Charset Rust Reference Documentation

Charset

Current Version: 11.6.1
Requires Chilkat Bundle License

Deprecated — scheduled for removal

Legacy character-set conversion utilities. Migrate before Chilkat v12.0.0.

Do not use Chilkat.Charset in new development. The entire class is deprecated and is scheduled to be removed in Chilkat v12.0.0. Existing applications should migrate now. Equivalent functionality is available in the free Chilkat.BinData and Chilkat.StringBuilder classes.

Chilkat.Charset is a legacy class for converting text between character encodings, reading and writing encoded text files, inspecting or rewriting HTML charset declarations, encoding and decoding HTML entities, validating byte sequences, and performing several older text utilities. It remains documented only to support maintenance and migration of existing applications.

Use BinData for bytes

Store raw bytes, load and save files, append byte-order marks, and move encoded data between files, memory, and other Chilkat objects.

Use StringBuilder for text

Hold Unicode text and perform charset encoding or decoding, URL processing, HTML entity conversion, case conversion, and related text operations.

Prefer UTF-8

For new text formats and interchange, use UTF-8 unless a protocol or legacy system explicitly requires another encoding.

Keep bytes and characters distinct

A charset defines how text characters map to bytes. Binary encodings such as Base64 or hexadecimal solve a different problem and are not character sets.

Legacy HTML helpers

The class can inspect and rewrite HTML charset metadata, but these helpers do not validate that declared metadata matches the actual bytes.

Maintenance only

Continue using this class only while maintaining older code, and plan a tested migration before adopting Chilkat v12.

Migration pattern: load encoded bytes into BinData, decode them into a StringBuilder using the known source charset, work with Unicode text, then encode back into BinData using the required destination charset. This makes the boundary between bytes and text explicit and replaces the stateful FromCharset/ToCharset workflow.

Object Creation

// Cargo.toml:
//     [dependencies]
//     chilkat = "11.6"

use chilkat::Charset;

// Once per process, before any other Chilkat call:
chilkat::unlock_bundle("Anything for 30-day trial")?;  // shorthand for Global::new().unlock_bundle(..)

let charset = Charset::new();
// ... the native object is freed when `charset` goes out of scope.
pub fn new() -> Charset

Creates the underlying native Chilkat object (Charset also implements Default). Every method takes &self, so the object never needs to be declared mut. A Charset is Send but not Sync: it may be moved to another thread, but a reference to it cannot be shared between threads at the same time.

impl Drop for Charset

The native object is freed when the Charset is dropped — when it goes out of scope, or explicitly with drop(charset). There is no Dispose method to call.

Errors

Methods that can fail return chilkat::Result<T>, which is Result<T, chilkat::Error>: a method whose only outcome is success or failure returns Result<()>, a method producing a string or an object returns Result<String> or Result<Charset>. The error carries the object's LastErrorText at the time of the failure (Error::last_error_text), the class and method names, and implements std::error::Error, so ? works in any function returning chilkat::Result or a Box<dyn Error>. Properties never fail, and methods that answer a question (has_..., is_..., ...) return a plain bool.

match charset.some_method(...) {
    Ok(value) => println!("{value:?}"),
    Err(e) => eprintln!("{}", e.last_error_text()),
}

Properties

AltToCharset
// read/write
pub fn alt_to_charset(&self) -> String
pub fn set_alt_to_charset(&self, value: &str)

Specifies the alternate destination character encoding used only when ErrorAction is 6.

If a decoded input character cannot be represented in ToCharset, Chilkat attempts to encode that character using this alternate charset. If the alternate conversion also fails, the character is omitted from the output.

Mixed-encoding output: The result can contain a mixture of byte encodings. Such output is usually unsuitable for interchange unless the receiving format explicitly supports this behavior.

top
DebugLogFilePath
// read/write
pub fn debug_log_file_path(&self) -> String
pub fn set_debug_log_file_path(&self, value: &str)

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.

More Information and Examples
Example showing how to use DebugLogFilePath.
top
ErrorAction
// read/write
pub fn error_action(&self) -> i32
pub fn set_error_action(&self, value: i32)

Controls what happens when an input character has been decoded successfully but cannot be represented in the destination charset.

ValueAction
0Drop the unrepresentable character.
1Insert the replacement configured by SetErrorString.
2Emit a hexadecimal numeric character reference such as &#x20AC;.
3–5Reserved. Do not use.
6Encode the character using AltToCharset; drop it if that also fails.
7Pass the nonconvertible data through unchanged.
Data-integrity warning: Values 0, 6, and 7 can silently lose data or produce output that is not valid in the declared destination charset. For new code, prefer an explicit failure or replacement policy in the replacement API.

top
FromCharset
// read/write
pub fn from_charset(&self) -> String
pub fn set_from_charset(&self, value: &str)

Specifies the character encoding of the input bytes for conversion operations. Chilkat decodes the source bytes using this charset before encoding the resulting Unicode text using ToCharset.

