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Static Assertion – cppreference.com

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Original:

Performs compile-time assertion checking

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Syntax

static_assert ( bool_constexpr , string ) (seit C++11)

Erklärung

  • bool_constexpr einer Boolschen Konstante Ausdruck, der ausgewertet werden

    Original:

    bool_constexpr a boolean constant expression to be evaluated

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  • string Zeichenfolgenliteral, die als Compiler-Fehler, wenn bool_constexpr erscheint, ist falsch

    Original:

    string string literal that will appear as compiler error if bool_constexpr is false

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Beispiel

#include <type_traits>

template<class T>
    void swap( T& a, T& b)
    {
        static_assert(std::is_copy_constructible<T>::value,
                      "Swap requires copying");

        auto c = b;
        b = a;
        a = c;
    }

template<class T>
    struct data_structure
{
    static_assert(std::is_default_constructible<T>::value,
                  "Data Structure requires default-constructible elements");

};

struct no_copy
{
    no_copy ( const no_copy& ) = delete;
    no_copy () = default;
};

struct no_default
{
    no_default ( ) = delete;
};

int main()
{
    int a, b;
    swap(a,b);

    no_copy nc_a, nc_b;
    swap(nc_a,nc_b); // 1

    data_structure<int> ds_ok;
    data_structure<no_default> ds_error; // 2
}

Possible output: 

1: error: static assertion failed: Swap requires copying
2: error: static assertion failed: Data Structure requires default-constructible elements

Siehe auch