I know that it is possible to define a lot of different norms on continuous function spaces like $l_p$ norms. However, I was wondering if it is possible to define a norm on the function space consisting of all functions from $\Bbb R$ to $\Bbb R$. I have tried a few examples and none of them managed to fulfill all the requirements of being a norm, so maybe it is actually impossible to define such a norm.
Edit: I know such a norm exists but I wondered if it has a “simple” representation, meaning given a function I can actually calculate its norm and not just know “it exists”.