FamilyRecognized names
Unicode and ASCIIus-ascii, utf-7, utf-8, unicode / utf-16 / utf-16le, unicodefffe / utf-16be, utf-32, utf-32be
ISO and Windowsiso-8859-1, -2, -3, -4, -5, -6, -7, -8, -9, -13, -15; windows-874, windows-1250 through windows-1258
East Asianshift_jis, gb2312, ks_c_5601-1987, big5, iso-2022-jp, iso-2022-kr, euc-jp, euc-kr
Macintoshmacintosh, x-mac-japanese, x-mac-chinesetrad, x-mac-korean, x-mac-arabic, x-mac-hebrew, x-mac-greek, x-mac-cyrillic, x-mac-chinesesimp, x-mac-romanian, x-mac-ukrainian, x-mac-thai, x-mac-ce, x-mac-icelandic, x-mac-turkish, x-mac-croatian
DOS, IBM, and legacyebcdic, asmo-708, dos-720, dos-862, ibm01140 through ibm01149, ibm037, ibm437, ibm500, ibm737, ibm775, ibm850, ibm852, ibm855, ibm857, ibm00858, ibm860, ibm861, ibm863, ibm864, ibm865, cp866, ibm869, ibm870, cp875, koi8-r, koi8-u
Source encoding: unicode, utf-16, and utf-16le identify little-endian UTF-16. unicodefffe and utf-16be identify big-endian UTF-16. Except where a method explicitly documents HTML metadata detection, set the source charset explicitly rather than assuming automatic detection.

top
LastErrorHtml
// read-only
pub fn last_error_html(&self) -> String

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.

top
LastErrorText
// read-only
pub fn last_error_text(&self) -> String

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.

More Information and Examples
Concept of LastErrorTextLastErrorText Standard Information
top
LastErrorXml
// read-only
pub fn last_error_xml(&self) -> String

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.

top
LastInputAsHex
// read-only
pub fn last_input_as_hex(&self) -> String

Returns the input bytes captured for the most recent conversion performed while SaveLast was enabled, represented as hexadecimal text.

Diagnostic snapshot: This is a diagnostic representation of the raw bytes. It does not perform another charset conversion, and the quoted-printable form is intended to make otherwise nonprintable bytes easier to inspect.

top
LastInputAsQP
// read-only
pub fn last_input_as_qp(&self) -> String

Returns the input bytes captured for the most recent conversion performed while SaveLast was enabled, represented as quoted-printable text.

Diagnostic snapshot: This is a diagnostic representation of the raw bytes. It does not perform another charset conversion, and the quoted-printable form is intended to make otherwise nonprintable bytes easier to inspect.

top
LastMethodSuccess
// read/write
pub fn last_method_success(&self) -> bool
pub fn set_last_method_success(&self, value: bool)

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.

top
LastOutputAsHex
// read-only
pub fn last_output_as_hex(&self) -> String

Returns the output bytes captured for the most recent conversion performed while SaveLast was enabled, represented as hexadecimal text.

Diagnostic snapshot: This is a diagnostic representation of the raw bytes. It does not perform another charset conversion, and the quoted-printable form is intended to make otherwise nonprintable bytes easier to inspect.

top
LastOutputAsQP
// read-only
pub fn last_output_as_qp(&self) -> String

Returns the output bytes captured for the most recent conversion performed while SaveLast was enabled, represented as quoted-printable text.

Diagnostic snapshot: This is a diagnostic representation of the raw bytes. It does not perform another charset conversion, and the quoted-printable form is intended to make otherwise nonprintable bytes easier to inspect.

top
SaveLast
// read/write
pub fn save_last(&self) -> bool
pub fn set_save_last(&self, value: bool)

When true, retains the input and output byte sequences from each conversion so they can be inspected through LastInputAsHex, LastInputAsQP, LastOutputAsHex, and LastOutputAsQP.

Debugging only: Enable this only while troubleshooting. Retaining both sides of a large conversion increases memory use and may keep sensitive plaintext in memory longer than necessary.

top
ToCharset
// read/write
pub fn to_charset(&self) -> String
pub fn set_to_charset(&self, value: &str)

Specifies the destination character encoding for conversion operations. After decoding the source bytes using FromCharset, Chilkat encodes the resulting Unicode text in this charset.

