CkZipCrc C++ Reference Documentation


Current Version:

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

Object Creation

// Local variable on the stack
CkZipCrc obj;

// Dynamically allocate/delete
CkZipCrc *pObj = new CkZipCrc();
// ...
delete pObj;


bool get_LastMethodSuccess(void);
void put_LastMethodSuccess(bool newVal);

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.

bool get_Utf8(void);
void put_Utf8(bool newVal);

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.



void BeginStream(void);

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.

unsigned long CalculateCrc(CkByteData &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.

unsigned long EndStream(void);

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

unsigned long FileCrc(const char *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.

FileCrcAsync (1)
CkTask *FileCrcAsync(const char *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.)

Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.

Note: The application is responsible for deleting (via the C++ delete operator) the object returned by this method.

Returns NULL on failure

void MoreData(CkByteData &data);

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

bool ToHex(int crc, CkString &outStr);
const char *toHex(int crc);

Converts a 32-bit integer to a hex string.

Returns true for success, false for failure.



To implement an event callback, your application would define and implement a class that inherits from CkBaseProgress. Your application can implement methods to override some or all of the default/empty method implementations of the CkBaseProgress base class.

For example:

  CkZipCrc zipcrc;

  MyZipCrcProgress callbackObj;


MyZipCrcProgress example:

#include "CkBaseProgress.h"

class MyZipCrcProgress : public CkBaseProgress {

    virtual ~MyZipCrcProgress();

    void AbortCheck(bool  *abort);

    void BinaryData(const void *data, unsigned int length);

    void PercentDone(int pctDone, bool  *abort);

    void ProgressInfo(const char *name, const char *value);

    void TaskCompleted(CkTask &task);

    void TextData(const char *data);

void AbortCheck(bool *abort);

Provides the opportunity for a method call to be aborted. The AbortCheck event is fired periodically based on the value of the HeartbeatMs property. If HeartbeatMs is 0, then no AbortCheck events will fire. As an example, to fire 5 AbortCheck events per second, set the HeartbeatMs property equal to 200.

void PercentDone(int pctDone, bool *abort);

Provides the percentage completed for any method that involves network communications or time-consuming processing (assuming it is a method where a percentage completion can be measured). This event is only fired when it is possible to know a percentage completion, and when it makes sense to express the operation as a percentage completed. The pctDone argument will have a value from 1 to 100. For operations (Chilkat method calls) that complete very quickly, the number of PercentDone callbacks will vary, but the final callback should have a value of 100. For long running operations, no more than one callback per percentage point will occur (for example: 1, 2, 3, ... 98, 99, 100).

The PercentDone callback counts as an AbortCheck event. For method calls that complete quickly such that PercentDone events fire, it may be that AbortCheck events don't fire because the opportunity to abort is already provided in the PercentDone callback. For time consuming operations, where the amount of time between PercentDone callbacks are long, AbortCheck callbacks may be used to allow for the operation to be aborted in a more responsive manner.

The abort output argument provides a means for aborting the operation. Setting it to true will cause the method to abort and return a failed status (or whatever return value indicates failure).

void ProgressInfo(const char *name, const char *value);

A general name/value event that provides information about what is happening during a method call. To find out what information is available, write code to handle this event and log the name/value pairs. Most are self-explanatory.

void TaskCompleted(CkTask &task);

Called in the background thread when an asynchronous task completes.