QLocale Class Reference
[QtCore module]

Detailed Description

The QLocale class converts between numbers and their string representations in various languages.

QLocale is initialized with a language/country pair in its constructor and offers number-to-string and string-to-number conversion functions similar to those in QString.

Example:

 QLocale egyptian(QLocale::Arabic, QLocale::Egypt);
 QString s1 = egyptian.toString(1.571429E+07, 'e');
 QString s2 = egyptian.toString(10);

 double d = egyptian.toDouble(s1);
 int i = egyptian.toInt(s2);

QLocale supports the concept of a default locale, which is determined from the system's locale settings at application startup. The default locale can be changed by calling the static member setDefault(). Setting the default locale has the following effects:

• If a QLocale object is constructed with the default constructor, it will use the default locale's settings.
• QString::toInt(), QString::toDouble(), etc., interpret the string according to the default locale. If this fails, it falls back on the "C" locale.
• QString::arg() uses the default locale to format a number when its position specifier in the format string contains an 'L', e.g. "%L1".

The following example illustrates how to use QLocale directly:

 QLocale::setDefault(QLocale(QLocale::Hebrew, QLocale::Israel));
 QLocale hebrew; // Constructs a default QLocale
 QString s1 = hebrew.toString(15714.3, 'e');

 bool ok;
 double d;

 QLocale::setDefault(QLocale::C);
 d = QString("1234,56").toDouble(&ok);   // ok == false
 d = QString("1234.56").toDouble(&ok);   // ok == true, d == 1234.56

 QLocale::setDefault(QLocale::German);
 d = QString("1234,56").toDouble(&ok);   // ok == true, d == 1234.56
 d = QString("1234.56").toDouble(&ok);   // ok == true, d == 1234.56

 QLocale::setDefault(QLocale(QLocale::English, QLocale::UnitedStates));
 str = QString("%1 %L2 %L3")
       .arg(12345).arg(12345).arg(12345, 0, 16);
 // str == "12345 12,345 3039"

When a language/country pair is specified in the constructor, one of three things can happen:

• If the language/country pair is found in the database, it is used.
• If the language is found but the country is not, or if the country is AnyCountry, the language is used with the most appropriate available country (for example, Germany for German),
• If neither the language nor the country are found, QLocale defaults to the default locale (see setDefault()).

The "C" locale is identical to English/UnitedStates.

Use language() and country() to determine the actual language and country values used.

An alternative method for constructing a QLocale object is by specifying the locale name.

 QLocale korean("ko");
 QLocale swiss("de_CH");

This constructor converts the locale name to a language/country pair; it does not use the system locale database.

The double-to-string and string-to-double conversion functions are covered by the following licenses:

See also QString::arg(), QString::toInt(), and QString::toDouble().

Member Type Documentation

enum QLocale::Country

This enumerated type is used to specify a country.

See also country().

enum QLocale::FormatType

This enum describes the types of format that can be used when converting QDate and QTime objects to strings.

enum QLocale::Language

This enumerated type is used to specify a language.

See also language().

enum QLocale::MeasurementSystem

This enum defines which units are used for measurement.

This enum was introduced in Qt 4.4.

enum QLocale::NumberOption
flags QLocale::NumberOptions

This enum defines a set of options for number-to-string and string-to-number conversions. They can be retrieved with numberOptions() and set with setNumberOptions().

The NumberOptions type is a typedef for QFlags<NumberOption>. It stores an OR combination of NumberOption values.

See also setNumberOptions() and numberOptions().

Member Function Documentation

QLocale::QLocale ()

Constructs a QLocale object initialized with the default locale. If no default locale was set using setDefaultLocale(), this locale will be the same as the one returned by system().

See also setDefault().

QLocale::QLocale ( const QString & name )

Constructs a QLocale object with the specified name, which has the format "language[_country][.codeset][@modifier]" or "C", where:

• language is a lowercase, two-letter, ISO 639 language code,
• territory is an uppercase, two-letter, ISO 3166 country code,
• and codeset and modifier are ignored.

If the string violates the locale format, or language is not a valid ISO 369 code, the "C" locale is used instead. If country is not present, or is not a valid ISO 3166 code, the most appropriate country is chosen for the specified language.

The language and country codes are converted to their respective Language and Country enums. After this conversion is performed the constructor behaves exactly like QLocale(Country, Language).

This constructor is much slower than QLocale(Country, Language).

See also name().

QLocale::QLocale ( Language language, Country country = AnyCountry )

Constructs a QLocale object with the specified language and country.

• If the language/country pair is found in the database, it is used.
• If the language is found but the country is not, or if the country is AnyCountry, the language is used with the most appropriate available country (for example, Germany for German),
• If neither the language nor the country are found, QLocale defaults to the default locale (see setDefault()).

