Charset C# Reference Documentation

Charset

Current Version: 11.5.0
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

Chilkat.Charset obj = new Chilkat.Charset();

Properties

AltToCharset
public string AltToCharset {get; set; }

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.

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DebugLogFilePath
public string DebugLogFilePath {get; set; }

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
(C#) Example showing how to use DebugLogFilePath.(PowerShell) Example showing how to use DebugLogFilePath.
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ErrorAction
public int ErrorAction {get; set; }

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 €.
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.

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FromCharset
public string FromCharset {get; set; }

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.

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LastErrorHtml
public string LastErrorHtml {get; }

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.

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LastErrorText
public string LastErrorText {get; }

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
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LastErrorXml
public string LastErrorXml {get; }

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.

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LastInputAsHex
public string LastInputAsHex {get; }

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.

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LastInputAsQP
public string LastInputAsQP {get; }

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.

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LastMethodSuccess
public bool LastMethodSuccess {get; set; }

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.

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LastOutputAsHex
public string LastOutputAsHex {get; }

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.

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LastOutputAsQP
public string LastOutputAsQP {get; }

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.

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SaveLast
public bool SaveLast {get; set; }

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.

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ToCharset
public string ToCharset {get; set; }

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.

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VerboseLogging
public bool VerboseLogging {get; set; }

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.

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Version
public string Version {get; }

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

More Information and Examples
(C#) How to get the Chilkat version at runtime.(PowerShell) How to get the Chilkat version at runtime.
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Methods

CharsetToCodePage
public int CharsetToCodePage(string charsetName);

Returns the numeric Windows code-page identifier corresponding to charsetName. 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.
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CodePageToCharset
public string CodePageToCharset(int codePage);

Returns the charset name corresponding to the numeric code-page identifier in codePage. 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 null on failure

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ConvertData
public byte[] ConvertData(byte[] inData);

Converts the bytes in inData from FromCharset to ToCharset and returns the converted bytes.

Returns an empty byte array on failure

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ConvertFile
public bool ConvertFile(string inPath, string destPath);

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

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 true for success, false for failure.

More Information and Examples
(C#) Convert a File's Character Encoding from UTF-8 to UFT-8-BOM(PowerShell) Convert a File's Character Encoding from UTF-8 to UFT-8-BOM
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ConvertFileNoPreamble
public bool ConvertFileNoPreamble(string inPath, string destPath);

Reads the file at inPath, converts its text from FromCharset to ToCharset, and writes the converted bytes to destPath 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.
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ConvertFromUnicode
public byte[] ConvertFromUnicode(string inData);

Encodes the Unicode string in inData using ToCharset and returns the resulting bytes.

Returns an empty byte array on failure

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ConvertFromUtf16
public byte[] ConvertFromUtf16(byte[] uniData);

Converts the UTF-16 byte sequence in uniData to the character encoding specified by ToCharset and returns the resulting bytes.

Returns an empty byte array on failure

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ConvertHtml
public byte[] ConvertHtml(byte[] inData);

Converts HTML bytes in inData from FromCharset to ToCharset. The returned bytes contain the converted HTML, and Chilkat updates the HTML <meta> charset declaration to identify the destination encoding.

HTML charset declarations: Updating a <meta charset> declaration does not change HTTP response headers. When serving the converted file over HTTP, the server’s Content-Type charset must agree with the actual bytes.

Returns an empty byte array on failure

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ConvertHtmlFile
public bool ConvertHtmlFile(string inPath, string destPath);

Converts the HTML file at inPath to ToCharset and writes the result to destPath. 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 true for success, false for failure.

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ConvertToUnicode
public string ConvertToUnicode(byte[] inData);

Decodes the bytes in inData using FromCharset and returns the resulting Unicode string.

Returns null on failure

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ConvertToUtf16
public byte[] ConvertToUtf16(byte[] mbData);

Decodes the bytes in mbData using FromCharset and returns the text encoded as UTF-16 bytes.

Returns an empty byte array on failure

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EntityEncodeDec
public string EntityEncodeDec(string str);

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 null on failure

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EntityEncodeHex
public string EntityEncodeHex(string str);

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 null on failure

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GetHtmlCharset
public string GetHtmlCharset(byte[] inData);

Examines the HTML bytes in inData and returns the charset name declared by an HTML <meta> element, when present.

Metadata only: This reports the declaration found in the document. It does not verify that the bytes actually use that encoding, and it does not inspect an HTTP Content-Type header.

Returns null on failure

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GetHtmlFileCharset
public string GetHtmlFileCharset(string htmlFilePath);

Examines the HTML file at htmlFilePath 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 null on failure

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HtmlDecodeToStr
public string HtmlDecodeToStr(string inStr);

Decodes HTML named entities and numeric character references in inStr 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 null on failure

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HtmlEntityDecode
public byte[] HtmlEntityDecode(byte[] inHtml);

Decodes HTML entities and numeric character references in the byte data supplied in inHtml and returns the resulting bytes.

Operation scope: Entity decoding is not a charset conversion and does not sanitize HTML.

Returns an empty byte array on failure

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HtmlEntityDecodeFile
public bool HtmlEntityDecodeFile(string inPath, string destPath);

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

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

Returns true for success, false for failure.

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LowerCase
public string LowerCase(string inStr);

Returns the lowercase form of inStr 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 null on failure

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ReadFile
public byte[] ReadFile(string path);

Reads the entire file at path and returns its raw bytes without performing charset conversion.

Returns an empty byte array on failure

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ReadFileToString
public string ReadFileToString(string path, string charset);

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 null on failure

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SetErrorString
public void SetErrorString(string str, string charset);

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.
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UpperCase
public string UpperCase(string inStr);

Returns the uppercase form of inStr 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 null on failure

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UrlDecodeStr
public string UrlDecodeStr(string inStr);

Percent-decodes inStr 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 null on failure

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VerifyData
public bool VerifyData(string charset, byte[] inData);

Returns true when the bytes in inData form a valid sequence for the charset named by charset; otherwise returns false.

What validation means: This checks encoding validity only. It does not prove that the selected charset is the intended one. For many single-byte encodings, every possible byte value is valid.
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VerifyFile
public bool VerifyFile(string charset, string path);

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.
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WriteFile
public bool WriteFile(string path, byte[] byteData);

Writes all bytes from byteData to the file at path without performing charset conversion.

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WriteStringToFile
public bool WriteStringToFile(string textData, string path, string charset);

Encodes the Unicode text in textData 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 true for success, false for failure.

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