ZipCrc C Reference Documentation
ZipCrc
Current Version: 11.6.0
Chilkat.ZipCrc
Use
Use
Use
Use
Call
Use Calculate ZIP-compatible CRC32 values for files, bytes, strings, and streamed data.
Chilkat.ZipCrc calculates the 32-bit CRC value used in ZIP file
headers. It can compute CRC32 values for in-memory byte arrays,
BinData, StringBuilder content, strings using a
specified character encoding, and entire files. It also supports streaming
CRC calculation, allowing applications to process large or incremental data
in chunks without holding the full input in memory.
CRC32 for byte data
CalculateCrc to calculate a ZIP-style CRC32 value for
an in-memory byte array.
BinData support
CrcBd when the input bytes are already stored in a
Chilkat.BinData object.
String CRCs
CrcString or CrcSb to calculate CRC32 for
text using a specific charset such as utf-8,
utf-16, or windows-1252.
File CRCs
FileCrc to calculate the CRC32 of a file while streaming
the file contents to keep memory usage small and constant.
Streaming calculation
BeginStream, add chunks with MoreData, and
finish with EndStream when data arrives incrementally.
Hex formatting
ToHex to convert a 32-bit CRC integer into a readable
hexadecimal string.
FileCrc for files, CalculateCrc or
CrcBd for binary data already in memory, and
CrcString or CrcSb for text where the byte
representation depends on a charset. For large or chunked input, initialize
the CRC with BeginStream, feed each block with
MoreData, and call EndStream to obtain the final
CRC32 value.
Create/Dispose
HCkZipCrc instance = CkZipCrc_Create();
// ...
CkZipCrc_Dispose(instance);Creates an instance of the HCkZipCrc object and returns a handle ("void *" pointer). The handle is passed in the 1st argument for the functions listed on this page.
Objects created by calling CkZipCrc_Create must be freed by calling this method. A memory leak occurs if a handle is not disposed by calling this function. Also, any handle returned by a Chilkat "C" function must also be freed by the application by calling the appropriate Dispose method, such as CkZipCrc_Dispose.
Callback Functions
void CkZipCrc_setAbortCheck(HCkHttp cHandle, BOOL (*fnAbortCheck)(void));
Gives your application a chance to cancel a method call while it is running. Return TRUEFALSE
This callback fires periodically, at the interval set by the HeartbeatMs property. For example, set HeartbeatMs to 200 to receive five AbortCheck callbacks per second. If HeartbeatMs is 0, no callbacks are made and the operation cannot be aborted.
void CkZipCrc_setPercentDone(HCkHttp cHandle, BOOL (*fnPercentDone)(int pctDone));
Reports how far along a method call is, as a percentage. It applies to methods that involve network communication or time-consuming processing, and fires only when a percentage completed can actually be measured and it makes sense to express progress that way.
The pctDone argument is a value from 1 to 100. Methods that finish very quickly may produce only a few callbacks, but the final callback always reports 100. Long-running operations produce at most one callback per percentage point (for example: 1, 2, 3, … 98, 99, 100).
This callback also counts as an AbortCheck callback. When PercentDone fires, it replaces the AbortCheck callback that would otherwise have occurred at that moment.
The return value controls whether the method call continues. Return TRUEFALSE
void CkZipCrc_setProgressInfo(HCkHttp cHandle, void (*fnProgressInfo)(const char *name, const char *value));
A general-purpose callback that reports name/value pairs describing what is happening at various points during a method call. The information provided varies by method, and some methods provide none at all. To see what a particular method reports, write a handler that logs each name/value pair. Most are self-explanatory.
void CkZipCrc_setTaskCompleted(HCkHttp cHandle, void (*fnTaskCompleted)(HCkTask hTask));
Called when an asynchronous task finishes. This callback runs in the background thread rather than the thread that started the task. (While an async method is running, all callbacks occur in the background thread.)
Properties
DebugLogFilePath
void CkZipCrc_putDebugLogFilePath(HCkZipCrc cHandle, const char *newVal);
const char *CkZipCrc_debugLogFilePath(HCkZipCrc cHandle);
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.
LastErrorHtml
const char *CkZipCrc_lastErrorHtml(HCkZipCrc cHandle);
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
const char *CkZipCrc_lastErrorText(HCkZipCrc cHandle);
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
const char *CkZipCrc_lastErrorXml(HCkZipCrc cHandle);
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
void CkZipCrc_putLastMethodSuccess(HCkZipCrc cHandle, BOOL newVal);
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. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.
Utf8
void CkZipCrc_putUtf8(HCkZipCrc cHandle, BOOL newVal);
When set to TRUE, all const char * arguments and return values are interpreted as UTF-8 strings. When set to FALSE, they are interpreted as ANSI strings.
In Chilkat v11.0.0 and later, the default value is TRUE. Before v11.0.0, it was FALSE.
VerboseLogging
void CkZipCrc_putVerboseLogging(HCkZipCrc cHandle, BOOL newVal);
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.
Version
const char *CkZipCrc_version(HCkZipCrc cHandle);
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.
topCrcBd
Calculates a CRC32 for the bytes contained in bd.
CrcSb
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.
CrcString
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.
EndStream
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
LoadTaskCaller
ToHex
const char *CkZipCrc_toHex(HCkZipCrc cHandle, unsigned long crc);
Deprecated
CalculateCrc Deprecated
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.
MoreData Deprecated
Adds additional data to the CRC currently being calculated. (See BeginStream for more information.)
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