SFML Collisions never register in my system - c++

Question

Trying to make a collision system in sfml for the first time in SFML without using a tutorial, using a array-based thing like so:
bool moright, moleft, moup, xcollision, ycollision;
float xvel, yvel;
int position, predictx, predicty, cm, arraynum;
class playerClass{
public:
playerClass(){
}
void update()
{
if (moright == true){
xvel = 2;}
if (moleft == true){
xvel = -2;}
if (!(moright || moleft)){
if (xvel < 0)
xvel = 0;
if (xvel > 0)
xvel = 0;}
}
};
int main()
{
playerClass playerObject;
// Create the main window
RenderWindow window(VideoMode(1080, 720), "SFML window");
// Load a sprite to display
Texture texture;
if (!texture.loadFromFile("gsquare100x100.png"))
return EXIT_FAILURE;
Sprite sprite(texture);
Sprite floor(texture);
Sprite wall(texture);
floor.setPosition(Vector2f(0.f, 498.f));
wall.setPosition(Vector2f(598.f,0.f));
floor.setColor(Color(0, 255, 0));
floor.setScale(12.f, 12.f);
wall.setScale(12.f, 12.f);
wall.setColor(Color(0, 0, 255));
int collisions[2][4]{
{0, 400, 500, 600},
};
// Start the game loop
while (window.isOpen())
{
Vector2f position = sprite.getPosition();
cout << position.y << endl;
predictx = position.x + xvel;
predicty = position.y + yvel;
yvel = 1;
for (arraynum = 0; arraynum < 2; arraynum++){
if ((predictx > collisions[arraynum][0])&&(predictx < collisions[arraynum][1])&&(predicty > collisions[arraynum][2])&&(predicty < collisions[arraynum][3])){
if ((position.y > collisions[arraynum][3])||(position.y < collisions[arraynum][2])){
xcollision = true;}
if ((position.x > collisions[arraynum][1])||(position.x < collisions[arraynum][0])){
ycollision = true;}
}
}
if (xcollision == true)
xvel = 0;
xcollision = false;
if (ycollision == true)
yvel = 0;
ycollision = false;
sprite.move(sf::Vector2f(0.f+xvel, 0.f+yvel));
// Process events
sf::Event event;
while (window.pollEvent(event))
{
if (event.type == Event::KeyPressed)
{if (event.key.code == Keyboard::D)
moright = true;
if (event.key.code == Keyboard::A)
moleft = true;}
if (event.type == Event::KeyReleased)
{if (event.key.code == Keyboard::D)
moright = false;
if (event.key.code == Keyboard::A)
moleft = false;}
playerObject.update();
}
However the collision never registers, removing the bit that checks from which direction the sprite is moving in from doesn't help.
Very new to c++ so apologies if this is a stupid question and for my likely overly elaborate collision system.

Answer 1

I've written simple collisions with SFML before, and here's my advice to you: make your code as readable as possible! Things are going to get more complicated, and you need to have a system is reusable and easy to understand.
I've read your code but I don't understand why you've used an array. I assume you're trying to check if a smaller rectangle sprite is about to exit the collisions array?
For this purpose I suggest using a FloatRect object. It has useful functions like .contains() and .intersects() that you might need in the future. One downside it that is has top and left only, and to make it more and short, we'll define a simple struct to handle that part for us, as well as work for rectangular sprites as well.
I've left comments that explain the code, but haven't tested it personally. You can do that and integrate what you've learned into your project. Good luck
#include <SFML/Graphics.hpp>
#include <SFML/System.hpp>
using namespace sf;
//using a struct is not necessarily faster. BUT it does give your code more readability and is reusable for future needs
//this struct just stores a floatRect of the given sprite/Floatrecct, defining some useful functions allowing for shorter code and more readability
struct rectangularShape
{
FloatRect containingRectangle;
//constructor with sprite input
rectangularShape(Sprite sprite)
{
this -> containingRectangle = FloatRect(Vector2f(sprite.getGlobalBounds().left, sprite.getGlobalBounds().top),
Vector2f(sprite.getGlobalBounds().left + sprite.getGlobalBounds().width,sprite.getGlobalBounds().top + sprite.getGlobalBounds().height));
}
//constructor with floatrect
rectangularShape(FloatRect rect)
{
this -> containingRectangle = rect;
}
//any useful functions for rectangular shapes-- you could add more if you want
float getTop() {return containingRectangle.top;}
float getbottom() {return containingRectangle.top + containingRectangle.height;}
float getleft() {return containingRectangle.left;}
float getright() {return containingRectangle.left + containingRectangle.width;}
};
//note the use of a FloatRect instead of the arrays you were using, this just makes it easier to understand
FloatRect inclusionArea(TopLeftVector, BottomRightVector);
Sprite sprite(texture);
//declare rectangularShapes, here we check if smallRectangle is exiting it's container
rectangularShape containingRectangle(inclusionArea);
rectangularShape smallRectangle(sprite);
//alternatively you can use the sprite's next position:
/*
spriteCopy = sprite;
spriteCopy.move(deltaTime * Vector2f(xSpeed, ySpeed));
rectangularShape smallRectangle(spriteCopy);
*/
//do the check:
if (smallRectangle.getTop() < containingRectangle.getTop() or smallRectangle.getBottom() > containingRectangle.getBottom())
//exiting in Y axis
//do something;
;
if (smallRectangle.getLeft() < containingRectangle.getLeft() or smallRectangle.getRight() > containingRectangle.getRight())
//exiting in X axis
//do something;
;

Answer 2

I can't comment due to low reputation.
From the code presented, it's seems like you never set xcollision or ycollision to true anywhere.