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Class template designed to access the number of elements in a tuple (as a
The class is itself undefined for the generic type T, but a specialization for tuple instantiations is defined in the
A specialization for this class template also exists for the tuple-like types array and pair in their respective headers, also having a value member defined to the appropriate
For
Output:
Reference
C library:
- <cassert> (assert.h)
- <cctype> (ctype.h)
- <cerrno> (errno.h)
-
<cfenv> (fenv.h)C++11
- <cfloat> (float.h)
-
<cinttypes> (inttypes.h)C++11
- <ciso646> (iso646.h)
- <climits> (limits.h)
- <clocale> (locale.h)
- <cmath> (math.h)
- <csetjmp> (setjmp.h)
- <csignal> (signal.h)
- <cstdarg> (stdarg.h)
-
<cstdbool> (stdbool.h)C++11
- <cstddef> (stddef.h)
-
<cstdint> (stdint.h)C++11
- <cstdio> (stdio.h)
- <cstdlib> (stdlib.h)
- <cstring> (string.h)
-
<ctgmath> (tgmath.h)C++11
- <ctime> (time.h)
-
<cuchar> (uchar.h)C++11
- <cwchar> (wchar.h)
- <cwctype> (wctype.h)
Containers:
-
<array>C++11
- <deque>
-
<forward_list>C++11
- <list>
- <map>
- <queue>
- <set>
- <stack>
-
<unordered_map>C++11
-
<unordered_set>C++11
- <vector>
-
Input/Output:
Multi-threading:
-
<atomic>C++11
-
<condition_variable>C++11
-
<future>C++11
-
<mutex>C++11
-
<thread>C++11
-
Other:
- <algorithm>
- <bitset>
-
<chrono>C++11
-
<codecvt>C++11
- <complex>
- <exception>
- <functional>
-
<initializer_list>C++11
- <iterator>
- <limits>
- <locale>
- <memory>
- <new>
- <numeric>
-
<random>C++11
-
<ratio>C++11
-
<regex>C++11
- <stdexcept>
- <string>
-
<system_error>C++11
-
<tuple>C++11
-
<type_traits>C++11
-
<typeindex>C++11
- <typeinfo>
- <utility>
- <valarray>
<tuple>
classes
-
tupleC++11
-
tuple_elementC++11
-
tuple_sizeC++11
-
functions
-
forward_as_tupleC++11
-
getC++11
-
make_tupleC++11
-
tieC++11
-
tuple_catC++11
-
objects
-
ignoreC++11
-
class template
<tuple>
std::tuple_size
| unspecialized | template <class T> class tuple_size; |
|---|---|
| generic cv-specializations | template <class T> class tuple_size<const T>;template <class T> class tuple_size<volatile T>;template <class T> class tuple_size<const volatile T>; |
| tuple specialization | template <class... Types> struct tuple_size<tuple<Types...> >; |
Tuple size traits
constexpr).The class is itself undefined for the generic type T, but a specialization for tuple instantiations is defined in the
<tuple> header as: |
|
A specialization for this class template also exists for the tuple-like types array and pair in their respective headers, also having a value member defined to the appropriate
constexpr value.For
const and/or volatile-qualified tuples and tuple-like objects, the class is specialized so that its value member is itself non cv-qualified (size_t for tuples).Template parameters
Member constants
| member constant | definition |
|---|---|
| value | The number of elements in the tuple or tuple-like object. This is a constexpr value of the unsigned integral type size_t. |
Example
|
|
Output:
mytuple has 3 elements |
See also
- tuple
- Tuple (class template)
- tuple_element
- Tuple element type (class template)
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Spotted an error? contact us