zipCrc.put_Utf8(boolVal);

When set to True, all "const char *" arguments are interpreted as utf-8 strings. If set to False (the default), then "const char *" arguments are interpreted as ANSI strings. Also, when set to True, and Chilkat method returning a "const char *" is returning the utf-8 representation. If set to False, all "const char *" return values are ANSI strings.

Methods

zipCrc.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.

# data is a CkByteData
retInt = zipCrc.CalculateCrc(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.

retInt = zipCrc.EndStream();

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

# path is a string
retInt = zipCrc.FileCrc(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.

# returns a CkTask
# path is a string
ret_task = zipCrc.FileCrcAsync(path);

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 None on failure

How to Run an Asynchronous Task

# data is a CkByteData
zipCrc.MoreData(data);

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

# crc is an integer
# outStr is a CkString (output)
status = zipCrc.ToHex(crc, outStr);
retStr = zipCrc.toHex(crc);

Converts a 32-bit integer to a hex string.

Returns True for success, False for failure.