User-defined literals (dal C++11)
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C + 11 ha introdotto la possibilità di aggiungere suffissi personalizzati per letterali, al fine di fornire valori diversi.
Original:
C++11 introduced the ability to add custom suffixes to literals in order to provide different values.
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Suffisso letterale può essere sovraccaricato in modo molto simile agli operatori.
Original:
Literal suffixed can be overloaded in a way very similar to operators.
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[modifica] Sintassi
return decl operator"" name ( unsigned long long n ) { body }
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return decl operator"" name ( long double d ) { body }
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return decl operator"" name ( char c ) { body }
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return decl operator"" name ( const char* str, size_t sz ) { body }
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return decl operator"" name ( const char* cstr ) { body }
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[modifica] Spiegazione
| return | - | Valore di ritorno
Original: Return value The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| decl | - | Dichiarazione sequenza specificatore, può contenere le parole chiave come constexpr o inline
Original: Declaration specifier sequence, can contain keywords as constexpr or inline The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| name | - | Un valido C + + identificatore, preceduto da un carattere di sottolineatura. Identificatori senza sottolineatura sono riservati per uso futuro
Original: A valid C++ identifier, prefixed with an underscore. Identifiers without underscore are reserved for future use The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| n | - | Valore risultante da un letterale integrale
Original: Value resulting from an integral literal The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| d | - | Valore risultante da una virgola letterale
Original: Value resulting from a floating-point literal The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| c | - | Valore risultante da un carattere letterale
Original: Value resulting from a character literal The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| cstr | - | Stringa null-terminated, come analizzato dal compilatore, per i valori letterali interi e virgola mobile
Original: Null-terminated string as parsed by the compiler, for integer and floating point literals The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| str/sz | - | Buffer e le dimensioni da una stringa letterale
Original: Buffer and size from a string literal The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| body | - | Funzione del corpo
Original: Function body The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
[modifica] Esempi
// used as conversion inline constexpr long double operator"" _deg ( long double deg ) { return deg*3.141592/180; } ... double x = 90.0_deg; // x = 1.570796
// used with custom type struct mytype { ... mytype ( unsigned long long ); }; mytype operator"" _mytype ( unsigned long long n ) { return mytype(n); } ... mytype x = 123_mytype;
// used for side-effects void operator"" _print ( const char* str ) { std::cout << str; } ... 0x123ABC_print;
Output:
0x123ABC
