So my 2D platformer inspired by Mario, but not a clone has some basic stuff more or less complete, which is a subjective term in my case cause my code is probably not bug free and probably doesn't have a very good design, but learning as much as I can

I have more or less completed the following:

• Arbitrary map parsed from file.
• Moving the character left and right.
• Jumping.
• Collision detection.
• Falling off a tile due to "gravity".

The last three actually are not implemented 100% right, so they need a lot of work too, for instance I need fixed timestep instead of variable timestep as it could and usually does cause my collision detection to fail as the player could move waaay past a tile if the frame took longer than 0.001 seconds. I need to make it so the camera(i.e screen) follows the player in the center as he moves on the map.

Also, a next logical step in my opinion would be items or entities, but neither of those do I know how to implement(not even a clue!) and not sure if they will fit into my design.

Thank you in advance!

P.S

Yes, no mistake. I am doing my game in pure C using SDL 2.0. I plan to do the switch to C++ for my next game.

Sounds like you have a pretty good idea of what to do next.

Locking the camera to the player is just a matter of offsetting everything as you draw it by your camera position

camera_x = player_x - screenwidth / 2

camera_y = player_y - screenheight / 2

then whenever you draw, subtract out the camera position

Draw(x - camera_x, y - camera_y);

Items can be implemented as collidable objects, like the bricks in a level. Instead of bouncing off the player, the items will apply their effects when collided with. So when your player touches an item, a function to apply the effect is called on the player object.

What about designs for code for holding and describing an item. And say an inventory?

For the kind of items that go into an inventory, use a container (for example, an array for fixed sized inventories) attached to a character (player or otherwise) to store the items. The description of an item can go into an item description file.