---
product: Chilkat
product_version: 11.7.0
language: tcl
language_label: Tcl
class: ZipCrc
license: bundle
deprecated: false
reference_html: https://www.chilkatsoft.com/refdoc/tclZipCrcRef.html
---
# Chilkat ZipCrc — Tcl — v11.7.0

> Chilkat 11.7.0 · language=tcl · class=ZipCrc
> Other versions: replace `11.7.0` in this URL. Other languages: `https://www.chilkatsoft.com/ai-docs/v/11.7.0/<lang>/classes/ZipCrc.md`.
> Language-wide rules (install, unlock, error model, strings/bytes): `https://www.chilkatsoft.com/ai-docs/v/11.7.0/tcl/guide.md`.

## Purpose

**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**

Use `CalculateCrc` to calculate a ZIP-style CRC32 value for an in-memory byte array.

**BinData support**

Use `CrcBd` when the input bytes are already stored in a `Chilkat.BinData` object.

**String CRCs**

Use `CrcString` or `CrcSb` to calculate CRC32 for text using a specific charset such as `utf-8`, `utf-16`, or `windows-1252`.

**File CRCs**

Use `FileCrc` to calculate the CRC32 of a file while streaming the file contents to keep memory usage small and constant.

**Streaming calculation**

Call `BeginStream`, add chunks with `MoreData`, and finish with `EndStream` when data arrives incrementally.

**Hex formatting**

Use `ToHex` to convert a 32-bit CRC integer into a readable hexadecimal string.

**Common pattern:** Use `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.

**ZIP compatibility note:** The CRC returned by this class is the same 32-bit CRC value that would appear in a ZIP file header for the same byte content. When calculating CRCs for strings, the selected charset matters because the CRC is computed over bytes, not abstract characters.

## Object creation, unlocking and error handling

**Object Creation**

```tcl
# 'this' is not a keyword in Tcl. It can freely be used as a variable name.
set this [new CkZipCrc]
```

Call `Global.UnlockBundle` once at the start of the program, before using this or any other Chilkat class. Any string unlocks a fully functional 30-day trial; a purchased unlock code is used in production. See `guide.md` for the exact code in Tcl.

How failure is reported depends on the method's return type and is stated in the note under each method below. In every case the diagnostic text is in the `LastErrorText` property of the object whose method was called.

## Members common to every Chilkat class

Documented once per language in `common-members.md`; listed here so this page is self-contained.

| Property | Signature | Access | Meaning |
|---|---|---|---|
| `DebugLogFilePath` | `string # ckStr is a CkString CkZipCrc_get_DebugLogFilePath $this $ckStr set strVal [CkZipCrc_get_debugLogFilePath $this] CkZipCrc_put_DebugLogFilePath $this $strVal` | read/write | If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. |
| `LastErrorHtml` | `string # ckStr is a CkString CkZipCrc_get_LastErrorHtml $this $ckStr set strVal [CkZipCrc_get_lastErrorHtml $this]` | read-only | Provides HTML-formatted information about the last called method or property. |
| `LastErrorText` | `string # ckStr is a CkString CkZipCrc_get_LastErrorText $this $ckStr set strVal [CkZipCrc_get_lastErrorText $this]` | read-only | Provides plain text information about the last called method or property. |
| `LastErrorXml` | `string # ckStr is a CkString CkZipCrc_get_LastErrorXml $this $ckStr set strVal [CkZipCrc_get_lastErrorXml $this]` | read-only | Provides XML-formatted information about the last called method or property. |
| `LastMethodSuccess` | `boolean 1/0 set boolVal [CkZipCrc_get_LastMethodSuccess $this] CkZipCrc_put_LastMethodSuccess $this $boolVal` | read/write | Indicates the success or failure of the most recent method call: `1` means success, `0` means failure. |
| `Utf8` | `boolean 1/0 set boolVal [CkZipCrc_get_Utf8 $this] CkZipCrc_put_Utf8 $this $boolVal` | read/write | When set to `1`, all `string` arguments and return values are interpreted as UTF-8 strings. |
| `VerboseLogging` | `boolean 1/0 set boolVal [CkZipCrc_get_VerboseLogging $this] CkZipCrc_put_VerboseLogging $this $boolVal` | read/write | If set to `1`, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. |
| `Version` | `string # ckStr is a CkString CkZipCrc_get_Version $this $ckStr set strVal [CkZipCrc_get_version $this]` | read-only | Version of the component/library, such as "10.1.0" |