The language and country that are actually used can be queried using language() and country().

See also setDefault(), language(), and country().

QLocale::QLocale ( const QLocale & other )

Constructs a QLocale object as a copy of other.

QLocale QLocale::c ()   [static]

Returns a QLocale object initialized to the "C" locale.

See also system().

QList<Country> QLocale::countriesForLanguage ( Language language )   [static]

Returns the list of countries that have entires for language in Qt's locale database. If the result is an empty list, then language is not represented in Qt's locale database.

This function was introduced in Qt 4.3.

Country QLocale::country () const

Returns the country of this locale.

See also language(), countryToString(), and name().

QString QLocale::countryToString ( Country country )   [static]

Returns a QString containing the name of country.

See also country() and name().

QString QLocale::dateFormat ( FormatType format = LongFormat ) const

Returns the date format used for the current locale.

If format is ShortFormat the format will be a short version. Otherwise it uses a longer version.

This function was introduced in Qt 4.1.

See also QDate::toString() and QDate::fromString().

QString QLocale::dateTimeFormat ( FormatType format = LongFormat ) const

Returns the date time format used for the current locale.

If format is ShortFormat the format will be a short version. Otherwise it uses a longer version.

This function was introduced in Qt 4.4.

See also QDateTime::toString() and QDateTime::fromString().

QString QLocale::dayName ( int day, FormatType type = LongFormat ) const

Returns the localized name of day, in the format specified by type.

This function was introduced in Qt 4.2.

See also monthName().

QChar QLocale::decimalPoint () const

Returns the decimal point character of this locale.

This function was introduced in Qt 4.1.

QChar QLocale::exponential () const

Returns the exponential character of this locale.

This function was introduced in Qt 4.1.

QChar QLocale::groupSeparator () const

Returns the group separator character of this locale.

This function was introduced in Qt 4.1.

Language QLocale::language () const

Returns the language of this locale.

See also country(), languageToString(), and name().

QString QLocale::languageToString ( Language language )   [static]

Returns a QString containing the name of language.

See also countryToString() and name().

MeasurementSystem QLocale::measurementSystem () const

Returns the measurement system for the locale.

This function was introduced in Qt 4.4.

QString QLocale::monthName ( int month, FormatType type = LongFormat ) const

Returns the localized name of month, in the format specified by type.

This function was introduced in Qt 4.2.

See also dayName().

QString QLocale::name () const

Returns the language and country of this locale as a string of the form "language_country", where language is a lowercase, two-letter ISO 639 language code, and country is an uppercase, two-letter ISO 3166 country code.

See also language() and country().

QChar QLocale::negativeSign () const

Returns the negative sign character of this locale.

This function was introduced in Qt 4.1.

NumberOptions QLocale::numberOptions () const

Returns the options related to number conversions for this QLocale instance.

By default, no options are set for the standard locales.

This function was introduced in Qt 4.2.

See also setNumberOptions().

QChar QLocale::percent () const

Returns the percent character of this locale.

This function was introduced in Qt 4.1.

void QLocale::setDefault ( const QLocale & locale )   [static]

Sets the global default locale to locale. These values are used when a QLocale object is constructed with no arguments. If this function is not called, the system's locale is used.

Warning: In a multithreaded application, the default locale should be set at application startup, before any non-GUI threads are created.

Warning: This function is not reentrant.

See also system() and c().

void QLocale::setNumberOptions ( NumberOptions options )

Sets the options related to number conversions for this QLocale instance.

This function was introduced in Qt 4.2.

See also numberOptions().

QLocale QLocale::system ()   [static]

Returns a QLocale object initialized to the system locale.

On Windows and Mac, this locale will use the decimal/grouping characters and date/time formats specified in the system configuration panel.

See also QTextCodec::locale() and c().

QString QLocale::timeFormat ( FormatType format = LongFormat ) const

Returns the time format used for the current locale.

If format is ShortFormat the format will be a short version. Otherwise it uses a longer version.

This function was introduced in Qt 4.1.

See also QTime::toString() and QTime::fromString().

QDate QLocale::toDate ( const QString & string, FormatType format = LongFormat ) const

Parses the date string given in string and returns the date. The format of the date string is chosen according to the format parameter (see dateFormat()).

If the date could not be parsed, returns an invalid date.

This function was introduced in Qt 4.4.

See also dateFormat(), toTime(), toDateTime(), and QDate::fromString().

QDate QLocale::toDate ( const QString & string, const QString & format ) const

This is an overloaded member function, provided for convenience.

Parses the date string given in string and returns the date. See QDate::fromString() for information on the expressions that can be used with this function.

This function searches month names and the names of the days of the week in the current locale.

If the date could not be parsed, returns an invalid date.

