ZipCrc Python Reference Documentation

ZipCrc

Current Version: 10.0.0

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

Object Creation

obj = chilkat2.ZipCrc()

Properties

DebugLogFilePath
string DebugLogFilePath

If set to a file path, causes each Chilkat method or property call to automatically append it's LastErrorText to the specified log file. The information is appended such that if a hang or crash occurs, it is possible to see the context in which the problem occurred, as well as a history of all Chilkat calls up to the point of the problem. The VerboseLogging property can be set to provide more detailed information.

This property is typically used for debugging the rare cases where a Chilkat method call hangs or generates an exception that halts program execution (i.e. crashes). A hang or crash should generally never happen. The typical causes of a hang are:

  1. a timeout related property was set to 0 to explicitly indicate that an infinite timeout is desired,
  2. the hang is actually a hang within an event callback (i.e. it is a hang within the application code), or
  3. there is an internal problem (bug) in the Chilkat code that causes the hang.

More Information and Examples
top
LastErrorHtml
string LastErrorHtml (read-only)

Provides information in HTML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

top
LastErrorText
string LastErrorText (read-only)

Provides information in plain-text format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

top
LastErrorXml
string LastErrorXml (read-only)

Provides information in XML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

top
LastMethodSuccess
bool LastMethodSuccess

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.

top
VerboseLogging
bool VerboseLogging

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.

top
Version
string Version (read-only)

Version of the component/library, such as "9.5.0.94"

More Information and Examples
top

Methods

BeginStream
void 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.

top
CalculateCrc
int CalculateCrc(memoryview 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.

top
CrcBd
int CrcBd(BinData bd)
Introduced in version 9.5.0.75

Calculates a CRC32 for the bytes contained in bd.

top
CrcSb
int CrcSb(StringBuilder sb, string charset)
Introduced in version 9.5.0.75

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.

top
CrcString
int CrcString(string str, string charset)
Introduced in version 9.5.0.75

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.

top
EndStream
int EndStream()

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

top
FileCrc
int FileCrc(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.

More Information and Examples
top
FileCrcAsync (1)
Task FileCrcAsync(string 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

top
LoadTaskCaller
bool LoadTaskCaller(Task task)
Introduced in version 9.5.0.80

Loads the caller of the task's async method.

Returns True for success, False for failure.

top
MoreData
void MoreData(memoryview data)

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

top
ToHex
string ToHex(int crc)

Converts a 32-bit integer to a hex string.

Returns None on failure

top