要用C语言绘制曲线，可以使用图形库如OpenGL或者SDL来实现。下面是一个简单的使用SDL绘制曲线的示例代码：
#include <SDL.h>int main(int argc, char *argv[]) { SDL_Init(SDL_INIT_VIDEO); SDL_Window *window = SDL_CreateWindow("Curve Drawing", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 800, 600, 0); SDL_Renderer *renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED); SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255); SDL_RenderClear(renderer); SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255); int x1 = 100, y1 = 100; int x2 = 700, y2 = 500; int steps = 100; for (int i = 0; i < steps; i++) { float t = (float)i / steps; int x = x1 + t * (x2 - x1); int y = y1 + t * (y2 - y1); SDL_RenderDrawPoint(renderer, x, y); } SDL_RenderPresent(renderer); bool quit = false; SDL_Event event; while (!quit) { while (SDL_PollEvent(&event)) { if (event.type == SDL_QUIT) { quit = true; } } } SDL_DestroyRenderer(renderer); SDL_DestroyWindow(window); SDL_Quit(); return 0;}这个示例代码使用SDL库来创建窗口和渲染器，然后绘制一条直线。你可以修改x1、y1、x2、y2来绘制不同的曲线，也可以修改steps来控制曲线的平滑度。整个绘制过程是通过在起点和终点之间插值的方式来实现的。最后，通过处理SDL的事件循环来保持窗口显示，直到用户关闭窗口。
