C++ constructor variable values at runtime will not be overridden [closed] - c++

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I am following a c++ course with Unity. I followed the instructor, but I halted at the part where he defines a constructor. For some reason the variables will not be overridden at runtime with the values I gave in the definition of my constructor.
Here is my code:
FBullCowGame.h
#pragma once
//#include <iostream>
#include <string>
class FBullCowGame {
public:
FBullCowGame();
void Reset() const; //TODO make a more rich return value
int GetMaxTries() const;
int GetCurrentTry() const;
bool CheckGuessValidity(std::string) const;
bool IsGameWon() const;
private:
int MyCurrentTry;
int MyMaxTries;
};
FBullCowGame.cpp
#include "FBullCowGame.h"
//#pragma region constructors
FBullCowGame::FBullCowGame() {
int MyCurrentTry = 666;
int MyMaxTries = 666;
}
//#pragma endregion
//#pragma region getters
void FBullCowGame::Reset() const { return; }
int FBullCowGame::GetMaxTries() const { return MyMaxTries; }
int FBullCowGame::GetCurrentTry() const { return MyCurrentTry; }
bool FBullCowGame::CheckGuessValidity(std::string) const { return false; }
bool FBullCowGame::IsGameWon() const { return false; }
//#pragma endregion
main.cpp
#include <iostream>
#include <string>
#include "FBullCowGame.h"
void PrintIntro();
void PlayGame();
std::string GetGuess();
bool AskToPlayAgain();
FBullCowGame BCGame;
int main() {
std::cout << BCGame.GetCurrentTry();
std::cout << BCGame.GetMaxTries();
bool bPlayAgain = false;
do {
PrintIntro();
PlayGame();
bPlayAgain = AskToPlayAgain();
} while (bPlayAgain);
return 0;
}
void PlayGame() {
int MaxTries = BCGame.GetMaxTries();
std::cout << MaxTries << "\n";
for (int i = 1; i <= MaxTries; i++) {
std::string Guess = GetGuess();
std::cout << "Your guess was: " << Guess << std::endl;
std::cout << std::endl;
}
}
void PrintIntro() {
constexpr int WORD_LENGTH = 9;
std::cout << "Welcome to Bulls and Cows, a fun word game.\n";
std::cout << "Can you guess the " << WORD_LENGTH;
std::cout << " letter isogram I'm thinking of?\n\n";
return;
}
//std::cout << "Your guess is: " << Guess << "\n\n";
std::string GetGuess() {
int CurrentTry = BCGame.GetCurrentTry();
std::string Guess = "";
std::cout << "Try " << CurrentTry << ". Enter your guess: ";
std::getline(std::cin, Guess);
return Guess;
}
bool AskToPlayAgain() {
std::cout << "Do you want to play again(y/n)? ";
std::string Response = "";
std::getline(std::cin, Response);
//std::cout << "First char is: " << ((Response[0] == 'y') || (Response[0] == 'Y')) << "\n";
return (Response[0] == 'y') || (Response[0] == 'Y');
}
I a outputting the values with these two lines inside main:
std::cout << BCGame.GetCurrentTry();
std::cout << BCGame.GetMaxTries();
I only get 0 for both values from the getter functions. I am a beginner in c++ and I need a bit of help. I was thinking it's an IDE problem, so I cleaned the solution, rebuilt, rerun, restarted the IDE and did that again. Any kind of help is appreciated. Thanks.

Answer 1

In your class declaration you have:
{
...
private:
int MyCurrentTry;
int MyMaxTries;
};
Then in your constructor you think you are initializing them with this:
FBullCowGame::FBullCowGame() {
int MyCurrentTry = 666;
int MyMaxTries = 666;
}
But what is actually happening here is that you are creating local stack variables with the same exact name as your class's members. Your class member variables can be seen by using the class's this pointer ->:
{
this->MyCurrentTry ...
this->MyMaxTries ...
}
as these two sets of variables are not the same. Your member variables are not even being initialized; the compiler might be smart enough to automatically initialize them with 0 but this isn't guaranteed as they can have any arbitrary value. You are only declaring and initializing stack variables that are local to the constructor only.
To fix this you have 3 options.
First it was already mentioned in the comments. Just remove the type int before the names in the constructor so that you are not declaring local variables but are actually using the members as such:
{
MyCurrentTry = 666;
MyMaxTries = 666;
}
The second option is to do the same but to use the class's this pointer ->
{
this->MyCurrentTry = 666;
this->MyMaxTries = 666;
}
The third and more preferred method is to use the class constructor's member initializer list.
FBullCowGame::FBullCowGame() :
MyCurrentTry( 666 ),
MyMaxTries( 666 ) {
}
This should explain what you was doing wrong within your class's constructor and why the variables were not being initialized to what you thought they should of been, and why you was getting the output you was seeing.
A side note; your class's Reset() function does absolutely nothing.
If you want to use it as you are thinking then you would want it to look like this:
// Remove the const qualifier; otherwise you will not able to modify
// the class's members with this function. "const" is usually good for
// methods that return a member that does not make any internal changes
// to the member or the class.
{
public:
void Reset();
};
FBullCowGame::Reset() {
MyCurrentTry = "whatever value to reset it to."
MyMaxTries = "whatever value to reset it to."
}