SDL delete an image and replace it with the new one

I've started SDL just a few days ago and I'm having a problem

I tried to erase an image from the screen and replace it with the new one

here is my logic :

1. load image
2. apply surface, then dela开发者_StackOverflow中文版y for 1s
3. free old image surface (SDL_FreeSurface())
4. load new image
5. apply surface

The problem is the image is still there. (it didn't get erased, just stacked with the new image)

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The screen doesn't work like you think it does. You cannot "delete" something from a screen buffer, you can only write new things to the screen buffer. To 'erase' something you need to write the "background" over it.

Some game loops just re-write the entire screen with the background every frame.

This probably belongs over at gamedev.stackexchange.com