Use of cudamalloc(). Why the double pointer?

Question

I am currently going through the tutorial examples on http://code.google.com/p/stanford-cs193g-sp2010/ to learn CUDA. The code which demostrates __global__ func

Answer 1

All CUDA API functions return an error code (or cudaSuccess if no error occured). All other parameters are passed by reference. However, in plain C you cannot have references, that's why you have to pass an address of the variable that you want the return information to be stored. Since you are returning a pointer, you need to pass a double-pointer.

Another well-known function which operates on addresses for the same reason is the scanf function. How many times have you forgotten to write this & before the variable that you want to store the value to? ;)

int i;
scanf("%d",&i);