## Member index

| Member | Kind | Signature |
|---|---|---|
| `BeginStream` | method | `CkZipCrc_BeginStream $this` |
| `CrcBd` | method | `# bd is a CkBinData set retInt [CkZipCrc_CrcBd $this $bd]` |
| `CrcSb` | method | `# sb is a CkStringBuilder # charset is a string set retInt [CkZipCrc_CrcSb $this $sb $charset]` |
| `CrcString` | method | `# str is a string # charset is a string set retInt [CkZipCrc_CrcString $this $str $charset]` |
| `EndStream` | method | `set retInt [CkZipCrc_EndStream $this]` |
| `FileCrc` | method | `# path is a string set retInt [CkZipCrc_FileCrc $this $path]` |
| `LoadTaskCaller` | method | `# task is a CkTask set status [CkZipCrc_LoadTaskCaller $this $task]` |
| `ToHex` | method | `# crc is an integer # outStr is a CkString (output) set status [CkZipCrc_ToHex $this $crc $outStr] set retStr [CkZipCrc_toHex $this $crc]` |

Deprecated members are listed at the end of this file with their replacements; do not use them in new code.

## Methods

### ZipCrc.BeginStream

`Chilkat 11.7.0 · tcl · ZipCrc · BeginStream · method`

```tcl
CkZipCrc_BeginStream $this
```

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.

### ZipCrc.CrcBd

`Chilkat 11.7.0 · tcl · ZipCrc · CrcBd · method · since 9.5.0.75`

```tcl
# bd is a CkBinData

set retInt [CkZipCrc_CrcBd $this $bd]
```

Calculates a CRC32 for the bytes contained in `bd`.

### ZipCrc.CrcSb

`Chilkat 11.7.0 · tcl · ZipCrc · CrcSb · method · since 9.5.0.75`

```tcl
# sb is a CkStringBuilder

# charset is a string

set retInt [CkZipCrc_CrcSb $this $sb  $charset]
```

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.

### ZipCrc.CrcString

`Chilkat 11.7.0 · tcl · ZipCrc · CrcString · method · since 9.5.0.75`

```tcl
# str is a string

# charset is a string

set retInt [CkZipCrc_CrcString $this $str  $charset]
```

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.

### ZipCrc.EndStream

`Chilkat 11.7.0 · tcl · ZipCrc · EndStream · method`

```tcl
set retInt [CkZipCrc_EndStream $this]
```

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

### ZipCrc.FileCrc

`Chilkat 11.7.0 · tcl · ZipCrc · FileCrc · method`

```tcl
# path is a string

set retInt [CkZipCrc_FileCrc $this $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.

Async variant: `FileCrcAsync` — same arguments, returns a `Task` (see Async variants below).

### ZipCrc.LoadTaskCaller

`Chilkat 11.7.0 · tcl · ZipCrc · LoadTaskCaller · method · since 9.5.0.80`

```tcl
# task is a CkTask

set status [CkZipCrc_LoadTaskCaller $this $task]
```

Loads the caller of the task's async method.

Returns 1 for success, 0 for failure.

### ZipCrc.ToHex

`Chilkat 11.7.0 · tcl · ZipCrc · ToHex · method`

```tcl
# crc is an integer

# outStr is a CkString (output)

set status [CkZipCrc_ToHex $this $crc $outStr]

set retStr [CkZipCrc_toHex $this $crc]
```

Converts a 32-bit integer to a hex string.

Returns 1 for success, 0 for failure.

## Events and callbacks

This binding has no event callbacks. For progress, percent-done or cancellation use the `*Async` variant of a method and poll the returned `Task` (`PercentDone`, `Finished`, `Cancel`).

## Async variants

Each returns a `Task` instead of the result and takes the same arguments as the synchronous method; run the task, wait for `Finished`, then read the result from the task. No new Async methods are added from 11.7.0 on.

```tcl
# returns a CkTask

# path is a string

set ret_task [CkZipCrc_FileCrcAsync $this $path]
```

## Deprecated members — do not use in new code

| Member | Kind | Deprecated in | Use instead |
|---|---|---|---|
| `CalculateCrc` | method | before 11.6.1 | — |
| `MoreData` | method | before 11.6.1 | — |

## Related classes

[`BinData`](https://www.chilkatsoft.com/ai-docs/v/11.7.0/tcl/classes/BinData.md), [`StringBuilder`](https://www.chilkatsoft.com/ai-docs/v/11.7.0/tcl/classes/StringBuilder.md), [`Task`](https://www.chilkatsoft.com/ai-docs/v/11.7.0/tcl/classes/Task.md)