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You can use std::call_once with a lambda to call the function the first time you find a game master like

void PrintToGameMasters()

 std::once_flag of;
 std::string message;
 for (Player* player : GetAllPlayers())
 if (player->IsGameMaster())
 
 std::call_once(of, [&]() message = GetComplicatedDebugMessage(); );
 player->SendMessage(message);
 

Some good ideas here, but I like to keep it a bit more simple:

void PrintToGameMasters()

 std::string message;

 for (Player* player : GetAllPlayers())
 
 if (player->IsGameMaster())
 
 if (message.empty())
 message = GetComplicatedDebugMessage();

 player->SendMessage(message);
 
 

Everybody can follow this, and it's cheap as chips… plus it's easy as pie to debug.

Wrap the message in a mutable lambda:

auto makeMessage = [message = std::string()]() mutable -> std::string&

 if (message.empty()) 
 message = GetComplicatedDebugMessage();
 
 return message;
;

for (Player* player : GetAllPlayers())
 if (player->IsGameMaster())
 player->SendMessage(makeMessage());

Use data-oriented design; keep two lists of players: game masters and non-game masters.

void PrintToGameMasters()

 auto players = GetGameMasters(); // Returns ONLY game master players
 if (players.begin() != players.end()) 
 std::string message = GetComplicatedDebugMessage();
 for (Player* player : players) 
 player->SendMessage(message);
 
 

The goal is to minimize if-statements inside loops.

P.S. Since you're developing a game, I want to add this link to Mike Acton's cppcon talk which you might find interesting.

Whereas std::string has empty value which might mean "not computed", you might use more generally std::optional which handle empty string and non default constructible types:

void PrintToGameMasters()

 std::optional<std::string> message;

 for (Player* player : GetAllPlayers())
 
 if (player->IsGameMaster())
 
 if (!message)
 message = GetComplicatedDebugMessage();

 player->SendMessage(*message);
 
 

Not sure if this is the best pattern, but you can delay computation with a lambda:

void PrintToGameMasters()

 std::string message = "";
 auto getDebugMessage = [&message]() -> const std::string& 
 if (message.empty()) 
 message = GetComplicatedDebugMessage();
 
 return message;
 ;

 for (Player* player : GetAllPlayers())
 if (player->IsGameMaster())
 player->SendMessage(getDebugMessage());

Another simplistic approach using static keyword:

void PrintToGameMasters()
 
 for (Player* player : GetAllPlayers())
 if (player->IsGameMaster())
 
 static std::string message = GetComplicatedDebugMessage();
 player->SendMessage(message);
 

Really hope this helps

Try maybe implement this logic:

#include <iostream>

using namespace std;

int main()

 bool GameMaster,first_time,used_before;

 GameMaster = true;
 first_time = false;
 used_before = false;

 GameMaster = first_time;
 first_time = used_before;


 for( int i = 0; i < 5; i++ ) 

 if(GameMaster==used_before) 
 cout<<" First Time";
 GameMaster = true;
 

 if(GameMaster!=used_before) 
 cout<<" Old News";
 


 return 0;

With Response:

 First Time Old News Old News Old News Old News Old News