Advanced Ragdoll/AI Physics

[austinn2003]

If you've played Grand Theft Auto 4 or 5, you will know that the animations are very synced to eachother. That's due to a thing called the Euphoria Engine. If your unsure of what the Euphoria Engine is, here is a video:

[video=youtube;wKLaMN9dnjQ]https://www.youtube.com/watch?v=wKLaMN9dnjQ[/video]

Now, I want to recreate that for the player, but it will be a simple version for my game. But I can't seem to get a single arm to go back and forth for walking. I'm also using SDL2 to make this.

Here is my code:

while (!Close && e->type != SDL_QUIT)
	{
		SDL_PollEvent(e);

		SDL_RenderClear(_renderer);

		SDL_RenderCopy(_renderer, _bgimg, NULL, &bg_rect);

		SDL_RenderCopy(_renderer, _headimg, NULL, &head_rect);

		SDL_RenderCopy(_renderer, _bodyimg, NULL, &body_rect);

		if (e->type == SDL_KEYDOWN)
		{
			if (e->key.keysym.sym == SDLK_a)
			{
				body_rect.x = body_rect.x - 3;
				arm_rect.x = body_rect.x;
				head_rect.x = body_rect.x;
				leg_rect.x = body_rect.x;
                                ++armangle;
				if (armangle >= 90)
				{
					--armangle;
				}
			}
			if (e->key.keysym.sym == SDLK_d)
			{
				body_rect.x = body_rect.x + 3;
				arm_rect.x = body_rect.x;
				head_rect.x = body_rect.x;
				leg_rect.x = body_rect.x;
			}
		}
		SDL_RenderCopyEx(_renderer, _armimg, NULL, &arm_rect, armangle, NULL, flip);

		SDL_RenderCopyEx(_renderer, _legimg, NULL, &leg_rect, legangle, NULL, flip);


		SDL_RenderPresent(_renderer);

		Mix_PlayMusic(menumusic, -1);
	}

If you can paste in a edited version or just giving me an idea to make it work that would be great.