Some questions

What does these things do? :
"(int)"
"(double)"
multiplication with "2.0f"
the function "floor(...)"
"unsigned char + [any variable]"
"(float)"
and "float [any variable]"
"(int)"
"(double)"
multiplication with "2.0f"
the function "floor(...)"
"unsigned char + [any variable]"
"(float)"
and "float [any variable]"