Provides the member constantvalue equal to thealignment requirement of the typeT, as if obtained by analignof expression. IfT is an array type, returns the alignment requirements of the element type. IfT is a reference type, returns the alignment requirements of the type referred to.

Ifalignof(T) is not a valid expression, the behavior is undefined.

If the program adds specializations forstd::alignment_of orstd::alignment_of_v(since C++17), the behavior is undefined.

[edit] Helper variable template

[edit]Possible implementation

template<class T>struct alignment_of:std::integral_constant<std::size_t, alignof(T)>{};

[edit]Notes

This type trait predates thealignof keyword, which can be used to obtain the same value with less verbosity.

[edit]Example

#include <cstdint>#include <iostream>#include <type_traits> struct A{};struct B{std::int8_t p;std::int16_t q;}; int main(){std::cout<< std::alignment_of<A>::value<<' ';std::cout<< std::alignment_of<B>::value<<' ';std::cout<< std::alignment_of<int>()<<' ';// alt syntaxstd::cout<< std::alignment_of_v<double><<'\n';// c++17 alt syntax}

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[edit]See also

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