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sizeof operator

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Abfragen Größe des Objekts oder Typ
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Queries size of the object or type
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Verwendet werden, wenn tatsächliche Größe des Objekts bekannt sein
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Used when actual size of the object must be known
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Inhaltsverzeichnis

[Bearbeiten] Syntax

sizeof( type )
sizeof expression None
Beide Versionen geben eine Konstante vom Typ std::size_t .
Original:
Both versions return a constant of type std::size_t.
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[Bearbeiten] Erklärung

1)
Renditen Größe in Bytes des Objekts Darstellung type .
Original:
returns size in bytes of the object representation of type.
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2)
Renditen Größe in Bytes des Objekts Darstellung des Typs, das wäre von expression zurückgegeben werden, wenn beurteilt .
Original:
returns size in bytes of the object representation of the type, that would be returned by expression, if evaluated.
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[Bearbeiten] Notes

sizeof(char), sizeof(signed char) und sizeof(unsigned char) immer 1 zurückzukehren, unabhängig vom Wert des CHAR_BIT .
Original:
sizeof(char), sizeof(signed char), and sizeof(unsigned char) always return 1, regardless of the value of CHAR_BIT.
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sizeof kann nicht mit Funktionstypen, unvollständigen Typen oder Bit-Feld lvalues ​​verwendet werden .
Original:
sizeof cannot be used with function types, incomplete types, or bit-field lvalues.
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Bei Anschluss an einen Referenztyp angewendet, ist das Ergebnis die Größe des referenzierten Typs .
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When applied to a reference type, the result is the size of the referenced type.
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Wenn zu einer Klasse-Typ angewendet wird, ist das Ergebnis die Größe eines Objekts dieser Klasse zuzüglich zusätzlicher Polsterung erforderlich, um ein solches Objekt in einem Array platzieren .
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When applied to a class type, the result is the size of an object of that class plus any additional padding required to place such object in an array.
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Wenn Sie mit einem leeren Klasse Typs angewendet, immer 1 zurück .
Original:
When applied to an empty class type, always returns 1.
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[Bearbeiten] Keywords

sizeof

[Bearbeiten] Beispiel

Das Beispiel Ausgang entspricht einem System mit 64-Bit-Zeiger und 32-Bit-int .
Original:
The example output corresponds to a system with 64-bit pointers and 32-bit int.
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#include <iostream>
struct Empty {};
struct Bit {unsigned bit:1; };
int main()
{
    Empty e;
    Bit b;
    std::cout << "size of empty class: "     << sizeof e        << '\n'
              << "size of pointer : "        << sizeof &e       << '\n'
//            << "size of function: "        << sizeof(void())  << '\n'  // compile error
//            << "size of incomplete type: " << sizeof(int[])   << '\n'  // compile error
//            << "size of bit field: "       << sizeof b.bit    << '\n'  // compile error
              << "size of array of 10 int: " << sizeof(int[10]) << '\n';
}

Output:

size of empty class: 1
size of pointer : 8
size of array of 10 int: 40

[Bearbeiten] Siehe auch