std::tie

From Cppreference

Defined in header `<tuple>`

template< class... Types > tuple<Types&...> tie( Types&... args );		(C++11 feature)

Creates a tuple of lvalue references to its arguments or instances of std::ignore.

#include <iostream>
#include <string>
#include <set>
#include <tuple>
 
struct S {
    int n;
    std::string s;
    float d;
    bool operator<(const S& rhs) const
    {
        return std::tie(n, s, d) < std::tie(rhs.n, rhs.s, rhs.d);
    }
};
 
int main()
{
    std::set<S> set_of_s; // S is LessThanComparable
 
    S value{42, "Test", 3.14};
    std::set<S>::iterator iter;
    bool inserted;
    std::tie(iter, inserted) = set_of_s.insert(value);
    if(inserted)
        std::cout << "Value was inserted sucessfully\n";
}

Output:

Value was inserted sucessfully

make_tuple

creates a tuple object of the type defined by the argument types
(function template)

forward_as_tuple

creates a tuple of rvalue references
(function template)

tuple_cat

creates a tuple by concatenating any number of tuples
(function template)

ignore

placeholder to skip an element when unpacking a tuple using tie
(constant)

std::tie

From Cppreference

Contents

[edit] Parameters

[edit] Return value

[edit] Exceptions

[edit] Example


noexcept