Using Member Functions as Predicates with std::ranges::any_of()

Using std::ranges::any_of() with a member function that requires parameters involves binding the required parameters to the function. The std::bind utility or lambdas can help with this. Here's an example:

1#include <algorithm>
2#include <iostream>
3#include <vector>
4#include <functional>
5
Player Class|Show
6class Player {/*...*/};
20
21int main() {
22  std::vector<Player> Party {
23    Player{"Roderick", 100},
24    Player{"Anna", 50},
25    Player{"Robert", 150}
26  };
27
28  int threshold = 100;
29  auto isHealthy = [&](const Player& p) {
30    return p.hasHealthGreaterThan(threshold); 
31  };
32
33  bool anyHealthy = std::ranges::any_of(
34    Party, isHealthy); 
35
36  std::cout
37    << "Any player with health greater than "
38    << threshold << "? "
39    << (anyHealthy ? "Yes" : "No");
40}

1Any player with health greater than 100? Yes

In this example:

• The Player class has a member function hasHealthGreaterThan() that checks if a player's health exceeds a given threshold.
• In the main() function, we create a lambda isHealthy that binds the threshold variable and calls hasHealthGreaterThan().
• We then pass this lambda to std::ranges::any_of() to check if any player in the Party vector has health greater than the threshold.

This technique can be adapted to other member functions requiring parameters.

By using lambdas or std::bind, you can effectively use member functions with std::ranges algorithms, enhancing the flexibility and reusability of your code.