ZipCrc Chilkat2 PHP Reference Documentation
ZipCrc
Current Version: 11.7.0
Markdown version of this page for AI tools (v 11.7.0) · all AI docs
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.
Object Creation
use Chilkat2\ZipCrc;
try {
$zipCrc = new ZipCrc();
// ... use $zipCrc ...
} catch (\Chilkat2\Exception $e) {
echo $e->getClass(), '::', $e->getMethod(), " failed\n";
echo $e->getMessage(), "\n"; // the LastErrorText of the failed call
}Creates the object. The optional array sets properties in order, as if assigned one by one (new ZipCrc(['VerboseLogging' => true, 'RaiseError' => false])); an unknown or read-only name throws Error. The class is defined by the chilkat2 extension (extension=chilkat2 in php.ini): there is no PHP file to include.
There is no close(): PHP frees the object when its last reference goes (unset($zipCrc), $zipCrc = null, or the end of the function or request). Objects returned by methods are independent and freed the same way. The class may be extended (class MyZipCrc extends \Chilkat2\ZipCrc); objects cannot be cloned or serialized.
When true (the default), a method that fails throws Chilkat2\Exception. When false, it returns false (or null) instead, and the reason is in LastErrorText. Objects returned by a method inherit the value of the object that returned them.
Errors
Chilkat2\Exception extends RuntimeException: getMessage() is the failed call's full LastErrorText, getClass() its class ('Chilkat2\ZipCrc') and getMethod() the method name. The object remains usable. Methods that look something up and find nothing return null without throwing (each such method says so), methods that answer a question (HasMember, IsUnlocked, ...) return a plain bool, and property reads and writes do not throw for Chilkat reasons.
Misuse always throws, whatever RaiseError is: a wrong argument type is a TypeError (exact types under declare(strict_types=1)), a missing or extra argument an ArgumentCountError, a string containing a NUL byte or an out-of-range integer a ValueError, and an unknown property (properties are case-sensitive) or a write to a read-only one an Error. Named arguments work with the parameter names shown.
Strings are passed and returned as UTF-8; binary data is a PHP string of bytes. Unlocking: call (new \Chilkat2\GlobalSettings())->UnlockBundle('...') once at startup.
Properties
DebugLogFilePath
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
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
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
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
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.
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.
Version
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.
ToHex
Converts a 32-bit integer to a hex string.
On failure it throws Chilkat2\Exception (or, with RaiseError set to false, returns null). $e->getMessage() (or the object's LastErrorText) explains why, and the object remains usable.
Events
All Chilkat methods are synchronous: the call returns when the work is done. During a long-running call, ZipCrc reports progress to handlers installed with three methods, each taking any PHP callable (a closure, an arrow function, $this->method(...), an invokable object) and returning the object, so the calls chain:
$zipCrc->onPercentDone(function (int $pctDone): bool {
echo "$pctDone%\n";
return false; // return true to abort the method in progress
})
->onProgressInfo(function (string $name, string $value): void {
echo "$name: $value\n";
});Each installs the handler for one event, replacing the one installed before; null removes it. A callable that does not exist is a TypeError right away.
The AbortCheck handler is called periodically during long operations; PercentDone is called when an operation's completion percentage is known; ProgressInfo delivers named progress values. A truthy return from the AbortCheck or PercentDone handler aborts the running method, which then fails in the usual way (Chilkat2\Exception, or false / null with RaiseError off). PHP's set_time_limit() does not interrupt a Chilkat call; an AbortCheck handler is how a script enforces its own limit.
Handlers run during the method call, in the same request. Inside a handler, the object's properties (such as $zipCrc->AbortCurrent = true) and other objects may be used, but calling a method of the same object throws Error. An exception thrown by a handler aborts the running method and propagates from it; the object remains usable. A closure that captures $zipCrc itself makes a reference cycle, which PHP's cycle collector frees.
AbortCheck
public function onAbortCheck(?callable $callback): static
Enables a method call to be aborted by triggering the AbortCheck event at intervals defined by the HeartbeatMs property. If HeartbeatMs is set to its default value of 0, no events will occur. For instance, set HeartbeatMs to 200 to trigger 5 AbortCheck events per second.
Example
$deadline = microtime(true) + 30; // give up after 30 seconds
$zipCrc->onAbortCheck(fn(): bool => microtime(true) > $deadline);PercentDone
public function onPercentDone(?callable $callback): static
This provides the percentage completion for any method involving network communications or time-consuming processing, assuming the progress can be measured as a percentage. This event is triggered only when it's possible and logical to express the operation's progress as a percentage. The pctDone argument will range from 1 to 100. For methods that finish quickly, the number of PercentDone callbacks may vary, but the final callback will have pctDone equal to 100. For longer operations, callbacks will not exceed one per percentage point (e.g., 1, 2, 3, ..., 98, 99, 100).
The PercentDone callback also acts as an AbortCheck event. For fast methods where PercentDone fires, an AbortCheck event may not trigger since the PercentDone callback already provides an opportunity to abort. For longer operations, where time between PercentDone callbacks is extended, AbortCheck callbacks enable more responsive operation termination.
To abort the operation, set the abort output argument to true. This will cause the method to terminate and return a failure status or corresponding failure value.
Example
$zipCrc->onPercentDone(function (int $pctDone): bool {
// $pctDone ranges from 0 to 100.
echo "Percent done: $pctDone\n";
return false; // return true to abort the method in progress
});ProgressInfo
public function onProgressInfo(?callable $callback): static
This event callback provides tag name/value pairs that detail what occurs during a method call. To discover existing tag names, create code to handle the event, emit the pairs, and review them. Most tag names are self-explanatory.
Note: Some Chilkat methods don't fire any ProgressInfo events.
Example
$zipCrc->onProgressInfo(function (string $name, string $value): void {
echo "$name: $value\n";
});