{{fbdoc item="title" value="User Defined Types"}}----
Custom types.

{{fbdoc item="section" value="Overview"}}
	//User-Defined Types// are special kinds of [[ProPgVariables|variables]] which can be created by the programmer.  A User-Defined Type (UDT) is really just a container that contains a bunch of other variables, like an [[ProPgArrays|array]], but unlike arrays, UDTs can hold //different// variable types (whereas arrays always hold many variables of the //same// type).  In fact, UDTs can even have [[ProPgProcedures|procedures]] inside of them!

{{fbdoc item="section" value="Members"}}
	The different variables and/or procedures stored inside a UDT are called "members", or more generally, items.  Members can be variables of just about any type, including numerical types, strings, [[ProPgPointers|pointers]], [[KeyPgEnum|enums]], and even arrays.  Variables are created in UDTs much the same way variables are created 	normally, except that the Dim keyword is optional.  UDT members are accessed via the [[KeyPgOpMemberAccess|. operator]], so for example if you created a variable called someVar in a UDT you would access it with the name of the UDT variable followed by ".someVar".  Here is an example:

{{fbdoc item="filename" value="examples/manual/proguide/udt/simple.bas"}}%%(freebasic)
'Define a UDT called myType, with an Integer member named someVar
Type myType
  As Integer someVar
End Type

'Create a variable of that type
Dim myUDT As myType

'Set the member someVar to 23, then display its contents on the screen
myUDT.someVar = 23
Print myUDT.someVar
%%

	Notice that the [[KeyPgType|Type...End Type]] does not actually create a variable of that type, it only defines what variables of that type contain.  You must create a variable of that type to actually use it!

{{fbdoc item="section" value="UDT Pointers"}}
	UDT Pointers are, as the name implies, pointers to UDTs.  They are created like regular pointers, but there is a special way to use them.  To access the member of a UDT pointed to by a pointer, you use the [[KeyPgOpPtrMemberAccess|-> operator]].  For example, if myUDTPtr is a pointer to a UDT which has a member someVar, you would access the member as myUDTPtr->someVar, which is a much cleaner shorthand for the equally valid (*myUDTPtr).someVar.

{{fbdoc item="filename" value="examples/manual/proguide/udt/ptr-access.bas"}}%%(freebasic)
Type rect
	x As Integer
	y As Integer
End Type

Dim r As rect
Dim rp As rect Pointer = @r

rp->x = 4
rp->y = 2

Print "x = " & rp->x & ", y = " & rp->y
Sleep
%%

{{fbdoc item="see"}}
	- [[ProPgTypeAliases|Type Aliases]]
	- [[KeyPgTypeTemp|Temporary Types]]
	- [[ProPgCtorsDtors|Constructors and Destructors]]
	- [[ProPgMemberProcedures|Member Procedures]]
	- [[ProPgMemberAccessRights|Member Access Rights]]
	- [[ProPgOperatorOverloading|Operator Overloading]]


{{fbdoc item="back" value="CatPgProgrammer|Programmer's Guide"}}