FamilyRecognized names
Unicode and ASCIIus-ascii, utf-7, utf-8, unicode / utf-16 / utf-16le, unicodefffe / utf-16be, utf-32, utf-32be
ISO and Windowsiso-8859-1, -2, -3, -4, -5, -6, -7, -8, -9, -13, -15; windows-874, windows-1250 through windows-1258
East Asianshift_jis, gb2312, ks_c_5601-1987, big5, iso-2022-jp, iso-2022-kr, euc-jp, euc-kr
Macintoshmacintosh, x-mac-japanese, x-mac-chinesetrad, x-mac-korean, x-mac-arabic, x-mac-hebrew, x-mac-greek, x-mac-cyrillic, x-mac-chinesesimp, x-mac-romanian, x-mac-ukrainian, x-mac-thai, x-mac-ce, x-mac-icelandic, x-mac-turkish, x-mac-croatian
DOS, IBM, and legacyebcdic, asmo-708, dos-720, dos-862, ibm01140 through ibm01149, ibm037, ibm437, ibm500, ibm737, ibm775, ibm850, ibm852, ibm855, ibm857, ibm00858, ibm860, ibm861, ibm863, ibm864, ibm865, cp866, ibm869, ibm870, cp875, koi8-r, koi8-u
Choosing an output encoding: For new text interchange, utf-8 is normally the preferred destination. Legacy single-byte encodings cannot represent every Unicode character; ErrorAction controls how such conversion failures are handled.

top
VerboseLogging
// read/write
pub fn verbose_logging(&self) -> bool
pub fn set_verbose_logging(&self, value: bool)

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
// read-only
pub fn version(&self) -> String

Version of the component/library, such as "10.1.0"

More Information and Examples
How to get the Chilkat version at runtime.
top

Methods

CharsetToCodePage
pub fn charset_to_code_page(&self, charset_name: &str) -> i32

Returns the numeric Windows code-page identifier corresponding to charset_name. For example, iso-8859-1 maps to 28591, and utf-8 maps to 65001.

Code pages: A code page number is a legacy Windows identifier for a character encoding. Internet protocols and modern APIs normally use charset names such as utf-8 rather than numeric code pages.
top
CodePageToCharset
pub fn code_page_to_charset(&self, code_page: i32) -> Result<String>

Returns the charset name corresponding to the numeric code-page identifier in code_page. For example, 65001 maps to utf-8. The operation fails when the code page is not recognized.

Name normalization: Different aliases can identify the same encoding. The returned value is Chilkat’s canonical name for the recognized code page, not necessarily the alias originally used by another application.

Returns Err(chilkat::Error) on failure.

top
ConvertFile
pub fn convert_file(&self, in_path: &str, dest_path: &str) -> Result<()>

Reads the file at in_path, converts its text from FromCharset to ToCharset, and writes the converted bytes to the file at dest_path.

When the destination charset is utf-8 or utf-16, this method writes the corresponding byte-order mark (BOM) at the beginning of the output. Use ConvertFileNoPreamble when the output must not contain a BOM.

BOM behavior: A BOM is a leading byte sequence that can identify a Unicode encoding or byte order. UTF-8 does not require a BOM, and many modern formats prefer UTF-8 without one.

Returns Ok(()) for success, Err(chilkat::Error) for failure.

More Information and Examples
Convert a File's Character Encoding from UTF-8 to UFT-8-BOM
top
ConvertFileNoPreamble
pub fn convert_file_no_preamble(&self, in_path: &str, dest_path: &str) -> Result<()>

Reads the file at in_path, converts its text from FromCharset to ToCharset, and writes the converted bytes to dest_path without adding a byte-order mark or other encoding preamble.

UTF-8 output: This is generally the appropriate choice for UTF-8 files unless the consuming system specifically requires a UTF-8 BOM.

Returns Ok(()) for success, Err(chilkat::Error) for failure.

top
ConvertHtmlFile
pub fn convert_html_file(&self, in_path: &str, dest_path: &str) -> Result<()>

Converts the HTML file at in_path to ToCharset and writes the result to dest_path. Chilkat also updates the HTML <meta> charset declaration to identify the destination encoding.

If FromCharset is empty, Chilkat attempts to obtain the source charset from an HTML <meta> declaration. Otherwise, the explicitly configured source charset is used.

Detection limitation: A declared charset is metadata, not proof of the file’s actual encoding. Incorrect or missing declarations can cause decoding errors; use an explicit source charset when it is known.

Returns Ok(()) for success, Err(chilkat::Error) for failure.

top
EntityEncodeDec
pub fn entity_encode_dec(&self, str: &str) -> Result<String>

Returns str with each non-US-ASCII character replaced by a decimal HTML/XML numeric character reference. For example, é becomes &#233;.

