Queries alignment requirements of a type.
[edit] SyntaxReturns a value of type std::size_t.
[edit] ExplanationReturns the alignment, in bytes, required for any instance of the type indicated by type-id, which is either complete object type, an array type whose element type is complete, or a reference type to one of those types.
If the type is reference type, the operator returns the alignment of referenced type; if the type is array type, alignment requirement of the element type is returned.
[edit] NotesSee alignment for the meaning and properties of the value returned by alignof.
#include <iostream>
struct Foo
{
int i;
float f;
char c;
};
// Note: alignas(alignof(long double)) below can be
// simplified to alignas(long double) if desired.
struct alignas(alignof(long double)) Foo2
{
// put your definition here
};
struct Empty {};
struct alignas(64) Empty64 {};
#define SHOW(expr) std::cout << #expr << " = " << (expr) << '\n'
int main()
{
SHOW(alignof(char));
SHOW(alignof(int*));
SHOW(alignof(Foo));
SHOW(alignof(Foo2));
SHOW(alignof(Empty));
SHOW(alignof(Empty64));
}
Possible output:
alignof(char) = 1 alignof(int*) = 8 alignof(Foo) = 4 alignof(Foo2) = 16 alignof(Empty) = 1 alignof(Empty64) = 64[edit] Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR Applied to Behavior as published Correct behavior CWG 1305 C++11 type-id could not represent a reference to an arrayRetroSearch is an open source project built by @garambo | Open a GitHub Issue
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