In Java, it would look like this:
class Foo
{
float[] array;
}
Foo instance = new Foo();
instance.array = new float[10];
You can just use a pointer:
float *array;
// Allocate 10 floats -- always remember to multiple by the object size
// when calling malloc
array = (float *)malloc(10 * sizeof(float));
...
// Deallocate array -- don't forget to do this when you're done with your object
free(array);
If you're using Objective-C++, you could instead do:
float *array;
array = new float[10];
...
delete [] array;