Entity encoding: Numeric character references describe Unicode characters; they are not a character-set conversion and do not make arbitrary binary data safe for HTML.

Returns Err(chilkat::Error) on failure.

top
EntityEncodeHex
pub fn entity_encode_hex(&self, str: &str) -> Result<String>

Returns str with each non-US-ASCII character replaced by a hexadecimal HTML/XML numeric character reference. For example, é becomes &#xE9;.

Entity encoding: Decimal and hexadecimal numeric references represent the same Unicode character; only the textual notation differs.

Returns Err(chilkat::Error) on failure.

top
GetHtmlFileCharset
pub fn get_html_file_charset(&self, html_file_path: &str) -> Result<String>

Examines the HTML file at html_file_path and returns the charset name declared by an HTML <meta> element, when present.

Metadata only: The method reads document metadata only. A missing, stale, or incorrect declaration does not reveal the file’s true encoding.

Returns Err(chilkat::Error) on failure.

top
HtmlDecodeToStr
pub fn html_decode_to_str(&self, in_str: &str) -> Result<String>

Decodes HTML named entities and numeric character references in in_str and returns the resulting Unicode string. Examples include &lt;, &amp;, &#233;, and &#xE9;.

Security context: Entity decoding is a text transformation, not HTML parsing or sanitization. Decoding untrusted text can reintroduce markup-significant characters such as <, >, and &.

Returns Err(chilkat::Error) on failure.

top
HtmlEntityDecodeFile
pub fn html_entity_decode_file(&self, in_path: &str, dest_path: &str) -> Result<()>

Reads the file at in_path, decodes HTML named entities and numeric character references, and writes the transformed content to dest_path.

Content transformation: The output may contain literal markup-significant characters that were previously escaped. This operation does not parse, validate, or sanitize HTML.

Returns Ok(()) for success, Err(chilkat::Error) for failure.

top
LowerCase
pub fn lower_case(&self, in_str: &str) -> Result<String>

Returns the lowercase form of in_str using Chilkat’s Unicode case conversion.

Unicode casing: Case conversion can change string length and is not the same operation as locale-aware collation or case-insensitive comparison.

Returns Err(chilkat::Error) on failure.

top
ReadFileToString
pub fn read_file_to_string(&self, path: &str, charset: &str) -> Result<String>

Reads the text file at path, decodes its bytes using the charset named by charset, and returns the resulting Unicode string.

Charset must match the file: The caller must supply the actual source encoding. Choosing the wrong charset can produce replacement characters or silently incorrect text even when the file can be decoded.

Returns Err(chilkat::Error) on failure.

top
SetErrorString
pub fn set_error_string(&self, str: &str, charset: &str)

Configures the replacement used when ErrorAction is 1. str is the replacement text, and charset identifies the charset used to encode that replacement into the conversion output.

Replacement behavior: Choose replacement text that is representable in the specified charset. A common replacement is ?, but explicit error handling is safer when data loss is unacceptable.
top
UpperCase
pub fn upper_case(&self, in_str: &str) -> Result<String>

Returns the uppercase form of in_str using Chilkat’s Unicode case conversion.

Unicode casing: Case conversion can change string length and is not the same operation as locale-aware collation or case-insensitive comparison.

Returns Err(chilkat::Error) on failure.

top
UrlDecodeStr
pub fn url_decode_str(&self, in_str: &str) -> Result<String>

Percent-decodes in_str and interprets the resulting bytes using the platform’s legacy ANSI character encoding.

For example, in a Western Windows code page, %C9 may decode as É. UTF-8 input would encode the same character as %C3%89 and is therefore not handled correctly by this legacy assumption.

Legacy ANSI behavior: Do not use this method for modern URLs or form data unless the data is known to use the applicable ANSI code page. Use StringBuilder URL decoding with an explicit charset, normally utf-8.

Returns Err(chilkat::Error) on failure.

top
VerifyFile
pub fn verify_file(&self, charset: &str, path: &str) -> bool

Returns true when the contents of the file at path form a valid byte sequence for the charset named by charset; otherwise returns false.

Validation limitation: A successful result means only that the bytes are structurally valid for that encoding. It does not identify the encoding or confirm that the decoded text is semantically correct.
top
WriteStringToFile
pub fn write_string_to_file(&self, text_data: &str, path: &str, charset: &str) -> Result<()>

Encodes the Unicode text in text_data using the charset named by charset and writes the resulting bytes to the file at path.

Destination encoding: The charset argument is the third parameter. Select utf-8 for modern interchange unless a receiving system requires a specific legacy encoding.

Returns Ok(()) for success, Err(chilkat::Error) for failure.

top