.key_comp

The .key_comp() function returns a copy of the comparison function object (typically key_compare) used by the container to order its keys.

Syntax

myMap.key_comp();

Parameters:

• .key_comp() takes no parameters.

Return value:

• Returns the key comparison function object used by the map to order its keys.
  • By default, this is std::less<Key> unless a custom comparator was specified when defining the map.

Example

This is an example demonstrating how to use .key_comp() to compare keys in a std::map:

#include <iostream>
#include <map>

int main() {

  std::map<int, std::string> myMap = {
    {1, "Apple"},
    {2, "Banana"},
    {3, "Orange"},
    {4, "Date"},
    {5, "Mango"}
  };

  auto comp = myMap.key_comp();

  int keyToCompare = 3;

  for (const auto& pair : myMap) {
    if (comp(pair.first, keyToCompare)) {
      std::cout << pair.first << " is less than " << keyToCompare << std::endl;
    } else if (comp(keyToCompare, pair.first)) {
        std::cout << pair.first << " is greater than " << keyToCompare << std::endl;
      } else {
          std::cout << pair.first << " is equal to " << keyToCompare << std::endl;
        }
  }

  return 0;
}

Copy to clipboard
Copy to clipboard

The output of this code will be:

1 is less than 3
2 is less than 3
3 is equal to 3
4 is greater than 3
5 is greater than 3

Copy to clipboard
Copy to clipboard

Codebyte Example

This is a codebyte example demonstrating how to use .key_comp() to compare keys in a std::map:

Visit us
Visit us
Hide code
Code
Output
Hide output
Loading...
Copy to your clipboard
Copy Codebyte
Run