Using your own shape classes

#include "pch.h"
#include <iostream>
#include <SFML/Graphics.hpp>
#include <SFML/Window.hpp>

using namespace std;

int width = 800;
int height = 600;

class Player
{
public:
    sf::RectangleShape body;
    sf::Vector2f velocity;
    float gravity_ = .3;

    //Constructor
    Player(int width, int height, int xinitPos, int yinitPos, sf::Color a)
    {
        body.setSize(sf::Vector2f(width, height));
        body.setPosition(xinitPos, yinitPos);
        body.setFillColor(a);
    }

    void moveCharacter(int xPos, int yPos)
    {
        body.move(xPos, yPos);
    }

    void setCharacterPosition(int xPos, int yPos)
    {
        body.setPosition(xPos, yPos);
    }

    //Parameter takes in the height at wich the invisible plane lies.
    void gravity(int height_of_plane)
    {
        if (body.getPosition().y >= height_of_plane)
        {
            body.setPosition(body.getPosition().x, height_of_plane);
            velocity.y = 0;
        }
        else if (body.getPosition().y <= height_of_plane)
        {
            body.move(velocity);
            velocity.y += gravity_;
        }
    }
};

int main()
{
    sf::RenderWindow window(sf::VideoMode(width, height), "In Development");
    window.setFramerateLimit(70);
    window.setVerticalSyncEnabled(true);

    Player character(40, 40, width / 2, height / 2, sf::Color::Black);

    sf::Event event;
    while (window.isOpen())
    {
        while (window.pollEvent(event))
        {
            if (event.type == sf::Event::Closed)
                window.close();

            if (sf::Keyboard::isKeyPressed(sf::Keyboard::Right))
            {
                character.moveCharacter(2, 0);
            }
            else if (sf::Keyboard::isKeyPressed(sf::Keyboard::Left))
            {
                character.moveCharacter(-2, 0);
            }
            else if (sf::Keyboard::isKeyPressed(sf::Keyboard::Up))
            {
                character.moveCharacter(0, -2);
            }
            else if (sf::Keyboard::isKeyPressed(sf::Keyboard::Down))
            {
                character.moveCharacter(0, 2);
            }
        }

        character.gravity(500);

        window.clear(sf::Color::White); //Clear

        window.draw(character.body);

        window.display(); //Display
    }

    int pause; cin >> pause; //Pause the program
    return 0;
}