Struct qt_core::QChar

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#[repr(C)]
pub struct QChar { /* private fields */ }

Expand description

The QChar class provides a 16-bit Unicode character.

C++ class: QChar.

C++ documentation:

The QChar 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 an unsigned 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, not just for the ASCII range. They all return true if the character is a certain type of character; otherwise they return false. These classification functions are isNull() (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(), and isDigit() (decimal digits). All of these are wrappers around category() which return the Unicode-defined category of each character. Some of these also calculate the derived properties (for example isSpace() returns true if the character is of category Separator_* or an exceptional code point from Other_Control category).

QChar also provides direction(), which indicates the "natural" writing direction of this character. The joiningType() function indicates how the character joins with it's neighbors (needed mostly for Arabic or Syriac) and finally hasMirrored(), which indicates whether the character needs to be mirrored when it is printed in it's "unnatural" writing direction.

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

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, and toUpper() and toLower() will do case changes when the character has a well-defined uppercase/lowercase equivalent. For locale-dependent comparisons, use QString::localeAwareCompare().

The conversion functions include unicode() (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-bit chars. If you defined QT_NO_CAST_FROM_ASCII and QT_NO_CAST_TO_ASCII, as explained in the QString documentation, you will need to explicitly call fromLatin1(), or use QLatin1Char, to construct a QChar from an 8-bit char, and you will need to call toLatin1() to get the 8-bit value back.

For more information see "About the Unicode Character Database".

Implementations§

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impl QChar

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pub unsafe fn category_0a(&self) -> Category

Returns the character's category.

Calls C++ function: QChar::Category QChar::category() const.

C++ documentation:

Returns the character’s category.

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pub unsafe fn category_1a(ucs4: c_uint) -> Category

This is an overloaded function.

Calls C++ function: static QChar::Category QChar::category(unsigned int ucs4).

C++ documentation:

This is an overloaded function.

Returns the category of the UCS-4-encoded character specified by ucs4.

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pub unsafe fn cell(&self) -> c_uchar

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

Calls C++ function: unsigned char QChar::cell() const.

C++ documentation:

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

See also row().

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pub unsafe fn combining_class_0a(&self) -> c_uchar

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.

Calls C++ function: unsigned char QChar::combiningClass() const.

C++ documentation:

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.

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pub unsafe fn combining_class_1a(ucs4: c_uint) -> c_uchar

This is an overloaded function.

Calls C++ function: static unsigned char QChar::combiningClass(unsigned int ucs4).

C++ documentation:

This is an overloaded function.

Returns the combining class for the UCS-4-encoded character specified by ucs4, as defined in the Unicode standard.

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pub unsafe fn copy_from(&self, other: impl CastInto<Ref<QChar>>) -> Ref<QChar>

The QChar class provides a 16-bit Unicode character.

Calls C++ function: QChar& QChar::operator=(const QChar& other).