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[править] QLatin1String Class Reference
^{[модуль QtCore ]}

The QLatin1String class provides a thin wrapper around an ASCII/Latin-1 encoded string literal. Далее...

 #include <QLatin1String>

Примечание: все функции в этом классе реентерабельны.

• Список всех членов, включая унаследованные

[править] Открытые функции

• QLatin1String ( const char * str )
• const char * latin1 () const
• bool operator!= ( const QString & other ) const
• bool operator!= ( const char * other ) const
• bool operator< ( const QString & other ) const
• bool operator< ( const char * other ) const
• bool operator<= ( const QString & other ) const
• bool operator<= ( const char * other ) const
• QLatin1String & operator= ( const QLatin1String & other )
• bool operator== ( const QString & other ) const
• bool operator== ( const char * other ) const
• bool operator> ( const QString & other ) const
• bool operator> ( const char * other ) const
• bool operator>= ( const QString & other ) const
• bool operator>= ( const char * other ) const

[править] Подробное описание

The QLatin1String class provides a thin wrapper around an ASCII/Latin-1 encoded string literal.

Many of QString's member functions are overloaded to accept const char * instead of QString. This includes the copy constructor, the assignment operator, the comparison operators, and various other functions such as insert(), replace(), and indexOf(). These functions are usually optimized to avoid constructing a QString object for the const char * data. For example, assuming str is a QString,

 if (str == "auto" || str == "extern"
         || str == "static" || str == "register") {
     ...
 }

is much faster than

 if (str == QString("auto") || str == QString("extern")
         || str == QString("static") || str == QString("register")) {
     ...
 }

because it doesn't construct four temporary QString objects and make a deep copy of the character data.

Applications that define QT_NO_CAST_FROM_ASCII (as explained in the QString documentation) don't have access to QString's const char * API. To provide an efficient way of specifying constant Latin-1 strings, Qt provides the QLatin1String, which is just a very thin wrapper around a const char *. Using QLatin1String, the example code above becomes

 if (str == QLatin1String("auto")
         || str == QLatin1String("extern")
         || str == QLatin1String("static")
         || str == QLatin1String("register") {
     ...
 }

This is a bit longer to type, but it provides exactly the same benefits as the first version of the code, and is faster than converting the Latin-1 strings using QString::fromLatin1().

Thanks to the QString(const QLatin1String &) constructor, QLatin1String can be used everywhere a QString is expected. Пример:

 QLabel *label = new QLabel(QLatin1String("MOD"), this);

See also QString and QLatin1Char.

[править] Описание функций-членов

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QLatin1String::QLatin1String ( const char * str )

Constructs a QLatin1String object that stores str.

The string data is not copied. The caller must be able to guarantee that str will not be deleted or modified as long as the QLatin1String object exists.

See also latin1().

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const char * QLatin1String::latin1 () const

Returns the Latin-1 string stored in this object.

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bool QLatin1String::operator!= ( const QString & other ) const

Returns true if this string is not equal to string other; otherwise returns false.

The comparison is based exclusively on the numeric Unicode values of the characters and is very fast, but is not what a human would expect. Consider sorting user-interface strings with QString::localeAwareCompare().

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bool QLatin1String::operator!= ( const char * other ) const

Эта перегруженная функция предоставлена для удобства.

The other const char pointer is converted to a QLatin1String using the QString::fromAscii() function.

You can disable this operator by defining QT_NO_CAST_FROM_ASCII when you compile your applications. This can be useful if you want to ensure that all user-visible strings go through QObject::tr(), for example.

Эта функция была введена в Qt 4.3.

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bool QLatin1String::operator< ( const QString & other ) const

Returns true if this string is lexically less than the other string; otherwise returns false.

The comparison is based exclusively on the numeric Unicode values of the characters and is very fast, but is not what a human would expect. Consider sorting user-interface strings using the QString::localeAwareCompare() function.

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bool QLatin1String::operator< ( const char * other ) const

Эта перегруженная функция предоставлена для удобства.

The other const char pointer is converted to a QLatin1String using the QString::fromAscii() function.

You can disable this operator by defining QT_NO_CAST_FROM_ASCII when you compile your applications. This can be useful if you want to ensure that all user-visible strings go through QObject::tr(), for example.

Эта функция была введена в Qt 4.3.

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bool QLatin1String::operator<= ( const QString & other ) const

Returns true if this string is lexically less than or equal to string other; otherwise returns false.

The comparison is based exclusively on the numeric Unicode values of the characters and is very fast, but is not what a human would expect. Consider sorting user-interface strings with QString::localeAwareCompare().

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bool QLatin1String::operator<= ( const char * other ) const

Эта перегруженная функция предоставлена для удобства.

The other const char pointer is converted to a QString using the QString::fromAscii() function.

You can disable this operator by defining QT_NO_CAST_FROM_ASCII when you compile your applications. This can be useful if you want to ensure that all user-visible strings go through QObject::tr(), for example.

Эта функция была введена в Qt 4.3.

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QLatin1String & QLatin1String::operator= ( const QLatin1String & other )

Создаёт копию other.

Эта функция была введена в Qt 4.1.

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bool QLatin1String::operator== ( const QString & other ) const

Returns true if this string is equal to string other; otherwise returns false.

The comparison is based exclusively on the numeric Unicode values of the characters and is very fast, but is not what a human would expect. Consider sorting user-interface strings with QString::localeAwareCompare().

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bool QLatin1String::operator== ( const char * other ) const

Эта перегруженная функция предоставлена для удобства.

The other const char pointer is converted to a QLatin1String using the QString::fromAscii() function.

You can disable this operator by defining QT_NO_CAST_FROM_ASCII when you compile your applications. This can be useful if you want to ensure that all user-visible strings go through QObject::tr(), for example.

Эта функция была введена в Qt 4.3.

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bool QLatin1String::operator> ( const QString & other ) const

Returns true if this string is lexically greater than string other; otherwise returns false.

The comparison is based exclusively on the numeric Unicode values of the characters and is very fast, but is not what a human would expect. Consider sorting user-interface strings with QString::localeAwareCompare().

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bool QLatin1String::operator> ( const char * other ) const

Эта перегруженная функция предоставлена для удобства.

The other const char pointer is converted to a QLatin1String using the QString::fromAscii() function.

You can disable this operator by defining QT_NO_CAST_FROM_ASCII when you compile your applications. This can be useful if you want to ensure that all user-visible strings go through QObject::tr(), for example.

Эта функция была введена в Qt 4.3.

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bool QLatin1String::operator>= ( const QString & other ) const

Returns true if this string is lexically greater than or equal to string other; otherwise returns false.

The comparison is based exclusively on the numeric Unicode values of the characters and is very fast, but is not what a human would expect. Consider sorting user-interface strings with QString::localeAwareCompare().

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bool QLatin1String::operator>= ( const char * other ) const

Эта перегруженная функция предоставлена для удобства.

The other const char pointer is converted to a QLatin1String using the QString::fromAscii() function.

You can disable this operator by defining QT_NO_CAST_FROM_ASCII when you compile your applications. This can be useful if you want to ensure that all user-visible strings go through QObject::tr(), for example.

Эта функция была введена в Qt 4.3.