QChar Class

The QChar class provides a 16-bit Unicode code unit. More…

List of all members, including inherited members

Public Types

Public Functions

Static Public Members

Detailed Description

A QChar holds one UTF-16 code unit. Characters outside the Basic Multilingual Plane are represented by a pair of QChar surrogates; see isHighSurrogate(), isLowSurrogate() and surrogateToUcs4(). QChar is the element type of QString.

The classification functions (isLetter(), isSpace(), isUpper() and so on) and the case conversions (toLower(), toUpper(), toCaseFolded()) use the general categories and the simple case mappings of the Unicode database (version 16). Each also has a static overload that takes a full code point as a char32_t.

QChar::isLetter(U'\U0001D400');   // true: MATHEMATICAL BOLD CAPITAL A
QChar(u'Σ').toLower();            // σ
QChar(u'٣').digitValue();         // 3

The properties used for bidirectional text and shaping come from the same database: direction(), hasMirrored() and mirroredChar(), joiningType(), script() and unicodeVersion().

See also QString and QLatin1Char.

Differences from Qt

Member Type Documentation

enum QChar::Category

The general category of a character in the Unicode database.

enum QChar::Decomposition

The kind of a character's decomposition mapping, from the tags of the Unicode Character Database.

enum QChar::Direction

The bidirectional class of a character, from the Unicode Character Database, used by the bidirectional algorithm (UAX #9).

enum QChar::JoiningType

How a character joins its neighbours in cursive scripts such as Arabic and Syriac (ArabicShaping.txt).

enum QChar::Script

The script of a character (Scripts.txt of the Unicode Character Database).

enum QChar::SpecialCharacter

Names for commonly used code points.

enum QChar::UnicodeVersion

The version of Unicode that assigned a character.

Member Function Documentation

[constexpr] QChar::QChar()

Constructs a null character (U+0000).

See also isNull().

[constexpr] QChar::QChar(char16_t c)

Constructs a character with the UTF-16 code unit c.

[constexpr] QChar::QChar(char c)

This is an overloaded function.

Constructs a character from the Latin-1 byte c. The byte is zero-extended, not interpreted as a signed value.

[constexpr] QChar::QChar(uchar c)

This is an overloaded function.

Constructs a character with the code unit c.

[constexpr] QChar::QChar(short c)

This is an overloaded function.

Constructs a character with the code unit c, reinterpreted as an unsigned 16-bit value.

[constexpr] QChar::QChar(ushort c)

This is an overloaded function.

Constructs a character with the code unit c.

[constexpr] QChar::QChar(int c)

This is an overloaded function.

Constructs a character from c, truncated to 16 bits.

[constexpr] QChar::QChar(uint c)

This is an overloaded function.

Constructs a character from c, truncated to 16 bits.

[constexpr] QChar::QChar(SpecialCharacter s)

This is an overloaded function.

Constructs a character with the code point of the special character s.

[constexpr] QChar::QChar(QLatin1Char c)

This is an overloaded function.

Constructs a character from the Latin-1 character c.

Category QChar::category() const

Returns the general category of this character.

[static] Category QChar::category(char32_t ucs4)

Returns the general category of the code point ucs4.

[constexpr] uchar QChar::cell() const

Returns the low byte of the code unit (the "cell" within its row).

See also row() and unicode().

unsigned char QChar::combiningClass() const

Returns the canonical combining class of this character, which orders combining marks during normalization; 0 for most characters.

See also QString::normalized().

[static] unsigned char QChar::combiningClass(char32_t ucs4)

This is an overloaded function.

Returns the canonical combining class of ucs4.

[static] UnicodeVersion QChar::currentUnicodeVersion()

Returns the version of the Unicode Character Database that Nt's tables were generated from.

See also unicodeVersion().

QString QChar::decomposition() const

Returns this character's decomposition mapping: the characters it decomposes into, one level deep, or an empty string if it has none.

See also decompositionTag() and QString::normalized().

[static] QString QChar::decomposition(char32_t ucs4)

This is an overloaded function.

Returns the one-level decomposition mapping of ucs4.

Decomposition QChar::decompositionTag() const

Returns the tag of this character's decomposition mapping, or NoDecomposition.

See also decomposition().

[static] Decomposition QChar::decompositionTag(char32_t ucs4)

This is an overloaded function.

Returns the tag of the decomposition mapping of ucs4.

int QChar::digitValue() const

Returns the value of this character if it is a decimal digit of any script; otherwise returns -1.

See also isDigit().

[static] int QChar::digitValue(char32_t ucs4)

This is an overloaded function.

Returns the value of ucs4 if it is a decimal digit, or -1.

Direction QChar::direction() const

Returns the bidirectional class of this character.

See also hasMirrored() and QString::isRightToLeft().

