Prepositions

[euncu]

I've to give the English examination

Why does the bolded part sounds unnatural to me? I hear it seldom. Is it OK to contract have when it is a part of objective obligation?

[Rover_KE]

Junaid has been sending mixed messages here. First he led us to believe he was setting an exam, and later that the sentences were already prescribed.

To answer your question, the bolded sentence is natural and common in informal speech.
Formally, and in writing, 'I have to give...' should be used.

Rover