Error: No matching function for call to Monster::Monster() - c++

Question

I tried to write a simple game and I accidently got errors
"No matching function for call to Monster::Monster()"
and
"No matching function for call to Player::Player()".
Both were for the Game class constructor. Class Game is not related to classes Monster or Player in any way. Here are the codes.
main.cpp
#include <game.h>
#include <iostream>
using namespace std;
int main() {
Game game = Game( );
while(!game.hasFinished( )) {
game.round( );
}
}
game.h
#ifndef GAME
#define GAME
#include <entity.h>
class Game {
private:
bool finished = false;
char area[15][15];
char defaultSign = '*';
int size = 15;
Monster monsters[4];
Player player;
int score = 0;
void cls();
void fill();
void display();
void playerMove();
public:
Game();
void round();
int getScore();
bool hasFinished();
};
#endif
game.cpp
#include <game.h>
#include <iostream>
#include <conio.h>
Game::Game() {
player = Player(7, 7);
monsters[0] = Monster(0, 0);
monsters[1] = Monster(size - 1, size - 1);
monsters[2] = Monster(size - 1, 0);
monsters[3] = Monster(0, size - 1);
}
bool Game::hasFinished() {
return !finished;
}
int Game::getScore() {
return score;
}
void Game::cls() {
for(int i = 0; i < 50; i++) {
std::cout << "\n";
}
}
void Game::fill() {
for(int i = 0; i < size; i++) {
for(int j = 0; j < size; j++) {
area[i][j] = defaultSign;
}
}
for(int i = 0; i < 4; i++) {
area[monsters[i].getX( )][monsters[i].getY( )] = monsters[i].getSign( );
}
area[player.getX( )][player.getY( )] = player.getSign( );
}
void Game::display() {
for(int i = 0; i < size; i++) {
for(int j = 0; j < size; j++) {
std::cout << area[i][j];
}
std::cout << "\n";
}
}
void Game::round() {
cls( );
fill( );
display( );
playerMove( );
for(int i = 0; i < 4; i++) {
monsters[i].moveTowards(player);
}
score++;
}
void Game::playerMove() {
bool moved = false;
while(!moved) {
char c = getch( );
if(c == 'w' || c == 'W') {
player.move(player.getX( ), player.getY( ) + 1);
moved = true;
}
if(c == 'a' || c == 'A') {
player.move(player.getX( ) - 1, player.getY( ));
moved = true;
}
if(c == 's' || c == 'S') {
player.move(player.getX( ), player.getY( ) - 1);
moved = true;
}
if(c == 'd' || c == 'D') {
player.move(player.getX( ) + 1, player.getY( ));
moved = true;
}
}
}
entity.h
#ifndef ENTITY
#define ENTITY
class Entity {
protected:
int x, y;
char sign;
public:
Entity(int xPos, int yPos);
int getX();
int getY();
void move(int xPos, int yPos);
char getSign();
};
class Player : public Entity {
private:
char sign = 'P';
public:
Player(int xPos, int yPos);
};
class Monster : public Entity {
private:
char sign = 'M';
public:
Monster(int xPos, int yPos);
void moveTowards(Entity p);
};
#endif
entity.cpp
#include <entity.h>
Entity::Entity(int xPos, int yPos) {
x = xPos;
y = yPos;
sign = '*';
}
void Entity::move(int xPos, int yPos) {
x = xPos;
y = yPos;
}
int Entity::getX() {
return x;
}
int Entity::getY() {
return y;
}
char Entity::getSign() {
return sign;
}
Player::Player(int xPos, int yPos)
: Entity(xPos, yPos) {
}
Monster::Monster(int xPos, int yPos)
: Entity(xPos, yPos) {
}
void Monster::moveTowards(Entity p) {
int moveArea[2] = {x, y};
if(x > p.getX( )) moveArea[0]--;
if(x < p.getX( )) moveArea[0]++;
if(y > p.getY( )) moveArea[1]--;
if(y < p.getY( )) moveArea[1]++;
move(moveArea[0], moveArea[1]);
}
Please, help!

Answer 1

The problem is
Monster monsters[4]; // ---> Means initiliaze 4 Monsters with a ctor which takes no arguments(eg default Ctor)
Player player; ---> //The initiliaze 1 Player with a ctor which take no arguments
Since you defined Monster(int xPos, int yPos); default Ctors are deleted. You have to define them yourself. Entity has the same problem. I compiled your code , if you do like below it will work.
Add "Entity() = default;" , initiliaze x and y like below,
class Entity {
protected:
int x = 0; --> Critical
int y = 0; --> Critical
char sign;
public:
Entity() = default; --> Critical
Entity(int xPos, int yPos);
int getX();
int getY();
void move(int xPos, int yPos);
char getSign();
};
Do the same for player and monster
class Monster : public Entity {
private:
char sign = 'M';
public:
Monster(int xPos, int yPos);
Monster() = default; --> Critical
void moveTowards(Entity p);
};
class Player : public Entity {
private:
char sign = 'P';
public:
Player() = default; --> Critical
Player(int xPos, int yPos);
};

Answer 2

You should add a default constructor to your Monster class because it's implicitly called when the Monster array is initialized. If you don't want to do that for some reason, you could change the Monster array contain raw or smart pointers to Monster objects.