Defined in header <tuple> | ||
|---|---|---|
const /*unspecified*/ ignore; | (since C++11) (until C++17) | |
inline constexpr /*unspecified*/ ignore; | (since C++17) |
An object of unspecified type such that any value can be assigned to it with no effect. Intended for use with std::tie when unpacking a std::tuple, as a placeholder for the arguments that are not used.
unpack a pair returned by set.insert(), but only save the boolean.
#include <iostream>
#include <string>
#include <set>
#include <tuple>
int main()
{
std::set<std::string> set_of_str;
bool inserted;
std::tie(std::ignore, inserted) = set_of_str.insert("Test");
if (inserted) {
std::cout << "Value was inserted successfully\n";
}
}Output:
Value was inserted successfully
creates a tuple of lvalue references or unpacks a tuple into individual objects (function template) |
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