在SDL中，旋转SDL_Surface可能会导致错误的结果，因为旋转操作会改变原始图像的大小和像素布局。为了解决这个问题，可以使用旋转函数SDL_RenderCopyEx()来在渲染器上绘制旋转的纹理。下面是一个示例代码：

#include 

int main(int argc, char* argv[]) {
    SDL_Init(SDL_INIT_VIDEO);

    SDL_Window* window = SDL_CreateWindow("SDL Rotation Example", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 640, 480, SDL_WINDOW_SHOWN);
    SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);

    SDL_Surface* imageSurface = SDL_LoadBMP("example.bmp");
    SDL_Texture* texture = SDL_CreateTextureFromSurface(renderer, imageSurface);

    int angle = 45; // 旋转角度

    int width = imageSurface->w;
    int height = imageSurface->h;

    SDL_Rect sourceRect = {0, 0, width, height};
    SDL_Rect destinationRect = {0, 0, width, height};
    SDL_Point center = {width/2, height/2}; // 旋转中心点

    SDL_RenderClear(renderer);
    SDL_RenderCopyEx(renderer, texture, &sourceRect, &destinationRect, angle, ¢er, SDL_FLIP_NONE);
    SDL_RenderPresent(renderer);

    bool quit = false;
    SDL_Event event;
    while (!quit) {
        while (SDL_PollEvent(&event) != 0) {
            if (event.type == SDL_QUIT) {
                quit = true;
            }
        }
    }

    SDL_DestroyTexture(texture);
    SDL_FreeSurface(imageSurface);
    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    SDL_Quit();

    return 0;
}

上述代码使用SDL_CreateTextureFromSurface()函数将SDL_Surface转换为纹理，然后使用SDL_RenderCopyEx()函数在渲染器上绘制旋转的纹理。通过指定旋转角度、源矩形、目标矩形和旋转中心点，可以实现旋转效果。