Contents

• Public Types
• Public Functions
• Static Public Members
• Related Non-Members
• Detailed Description

Detailed Description

TheQChar class provides a 16-bit Unicode character.

In Qt, Unicode characters are 16-bit entities without any markup or structure. This class represents such an entity. It is lightweight, so it can be used everywhere. Most compilers treat it like aunsigned short.

QChar provides a full complement of testing/classification functions, converting to and from other formats, converting from composed to decomposed Unicode, and trying to compare and case-convert if you ask it to.

The classification functions include functions like those in the standard C++ header <cctype> (formerly <ctype.h>), but operating on the full range of Unicode characters. They all return true if the character is a certain type of character; otherwise they return false. These classification functions areisNull() (returns true if the character is '\0'),isPrint() (true if the character is any sort of printable character, including whitespace),isPunct() (any sort of punctation),isMark() (Unicode Mark),isLetter() (a letter),isNumber() (any sort of numeric character, not just 0-9),isLetterOrNumber(), andisDigit() (decimal digits). All of these are wrappers aroundcategory() which return the Unicode-defined category of each character.

QChar also providesdirection(), which indicates the "natural" writing direction of this character. Thejoining() function indicates how the character joins with its neighbors (needed mostly for Arabic) and finallyhasMirrored(), which indicates whether the character needs to be mirrored when it is printed in its "unnatural" writing direction.

Composed Unicode characters (like å) can be converted to decomposed Unicode ("a" followed by "ring above") by usingdecomposition().

In Unicode, comparison is not necessarily possible and case conversion is very difficult at best. Unicode, covering the "entire" world, also includes most of the world's case and sorting problems. operator==() and friends will do comparison based purely on the numeric Unicode value (code point) of the characters, andtoUpper() andtoLower() will do case changes when the character has a well-defined uppercase/lowercase equivalent. For locale-dependent comparisons, useQString::localeAwareCompare().

The conversion functions includeunicode() (to a scalar),toLatin1() (to scalar, but converts all non-Latin-1 characters to 0),row() (gives the Unicode row),cell() (gives the Unicode cell),digitValue() (gives the integer value of any of the numerous digit characters), and a host of constructors.

QChar provides constructors and cast operators that make it easy to convert to and from traditional 8-bitchars. If you definedQT_NO_CAST_FROM_ASCII andQT_NO_CAST_TO_ASCII, as explained in theQString documentation, you will need to explicitly callfromAscii() orfromLatin1(), or useQLatin1Char, to construct aQChar from an 8-bitchar, and you will need to calltoAscii() ortoLatin1() to get the 8-bit value back.

Member Type Documentation

enum QChar::Category

This enum maps the Unicode character categories.

The following characters are normative in Unicode:

The following categories are informative in Unicode:

See alsocategory().

enum QChar::Decomposition

This enum type defines the Unicode decomposition attributes. See theUnicode Standard for a description of the values.

See alsodecomposition().

enum QChar::Direction

This enum type defines the Unicode direction attributes. See theUnicode Standard for a description of the values.

In order to conform to C/C++ naming conventions "Dir" is prepended to the codes used in the Unicode Standard.

See alsodirection().

enum QChar::Joining

This enum type defines the Unicode joining attributes. See theUnicode Standard for a description of the values.

See alsojoining().

enum QChar::SpecialCharacter

enum QChar::UnicodeVersion

Specifies which version of theUnicode standard introduced a certain character.

See alsounicodeVersion().

Member Function Documentation

QChar::QChar()

Constructs a nullQChar ('\0').

See alsoisNull().

QChar::QChar(char ch)

Constructs aQChar corresponding to ASCII/Latin-1 characterch.

QChar::QChar(uchar ch)

Constructs aQChar corresponding to ASCII/Latin-1 characterch.

QChar::QChar(QLatin1Char ch)

Constructs aQChar corresponding to ASCII/Latin-1 characterch.

QChar::QChar(uchar cell,uchar row)

Constructs aQChar for Unicode cellcell in rowrow.

See alsocell() androw().

QChar::QChar(ushort code)

Constructs aQChar for the character with Unicode code pointcode.

QChar::QChar(short code)

Constructs aQChar for the character with Unicode code pointcode.

QChar::QChar(uint code)

Constructs aQChar for the character with Unicode code pointcode.

QChar::QChar(int code)

Constructs aQChar for the character with Unicode code pointcode.

