public member function
<unordered_map>

std::unordered_map::empty

bool empty() const noexcept;
Test whether container is empty
Returns a bool value indicating whether the unordered_map container is empty, i.e. whether its size is 0.

This function does not modify the content of the container in any way. To clear the content of an array object, member function unordered_map::clear exists.

Parameters

none

Return Value

true if the container size is 0, false otherwise.

Example

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// unordered_map::empty
#include <iostream>
#include <unordered_map>

int main ()
{
  std::unordered_map<int,int> first;
  std::unordered_map<int,int> second = {{1,10},{2,20},{3,30}};
  std::cout << "first " << (first.empty() ? "is empty" : "is not empty" ) << std::endl;
  std::cout << "second " << (second.empty() ? "is empty" : "is not empty" ) << std::endl;
  return 0;
}


Output:
first is empty
second is not empty

Complexity

Constant.

Iterator validity

No changes.

See also

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