писателя

In a sentence

• У писателя было много интересных идей.

  The writer had many interesting ideas.

  In this sentence, 'писателя' is used to indicate possession, referring to the writer's ideas, and is in the genitive case.

• Я встретил известного писателя на конференции.

  I met a famous writer at the conference.

  Here, 'писателя' is in the accusative case, showing that the writer is the direct object of the verb 'встретил' (met).

• Мы говорили о творчестве писателя.

  We talked about the writer's works.

  In this context, 'писателя' is in the genitive case, used after the preposition 'о' to indicate the topic of discussion.