QChar::QChar(SpecialCharacter ch)

Constructs aQChar for the predefined character valuech.

Category QChar::category() const

Returns the character's category.

[static]Category QChar::category(uint ucs4)

This is an overloaded function.

Returns the category of the UCS-4-encoded character specified byucs4.

This function was introduced in Qt 4.3.

[static]Category QChar::category(ushort ucs2)

This is an overloaded function.

Returns the category of the UCS-2-encoded character specified byucs2.

uchar QChar::cell() const

Returns the cell (least significant byte) of the Unicode character.

See alsorow().

unsignedchar QChar::combiningClass() const

Returns the combining class for the character as defined in the Unicode standard. This is mainly useful as a positioning hint for marks attached to a base character.

The Qt text rendering engine uses this information to correctly position non-spacing marks around a base character.

[static]unsignedchar QChar::combiningClass(uint ucs4)

This is an overloaded function.

Returns the combining class for the UCS-4-encoded character specified byucs4, as defined in the Unicode standard.

[static]unsignedchar QChar::combiningClass(ushort ucs2)

This is an overloaded function.

Returns the combining class for the UCS-2-encoded character specified byucs2, as defined in the Unicode standard.

[static]UnicodeVersion QChar::currentUnicodeVersion()

Returns the most recent supported Unicode version.

This function was introduced in Qt 4.8.

QString QChar::decomposition() const

Decomposes a character into its parts. Returns an empty string if no decomposition exists.

[static]QString QChar::decomposition(uint ucs4)

This is an overloaded function.

Decomposes the UCS-4-encoded character specified byucs4 into its constituent parts. Returns an empty string if no decomposition exists.

Decomposition QChar::decompositionTag() const

Returns the tag defining the composition of the character. ReturnsQChar::Single if no decomposition exists.

[static]Decomposition QChar::decompositionTag(uint ucs4)

This is an overloaded function.

Returns the tag defining the composition of the UCS-4-encoded character specified byucs4. ReturnsQChar::Single if no decomposition exists.

int QChar::digitValue() const

Returns the numeric value of the digit, or -1 if the character is not a digit.

[static]int QChar::digitValue(ushort ucs2)

This is an overloaded function.

Returns the numeric value of the digit, specified by the UCS-2-encoded character,ucs2, or -1 if the character is not a digit.

[static]int QChar::digitValue(uint ucs4)

This is an overloaded function.

Returns the numeric value of the digit specified by the UCS-4-encoded character,ucs4, or -1 if the character is not a digit.

Direction QChar::direction() const

Returns the character's direction.

[static]Direction QChar::direction(uint ucs4)

This is an overloaded function.

Returns the direction of the UCS-4-encoded character specified byucs4.

[static]Direction QChar::direction(ushort ucs2)

This is an overloaded function.

Returns the direction of the UCS-2-encoded character specified byucs2.

[static]QChar QChar::fromAscii(char c)

Converts the ASCII characterc to its equivalentQChar. This is mainly useful for non-internationalized software.

An alternative is to useQLatin1Char.

See alsofromLatin1(),unicode(), andQTextCodec::codecForCStrings().

[static]QChar QChar::fromLatin1(char c)

Converts the Latin-1 characterc to its equivalentQChar. This is mainly useful for non-internationalized software.

See alsofromAscii(),unicode(), andQTextCodec::codecForCStrings().

bool QChar::hasMirrored() const

Returns true if the character should be reversed if the text direction is reversed; otherwise returns false.

Same as (ch.mirroredChar() != ch).

See alsomirroredChar().

[static]ushort QChar::highSurrogate(uint ucs4)

Returns the high surrogate value of a ucs4 code point. The returned result is undefined ifucs4 is smaller than 0x10000.

bool QChar::isDigit() const

Returns true if the character is a decimal digit (Number_DecimalDigit); otherwise returns false.

bool QChar::isHighSurrogate() const

Returns true if theQChar is the high part of a utf16 surrogate (ie. if its code point is between 0xd800 and 0xdbff, inclusive).

[static]bool QChar::isHighSurrogate(uint ucs4)

Returns true if the UCS-4-encoded character specified byucs4 is the high part of a utf16 surrogate (ie. if its code point is between 0xd800 and 0xdbff, inclusive).