This function was introduced in Qt 4.4.

See also dateFormat(), toTime(), toDateTime(), and QDate::fromString().

QDateTime QLocale::toDateTime ( const QString & string, FormatType format = LongFormat ) const

Parses the date/time string given in string and returns the time. The format of the date/time string is chosen according to the format parameter (see dateTimeFormat()).

If the string could not be parsed, returns an invalid QDateTime.

This function was introduced in Qt 4.4.

See also dateTimeFormat(), toTime(), toDate(), and QDateTime::fromString().

QDateTime QLocale::toDateTime ( const QString & string, const QString & format ) const

This is an overloaded member function, provided for convenience.

Parses the date/time string given in string and returns the time. See QDateTime::fromString() for information on the expressions that can be used with this function.

Note: The month and day names used must be given in the user's local language.

If the string could not be parsed, returns an invalid QDateTime.

This function was introduced in Qt 4.4.

See also dateTimeFormat(), toTime(), toDate(), and QDateTime::fromString().

double QLocale::toDouble ( const QString & s, bool * ok = 0 ) const

Returns the double represented by the localized string s, or 0.0 if the conversion failed.

If ok is not 0, reports failure by setting *ok to false and success by setting *ok to true.

Unlike QString::toDouble(), this function does not fall back to the "C" locale if the string cannot be interpreted in this locale.

 bool ok;
 double d;

 QLocale c(QLocale::C);
 d = c.toDouble( "1234.56", &ok );  // ok == true, d == 1234.56
 d = c.toDouble( "1,234.56", &ok ); // ok == true, d == 1234.56
 d = c.toDouble( "1234,56", &ok );  // ok == false

 QLocale german(QLocale::German);
 d = german.toDouble( "1234,56", &ok );  // ok == true, d == 1234.56
 d = german.toDouble( "1.234,56", &ok ); // ok == true, d == 1234.56
 d = german.toDouble( "1234.56", &ok );  // ok == false

 d = german.toDouble( "1.234", &ok );    // ok == true, d == 1234.0

Notice that the last conversion returns 1234.0, because '.' is the thousands group separator in the German locale.

This function ignores leading and trailing whitespace.

See also toFloat(), toInt(), and toString().

float QLocale::toFloat ( const QString & s, bool * ok = 0 ) const

Returns the float represented by the localized string s, or 0.0 if the conversion failed.

If ok is not 0, reports failure by setting *ok to false and success by setting *ok to true.

This function ignores leading and trailing whitespace.

See also toDouble(), toInt(), and toString().

int QLocale::toInt ( const QString & s, bool * ok = 0, int base = 0 ) const

Returns the int represented by the localized string s, using base base. If base is 0 the base is determined automatically using the following rules: If the string begins with "0x", it is assumed to be hexadecimal; if it begins with "0", it is assumed to be octal; otherwise it is assumed to be decimal.

If the conversion fails the function returns 0.

If ok is not 0, failure is reported by setting *ok to false, and success by setting *ok to true.

This function ignores leading and trailing whitespace.

See also toUInt() and toString().

qlonglong QLocale::toLongLong ( const QString & s, bool * ok = 0, int base = 0 ) const

Returns the long long int represented by the localized string s, using base base. If base is 0 the base is determined automatically using the following rules: If the string begins with "0x", it is assumed to be hexadecimal; if it begins with "0", it is assumed to be octal; otherwise it is assumed to be decimal.

If the conversion fails the function returns 0.

If ok is not 0, failure is reported by setting *ok to false, and success by setting *ok to true.

This function ignores leading and trailing whitespace.

See also toInt(), toULongLong(), toDouble(), and toString().

short QLocale::toShort ( const QString & s, bool * ok = 0, int base = 0 ) const

Returns the short int represented by the localized string s, using base base. If base is 0 the base is determined automatically using the following rules: If the string begins with "0x", it is assumed to be hexadecimal; if it begins with "0", it is assumed to be octal; otherwise it is assumed to be decimal.

If the conversion fails the function returns 0.

If ok is not 0, failure is reported by setting *ok to false, and success by setting *ok to true.

This function ignores leading and trailing whitespace.

See also toUShort() and toString().

QString QLocale::toString ( qlonglong i ) const

Returns a localized string representation of i.

See also toLongLong().

QString QLocale::toString ( const QDate & date, const QString & format ) const

This is an overloaded member function, provided for convenience.

Returns a localized string representation of the given date in the specified format. If format is an empty string, an empty string is returned.

QString QLocale::toString ( const QDate & date, FormatType format = LongFormat ) const

This is an overloaded member function, provided for convenience.

Returns a localized string representation of the given date according to the specified format.

QString QLocale::toString ( const QTime & time, const QString & format ) const

This is an overloaded member function, provided for convenience.

