The void type, in several programming languages derived from C and Algol68, is the type for the result of a function that returns normally, but does not provide a result value to its caller. Usually such functions are called for their side effects, such as performing some task or writing to their output parameters. The usage of the void type in such context is comparable to that of the syntactic constructs which define subroutines in Visual Basic and procedures in Pascal. It is also similar to the unit type used in functional programming languages and type theory; however, there are some differences in allowable usage, in that the void type is taken to be an empty type with no values. See Unit type#In programming languages for a comparison.
C and C++ also support the pointer to void type (specified as void *), but this is an unrelated notion. Variables of this type are pointers to data of an unspecified type, so in this context (but not the others) void acts as a universal or top type. A program can convert a pointer to any type of data (except a function pointer) to a pointer to void and back to the original type without losing information, which makes these pointers useful for polymorphic functions.
Read more about Void Type: In C and C++
Famous quotes containing the words void and/or type:
“Aesop, that great man, saw his master making water as he walked. “What!” he said, “Must we void ourselves as we run?” Use our time as best we may, yet a great part of it will still be idly and ill spent.”
—Michel de Montaigne (1533–1592)
“It took six weeks of debate in the Senate to get the Arms Embargo Law repealed—and we face other delays during the present session because most of the Members of the Congress are thinking in terms of next Autumn’s election. However, that is one of the prices that we who live in democracies have to pay. It is, however, worth paying, if all of us can avoid the type of government under which the unfortunate population of Germany and Russia must exist.”
—Franklin D. Roosevelt (1882–1945)