[static] Direction QChar::direction(char32_t ucs4)

This is an overloaded function.

Returns the bidirectional class of ucs4.

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

Converts the Latin-1 byte c to a QChar.

See also toLatin1().

[static, constexpr] QtPrivate::Ucs4Chars QChar::fromUcs4(char32_t c)

Returns the UTF-16 code units of the code point c: one, or a surrogate pair. The result converts to QStringView, and has size(), data(), begin() and end():

QString s = "smile ";
s += QStringView(QChar::fromUcs4(U'\U0001F600'));   // two code units

This function was introduced in 6.0.

bool QChar::hasMirrored() const

Returns true if this character is mirrored when it appears in right-to-left text, such as a parenthesis; otherwise returns false.

See also mirroredChar().

[static] bool QChar::hasMirrored(char32_t ucs4)

This is an overloaded function.

Returns true if ucs4 is mirrored in right-to-left text.

[static, constexpr] char16_t QChar::highSurrogate(char32_t ucs4)

Returns the high surrogate of the code point ucs4, which must require surrogates.

bool QChar::isDigit() const

Returns true if this is a decimal digit of any script (category Number_DecimalDigit); otherwise returns false.

See also isNumber() and digitValue().

[static] bool QChar::isDigit(char32_t ucs4)

This is an overloaded function.

Returns true if ucs4 is a decimal digit of any script.

bool QChar::isHighSurrogate() const

Returns true if this is a UTF-16 high surrogate (U+D800 to U+DBFF); otherwise returns false.

See also isLowSurrogate() and isSurrogate().

[static, constexpr] bool QChar::isHighSurrogate(char32_t ucs4)

Returns true if ucs4 is a high surrogate; otherwise returns false.

bool QChar::isLetter() const

Returns true if this is a letter (any Letter_* category); otherwise returns false.

See also isLetterOrNumber(), isUpper() and isLower().

[static] bool QChar::isLetter(char32_t ucs4)

This is an overloaded function.

Returns true if ucs4 is a letter.

bool QChar::isLetterOrNumber() const

Returns true if this is a letter or a number; otherwise returns false.

See also isLetter() and isNumber().

[static] bool QChar::isLetterOrNumber(char32_t ucs4)

This is an overloaded function.

Returns true if ucs4 is a letter or a number.

bool QChar::isLower() const

Returns true if this is a lowercase letter (Letter_Lowercase); otherwise returns false.

See also isUpper() and toLower().

[static] bool QChar::isLower(char32_t ucs4)

This is an overloaded function.

Returns true if ucs4 is a lowercase letter.

bool QChar::isLowSurrogate() const

Returns true if this is a UTF-16 low surrogate (U+DC00 to U+DFFF); otherwise returns false.

See also isHighSurrogate() and isSurrogate().

[static, constexpr] bool QChar::isLowSurrogate(char32_t ucs4)

Returns true if ucs4 is a low surrogate; otherwise returns false.

bool QChar::isMark() const

Returns true if this is a combining mark (any Mark_* category); otherwise returns false.

[static] bool QChar::isMark(char32_t ucs4)

This is an overloaded function.

Returns true if ucs4 is a combining mark.

bool QChar::isNonCharacter() const

Returns true if this is a noncharacter, such as U+FFFE; otherwise returns false.

[static, constexpr] bool QChar::isNonCharacter(char32_t ucs4)

Returns true if ucs4 is a noncharacter (U+FDD0 to U+FDEF, or a code point ending in FFFE or FFFF); otherwise returns false.

[constexpr] bool QChar::isNull() const

Returns true if this is the null character (U+0000); otherwise returns false.

bool QChar::isNumber() const

Returns true if this is a number (any Number_* category); otherwise returns false.

See also isDigit() and isLetterOrNumber().

[static] bool QChar::isNumber(char32_t ucs4)

This is an overloaded function.

Returns true if ucs4 is a number of any kind.

bool QChar::isPrint() const

Returns true if this is a printable character, that is, neither a control character nor an unassigned code point; otherwise returns false.

[static] bool QChar::isPrint(char32_t ucs4)

This is an overloaded function.

Returns true if ucs4 is printable: neither a control character nor unassigned.

bool QChar::isPunct() const

Returns true if this is a punctuation character (any Punctuation_* category); otherwise returns false.

[static] bool QChar::isPunct(char32_t ucs4)

This is an overloaded function.

Returns true if ucs4 is punctuation.

bool QChar::isSpace() const

Returns true if this is a white space character: a Separator_* character, U+0009 to U+000D or U+0085; otherwise returns false.

[static] bool QChar::isSpace(char32_t ucs4)

This is an overloaded function.

Returns true if ucs4 is white space.

bool QChar::isSurrogate() const

Returns true if this is a UTF-16 surrogate (U+D800 to U+DFFF); otherwise returns false.

