function template
<tuple>
std::tie
template<class... Types>
tuple<Types&...> tie (Types&... args) noexcept;
template<class... Types>
constexpr tuple<Types&...> tie (Types&... args) noexcept;
Tie arguments to tuple elements
Constructs a tuple object whose elements are references to the arguments in args, in the same order.
This allows a set of objects to act as a tuple, which is especially useful to unpack tuple objects.
The special constant ignore can be used to specify elements of a tuple to be ignored instead of tied to a specific object.
Parameters
- args
- List of objects (lvalues) to be tied as elements of a tuple.
Return Value
A tuple with lvalue references to args.
Example
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// packing/unpacking tuples
#include <iostream> // std::cout
#include <tuple> // std::tuple, std::make_tuple, std::tie
int main ()
{
int myint;
char mychar;
std::tuple<int,float,char> mytuple;
mytuple = std::make_tuple (10, 2.6, 'a'); // packing values into tuple
std::tie (myint, std::ignore, mychar) = mytuple; // unpacking tuple into variables
std::cout << "myint contains: " << myint << '\n';
std::cout << "mychar contains: " << mychar << '\n';
return 0;
}
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Output:
myint contains: 10
mychar contains: a
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Data races
None introduced by this call.
Notice though that the arguments may be modified by any use of the returned object.
Exception safety
No-throw guarantee: this function never throws exceptions.