I studied Computer Science in Germany, and I didn't use a single book during my entire bachelor. The way it worked was professors always put the slides from their lectures online, so we could reference them as sources. Sometimes, additional references or texts were available online.

In addition to lectures, we had weekly classes where we applied the concepts from the lecture in practice. Exercises for these classes were also available online.

All of this material was free for students, and created by the professors and instructors specifically for the course.