This function was introduced in Qt 4.7.

bool QChar::isLetter() const

Returns true if the character is a letter (Letter_* categories); otherwise returns false.

bool QChar::isLetterOrNumber() const

Returns true if the character is a letter or number (Letter_* orNumber_* categories); otherwise returns false.

bool QChar::isLowSurrogate() const

Returns true if theQChar is the low part of a utf16 surrogate (ie. if its code point is between 0xdc00 and 0xdfff, inclusive).

[static]bool QChar::isLowSurrogate(uint ucs4)

Returns true if the UCS-4-encoded character specified byucs4 is the low part of a utf16 surrogate (ie. if its code point is between 0xdc00 and 0xdfff, inclusive).

This function was introduced in Qt 4.7.

bool QChar::isLower() const

Returns true if the character is a lowercase letter, i.e.category() isLetter_Lowercase.

See alsoisUpper(),toLower(), andtoUpper().

bool QChar::isMark() const

Returns true if the character is a mark (Mark_* categories); otherwise returns false.

SeeQChar::Category for more information regarding marks.

bool QChar::isNull() const

Returns true if the character is the Unicode character 0x0000 ('\0'); otherwise returns false.

bool QChar::isNumber() const

Returns true if the character is a number (Number_* categories, not just 0-9); otherwise returns false.

See alsoisDigit().

bool QChar::isPrint() const

Returns true if the character is a printable character; otherwise returns false. This is any character not of category Cc or Cn.

Note that this gives no indication of whether the character is available in a particular font.

bool QChar::isPunct() const

Returns true if the character is a punctuation mark (Punctuation_* categories); otherwise returns false.

bool QChar::isSpace() const

Returns true if the character is a separator character (Separator_* categories); otherwise returns false.

bool QChar::isSymbol() const

Returns true if the character is a symbol (Symbol_* categories); otherwise returns false.

bool QChar::isTitleCase() const

Returns true if the character is a titlecase letter, i.e.category() isLetter_Titlecase.

This function was introduced in Qt 4.3.

See alsoisLower(),toUpper(),toLower(), andtoTitleCase().

bool QChar::isUpper() const

Returns true if the character is an uppercase letter, i.e.category() isLetter_Uppercase.

See alsoisLower(),toUpper(), andtoLower().

Joining QChar::joining() const

Returns information about the joining properties of the character (needed for certain languages such as Arabic).

[static]Joining QChar::joining(uint ucs4)

This is an overloaded function.

Returns information about the joining properties of the UCS-4-encoded character specified byucs4 (needed for certain languages such as Arabic).

[static]Joining QChar::joining(ushort ucs2)

This is an overloaded function.

Returns information about the joining properties of the UCS-2-encoded character specified byucs2 (needed for certain languages such as Arabic).

[static]ushort QChar::lowSurrogate(uint ucs4)

Returns the low surrogate value of a ucs4 code point. The returned result is undefined ifucs4 is smaller than 0x10000.

QChar QChar::mirroredChar() const

Returns the mirrored character if this character is a mirrored character; otherwise returns the character itself.

See alsohasMirrored().

[static]uint QChar::mirroredChar(uint ucs4)

This is an overloaded function.

Returns the mirrored character if the UCS-4-encoded character specified byucs4 is a mirrored character; otherwise returns the character itself.

See alsohasMirrored().

[static]ushort QChar::mirroredChar(ushort ucs2)

This is an overloaded function.

Returns the mirrored character if the UCS-2-encoded character specified byucs2 is a mirrored character; otherwise returns the character itself.

See alsohasMirrored().

[static]bool QChar::requiresSurrogates(uint ucs4)

Returns true if the UCS-4-encoded character specified byucs4 can be split into the high and low parts of a utf16 surrogate (ie. if its code point is greater than or equals to 0x10000).

This function was introduced in Qt 4.7.

uchar QChar::row() const

Returns the row (most significant byte) of the Unicode character.

See alsocell().

[static]uint QChar::surrogateToUcs4(ushort high,ushort low)

Converts a UTF16 surrogate pair with the givenhigh andlow values to its UCS-4 code point.

[static]uint QChar::surrogateToUcs4(QChar high,QChar low)

Converts a utf16 surrogate pair (high,low) to its ucs4 code point.

char QChar::toAscii() const

Returns the character value of theQChar obtained using the current codec used to read C strings, or 0 if the character is not representable using this codec. The default codec handles Latin-1 encoded text, but this can be changed to assist developers writing source code using other encodings.

The main purpose of this function is to preserve ASCII characters used in C strings. This is mainly useful for developers of non-internationalized software.