Returns a localized string representation of the given time according to the specified format. If format is an empty string, an empty string is returned.

QString QLocale::toString ( const QTime & time, FormatType format = LongFormat ) const

This is an overloaded member function, provided for convenience.

Returns a localized string representation of the given time in the specified format.

QString QLocale::toString ( const QDateTime & dateTime, FormatType format = LongFormat ) const

This is an overloaded member function, provided for convenience.

Returns a localized string representation of the given dateTime according to the specified format.

This function was introduced in Qt 4.4.

QString QLocale::toString ( const QDateTime & dateTime, const QString & format ) const

This is an overloaded member function, provided for convenience.

Returns a localized string representation of the given dateTime according to the specified format. If format is an empty string, an empty string is returned.

This function was introduced in Qt 4.4.

QString QLocale::toString ( qulonglong i ) const

This is an overloaded member function, provided for convenience.

See also toULongLong().

QString QLocale::toString ( double i, char f = 'g', int prec = 6 ) const

This is an overloaded member function, provided for convenience.

f and prec have the same meaning as in QString::number(double, char, int).

See also toDouble().

QString QLocale::toString ( short i ) const

This is an overloaded member function, provided for convenience.

See also toShort().

QString QLocale::toString ( ushort i ) const

This is an overloaded member function, provided for convenience.

See also toUShort().

QString QLocale::toString ( int i ) const

This is an overloaded member function, provided for convenience.

See also toInt().

QString QLocale::toString ( uint i ) const

This is an overloaded member function, provided for convenience.

See also toUInt().

QString QLocale::toString ( float i, char f = 'g', int prec = 6 ) const

This is an overloaded member function, provided for convenience.

f and prec have the same meaning as in QString::number(double, char, int).

See also toDouble().

QTime QLocale::toTime ( const QString & string, FormatType format = LongFormat ) const

Parses the time string given in string and returns the time. The format of the time string is chosen according to the format parameter (see timeFormat()).

If the time could not be parsed, returns an invalid time.

This function was introduced in Qt 4.4.

See also timeFormat(), toDate(), toDateTime(), and QTime::fromString().

QTime QLocale::toTime ( const QString & string, const QString & format ) const

This is an overloaded member function, provided for convenience.

Parses the time string given in string and returns the time. See QTime::fromString() for information on what is a valid format string.

If the time could not be parsed, returns an invalid time.

This function was introduced in Qt 4.4.

See also timeFormat(), toDate(), toDateTime(), and QTime::fromString().

uint QLocale::toUInt ( const QString & s, bool * ok = 0, int base = 0 ) const

Returns the unsigned int represented by the localized string s, using base base. If base is 0 the base is determined automatically using the following rules: If the string begins with "0x", it is assumed to be hexadecimal; if it begins with "0", it is assumed to be octal; otherwise it is assumed to be decimal.

If the conversion fails the function returns 0.

If ok is not 0, failure is reported by setting *ok to false, and success by setting *ok to true.

This function ignores leading and trailing whitespace.

See also toInt() and toString().

qlonglong QLocale::toULongLong ( const QString & s, bool * ok = 0, int base = 0 ) const

Returns the unsigned long long int represented by the localized string s, using base base. If base is 0 the base is determined automatically using the following rules: If the string begins with "0x", it is assumed to be hexadecimal; if it begins with "0", it is assumed to be octal; otherwise it is assumed to be decimal.

If the conversion fails the function returns 0.

If ok is not 0, failure is reported by setting *ok to false, and success by setting *ok to true.

This function ignores leading and trailing whitespace.

See also toLongLong(), toInt(), toDouble(), and toString().

ushort QLocale::toUShort ( const QString & s, bool * ok = 0, int base = 0 ) const

Returns the unsigned short int represented by the localized string s, using base base. If base is 0 the base is determined automatically using the following rules: If the string begins with "0x", it is assumed to be hexadecimal; if it begins with "0", it is assumed to be octal; otherwise it is assumed to be decimal.

If the conversion fails the function returns 0.

If ok is not 0, failure is reported by setting *ok to false, and success by setting *ok to true.

This function ignores leading and trailing whitespace.

See also toShort() and toString().

QChar QLocale::zeroDigit () const

Returns the zero digit character of this locale.

This function was introduced in Qt 4.1.

bool QLocale::operator!= ( const QLocale & other ) const

Returns true if the QLocale object is not the same as the other locale specified; otherwise returns false.

QLocale & QLocale::operator= ( const QLocale & other )

Assigns other to this QLocale object and returns a reference to this QLocale object.

bool QLocale::operator== ( const QLocale & other ) const

Returns true if the QLocale object is the same as the other locale specified; otherwise returns false.