How can I print the frames per second on my window's title in glut?

I tried this:

    char window_title[20]; 
    sprintf(window_title, "%f", fps);

    glutCreateWindow(window_title);

And isn't updating (remains 0) I checked fps 开发者_如何学编程being updated via printf.

How can I update the title?

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Call glutSetWindowTitle with the fps after you compute it.