See alsotoLatin1(),unicode(), andQTextCodec::codecForCStrings().

QChar QChar::toCaseFolded() const

Returns the case folded equivalent of the character. For most Unicode characters this is the same as toLowerCase().

[static]uint QChar::toCaseFolded(uint ucs4)

This is an overloaded function.

Returns the case folded equivalent of the UCS-4-encoded character specified byucs4. For most Unicode characters this is the same as toLowerCase().

[static]ushort QChar::toCaseFolded(ushort ucs2)

This is an overloaded function.

Returns the case folded equivalent of the UCS-2-encoded character specified byucs2. For most Unicode characters this is the same as toLowerCase().

char QChar::toLatin1() const

Returns the Latin-1 character equivalent to theQChar, or 0. This is mainly useful for non-internationalized software.

See alsotoAscii(),unicode(), andQTextCodec::codecForCStrings().

QChar QChar::toLower() const

Returns the lowercase equivalent if the character is uppercase or titlecase; otherwise returns the character itself.

[static]uint QChar::toLower(uint ucs4)

This is an overloaded function.

Returns the lowercase equivalent of the UCS-4-encoded character specified byucs4 if the character is uppercase or titlecase; otherwise returns the character itself.

[static]ushort QChar::toLower(ushort ucs2)

This is an overloaded function.

Returns the lowercase equivalent of the UCS-2-encoded character specified byucs2 if the character is uppercase or titlecase; otherwise returns the character itself.

QChar QChar::toTitleCase() const

Returns the title case equivalent if the character is lowercase or uppercase; otherwise returns the character itself.

[static]uint QChar::toTitleCase(uint ucs4)

This is an overloaded function.

Returns the title case equivalent of the UCS-4-encoded character specified byucs4 if the character is lowercase or uppercase; otherwise returns the character itself.

[static]ushort QChar::toTitleCase(ushort ucs2)

This is an overloaded function.

Returns the title case equivalent of the UCS-2-encoded character specified byucs2 if the character is lowercase or uppercase; otherwise returns the character itself.

QChar QChar::toUpper() const

Returns the uppercase equivalent if the character is lowercase or titlecase; otherwise returns the character itself.

[static]uint QChar::toUpper(uint ucs4)

This is an overloaded function.

Returns the uppercase equivalent of the UCS-4-encoded character specified byucs4 if the character is lowercase or titlecase; otherwise returns the character itself.

[static]ushort QChar::toUpper(ushort ucs2)

This is an overloaded function.

Returns the uppercase equivalent of the UCS-2-encoded character specified byucs2 if the character is lowercase or titlecase; otherwise returns the character itself.

ushort & QChar::unicode()

Returns a reference to the numeric Unicode value of theQChar.

ushort QChar::unicode() const

This is an overloaded function.

UnicodeVersion QChar::unicodeVersion() const

Returns the Unicode version that introduced this character.

[static]UnicodeVersion QChar::unicodeVersion(uint ucs4)

This is an overloaded function.

Returns the Unicode version that introduced the character specified in its UCS-4-encoded form asucs4.

[static]UnicodeVersion QChar::unicodeVersion(ushort ucs2)

This is an overloaded function.

Returns the Unicode version that introduced the character specified in its UCS-2-encoded form asucs2.

Related Non-Members

booloperator!=(QChar c1,QChar c2)

Returns true ifc1 andc2 are not the same Unicode character; otherwise returns false.

booloperator<(QChar c1,QChar c2)

Returns true if the numeric Unicode value ofc1 is less than that ofc2; otherwise returns false.

QDataStream &operator<<(QDataStream & out, constQChar & chr)

Writes the charchr to the streamout.

See alsoSerializing Qt Data Types.

booloperator<=(QChar c1,QChar c2)

Returns true if the numeric Unicode value ofc1 is less than or equal to that ofc2; otherwise returns false.

booloperator==(QChar c1,QChar c2)

Returns true ifc1 andc2 are the same Unicode character; otherwise returns false.

booloperator>(QChar c1,QChar c2)

Returns true if the numeric Unicode value ofc1 is greater than that ofc2; otherwise returns false.

booloperator>=(QChar c1,QChar c2)

Returns true if the numeric Unicode value ofc1 is greater than or equal to that ofc2; otherwise returns false.

QDataStream &operator>>(QDataStream & in,QChar & chr)

Reads a char from the streamin into charchr.

See alsoSerializing Qt Data Types.