See also isHighSurrogate() and isLowSurrogate().

[static, constexpr] bool QChar::isSurrogate(char32_t ucs4)

Returns true if ucs4 is a surrogate; otherwise returns false.

bool QChar::isSymbol() const

Returns true if this is a symbol (any Symbol_* category); otherwise returns false.

[static] bool QChar::isSymbol(char32_t ucs4)

This is an overloaded function.

Returns true if ucs4 is a symbol.

bool QChar::isTitleCase() const

Returns true if this is a titlecase letter (Letter_Titlecase), such as U+01C5; otherwise returns false.

See also toTitleCase().

[static] bool QChar::isTitleCase(char32_t ucs4)

This is an overloaded function.

Returns true if ucs4 is a titlecase letter.

bool QChar::isUpper() const

Returns true if this is an uppercase letter (Letter_Uppercase); otherwise returns false.

See also isLower(), isTitleCase() and toUpper().

[static] bool QChar::isUpper(char32_t ucs4)

This is an overloaded function.

Returns true if ucs4 is an uppercase letter.

JoiningType QChar::joiningType() const

Returns how this character joins its neighbours in cursive scripts.

[static] JoiningType QChar::joiningType(char32_t ucs4)

This is an overloaded function.

Returns the joining type of ucs4.

[static, constexpr] char16_t QChar::lowSurrogate(char32_t ucs4)

Returns the low surrogate of the code point ucs4, which must require surrogates.

QChar QChar::mirroredChar() const

Returns the mirror image of this character, such as ) for (, or the character itself if it has none.

See also hasMirrored().

[static] char32_t QChar::mirroredChar(char32_t ucs4)

This is an overloaded function.

Returns the mirror image of ucs4, or ucs4 itself if it has none.

[static, constexpr] bool QChar::requiresSurrogates(char32_t ucs4)

Returns true if ucs4 lies outside the Basic Multilingual Plane and so needs a surrogate pair in UTF-16; otherwise returns false.

[constexpr] uchar QChar::row() const

Returns the high byte of the code unit (the "row" of its plane).

See also cell() and unicode().

Script QChar::script() const

Returns the script this character belongs to.

[static] Script QChar::script(char32_t ucs4)

This is an overloaded function.

Returns the script of ucs4; Script_Unknown for code points that are not assigned.

[static, constexpr] char32_t QChar::surrogateToUcs4(char16_t high, char16_t low)

Returns the code point of the surrogate pair high and low.

[static, constexpr] char32_t QChar::surrogateToUcs4(QChar high, QChar low)

This is an overloaded function.

Returns the code point of the surrogate pair high and low.

QChar QChar::toCaseFolded() const

Returns the case folded equivalent of this character, which is used to compare text regardless of case.

See also toLower() and QString::toCaseFolded().

[static] char32_t QChar::toCaseFolded(char32_t ucs4)

This is an overloaded function.

Returns the simple case folding of ucs4.

[constexpr] char QChar::toLatin1() const

Returns the Latin-1 representation of this character, or '\\0' if it is outside the range 0 to 255.

See also fromLatin1() and unicode().

QChar QChar::toLower() const

Returns the lowercase equivalent of this character, or the character itself if it has none. The mapping is the simple (one-to-one) mapping of Unicode.

See also toUpper(), toCaseFolded() and QString::toLower().

[static] char32_t QChar::toLower(char32_t ucs4)

This is an overloaded function.

Returns the simple lowercase mapping of ucs4.

QChar QChar::toTitleCase() const

Returns the titlecase equivalent of this character, or the character itself if it has none.

See also toUpper() and isTitleCase().

[static] char32_t QChar::toTitleCase(char32_t ucs4)

This is an overloaded function.

Returns the simple titlecase mapping of ucs4.

QChar QChar::toUpper() const

Returns the uppercase equivalent of this character, or the character itself if it has none. The mapping is the simple (one-to-one) mapping of Unicode, so U+00DF stays as it is; QString::toUpper() uses the full mapping.

See also toLower(), toTitleCase() and QString::toUpper().

[static] char32_t QChar::toUpper(char32_t ucs4)

This is an overloaded function.

Returns the simple uppercase mapping of ucs4.

[constexpr] char16_t QChar::unicode() const

Returns the UTF-16 code unit of this character.

See also cell() and row().

[constexpr] char16_t & QChar::unicode()

This is an overloaded function.

Returns a reference to the UTF-16 code unit of this character, which can be used to modify it.

UnicodeVersion QChar::unicodeVersion() const

Returns the Unicode version that assigned this character, or Unicode_Unassigned.

See also currentUnicodeVersion().

[static] UnicodeVersion QChar::unicodeVersion(char32_t ucs4)

This is an overloaded function.

Returns the Unicode version that assigned ucs4.