Creating a thread inside the class in C++ - c++

Question

I am a beginner in threading with C++. Tried to create a thread t1 inside the class, but I want it not to be initialized. For this I did:
In the class variable, thread *t1 as if were to declare the class variable without initializing it.
Then from the constructor, I did:
t1 = new Thread(functionName);
But, there's some error that I didn't get. I previously had simple working experience with threading in Java.
Will this strategy cause an interlocking problem, assuming the solution exists to the way I want to implement it. (if I want to access the same variable without modifying it). Code goes like this:
class game:protected gameObjects
{
thread *t1;
///-------------------- Variables-------------------///
char keyPressed = NULL;
/// structure for holding player information.
struct player
{
int x, y0, y1,color;
};
player player1, player2;
/// for ball
int ballX, ballY, ballColor, ballBorderColor;
///--------------------------------------------------///
void initializeData()
{
ballX = 42;
ballY = 130;
player1.color = LIGHTCYAN;
player1.x = 30;
player1.y0 = 100;
player1.y1 = 200;
player2.color = LIGHTMAGENTA;
player2.x = 600;
player2.y0 = 100;
player2.y1 = 200;
/// Basic setUp For Game and Game Screen
ballBorderColor = RED;
ballColor = GREEN;
}
void updateScoreBoard()
{
/// whole score board border.
drawRect(20,10,620,50,RED);
/// left score board
drawRect(21,11,321,49,CYAN);
setfillstyle(SOLID_FILL,CYAN);
floodfill(30,40,CYAN);
setbkcolor(CYAN);
setcolor(LIGHTGREEN);
outtextxy(35,20,"Score:0");
///right score board.
drawRect(323,11,619,49,LIGHTMAGENTA);
setfillstyle(SOLID_FILL,LIGHTMAGENTA);
floodfill(330,40,LIGHTMAGENTA);
setbkcolor(LIGHTMAGENTA);
setcolor(LIGHTGREEN);
outtextxy(350,20,"Score:1");
}
void ballPosition()
{
setfillstyle(SOLID_FILL,ballColor);
drawCircle(ballX,ballY,10,ballBorderColor); ///ball for game
floodfill(ballX,ballY,ballBorderColor);
}
void playerBatPosition()
{
drawLine(player1.x,player1.y0,player1.x,player1.y1,player1.color);
drawLine(player2.x,player2.y0,player2.x,player2.y1,player2.color);
}
void setBackground()
{
setfillstyle(SOLID_FILL,background);
drawRect(0,0,getmaxx(),getmaxy(),RED);
floodfill(getmaxx()/2,getmaxy()/2,RED);
drawRect(20,60,620,470,WHITE); ///white line.
}
void updateScreenActivity()
{
playerBatPosition();
}
void startPlaying()
{
do
{
keyPressed = _getch();
if(keyPressed == 'w')
{
if(player1.y0 > 60)
{
drawLine(player1.x,player1.y0,player1.x,player1.y1,background);
player1.y0-=5;
player1.y1-=5;
}
}
else if(keyPressed == 's')
{
if(player1.y1 < 470)
{
drawLine(player1.x,player1.y0,player1.x,player1.y1,background);
player1.y0+=5;
player1.y1+=5;
}
}
if(keyPressed == 't')
{
if(player2.y0 > 60)
{
drawLine(player2.x,player2.y0,player2.x,player2.y1,background);
player2.y0-=5;
player2.y1-=5;
}
}
else if(keyPressed == 'g')
{
if(player2.y1 < 470)
{
drawLine(player2.x,player2.y0,player2.x,player2.y1,background);
player2.y0+=5;
player2.y1+=5;
}
}
updateScreenActivity();
}
while(keyPressed != 'q');
}
///-------------------Threading call --------------///
void startBallMovement(){
cout<<"Hello world"<<endl;
}
///-----------------------------------------------///
public:
game()
{
cleardevice();
initializeData();
setBackground();
updateScoreBoard();
playerBatPosition();
ballPosition();
startPlaying();
t1 = new thread(startBallMovement);
}
};
What I want to do is create a movement of a circle in different paths from the thread. I might sometimes need to access the variables from the thread to simulate the movement in different directions as per the user's strategy.
Error:

Answer 1

Your class implementation looks a bit lousy. But try something like this.
class game
{
private: thread* t;
public:
game()
{
t = new thread([this]() {startBallMovement();} );
}
~game()
{
if(t != nullptr)
{
t->join();
delete t;
}
}
void startBallMovement()
{
}
};