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(). 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::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::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:

    Copyright (c) 1991 by AT&T.

    Permission to use, copy, modify, and distribute this software for any
    purpose without fee is hereby granted, provided that this entire notice
    is included in all copies of any software which is or includes a copy
    or modification of this software and in all copies of the supporting
    documentation for such software.

    THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
    WARRANTY.  IN PARTICULAR, NEITHER THE AUTHOR NOR AT&T MAKES ANY
    REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
    OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.

    This product includes software developed by the University of
    California, Berkeley and its contributors.

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::Language

This enumerated type is used to specify a language.

See also language().

Member Function Documentation

QLocale::QLocale ()

Constructs a QLocale object initialized with the default locale.

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().

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().

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().

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().

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().

QLocale QLocale::system ()   [static]

Returns a QLocale object initialized to the system locale.

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

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 ( qulonglong i ) const

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

See also toULongLong().

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

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

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. It behaves essentially like the above function.

See also toShort().

QString QLocale::toString ( ushort i ) const

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

See also toUShort().

QString QLocale::toString ( int i ) const

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

See also toInt().

QString QLocale::toString ( uint i ) const

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

See also toUInt().

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

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

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

See also toDouble().

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().

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.