在freeBASIC中创建类类型时遇到一些问题

Question

在互联网上读到我们将FreeBASIC称为面向对象的语言，在这种语言中，可以创建原语类并将其用作真正的对象。我见过一些例子，但我不能理解它们是如何工作的，因为当我去编译时，总是会给我一些错误。

这是我的代码的一个例子，我试图理解如何使用它

type MyClass
    dim mystring as string
    function myfunction()as string
        dim myout as string
        myout = "Hello your message are: " + this.mystring
        return myout
    end function

end type

dim myobject as myclass

myobject.mystring = "Im noob"
print myobject.myfunction

但这种方式行不通

Answer 1

不幸的是，FreeBASIC有一个不优雅的类管理，并且有一些限制，当你创建一个类时，你不能把函数或subs放在里面，但是你可以声明它们，然后在类型之外构建它们，下面我写了一个源代码，它展示了它是如何构造的，当你创建一个在类内部声明的函数时，它的前面必须是用点分隔的类名

'This one define  "IsEven(value)" 
'that give true or 1 if the vaule n are Even number
#define IsEven(n) ((n AND 1) = 0)



'I make a class type where inside are 2 vars and 2 functions
type Useless
    ' this is the vars as integer
    dim StartNum as integer
    dim CurrentNum as integer
    
    ' this are the functions  declared we ave to declare the function who work inside the class
    declare function EvenValue(byval value as integer)as integer
    declare function OddValue(byval value as integer)as integer
    declare function FinalValue()as string
    

end type

' After declare the function inside the type (class)  we ave to use the 
' name of type followed with the name of the function  separated by dot.
'
' inside type "declare myfunction()as integer" 
' the function can be string too or other type
'
' when close the type with "End Type"  you can make the function
' function nameclass.myfunction()as integer

function Useless.EvenValue(byval value as integer)as integer
    dim Result as integer
    Result = (value / 2)
    return Result
end function

function Useless.OddValue(byval value as integer)as integer
    dim Result as integer
    Result = ((value * 3) + 1 )
    return Result
end function

function Useless.FinalValue()as string
    'with this you can use every function, var or sub 
    'inside the class(type) 
    'watever name you used for the object
    dim OutMess as String
    OutMess = "Start value =" + str(this.StartNum) + "   ----  End value =" + str(this.CurrentNum)
    return OutMess
end function


'this are global var outside of class(type)
dim thenexit as integer = 0

'this is the object created as class
dim Calculate as Useless 

'message text and store imput inside the public integer var inside the object
print "type a number"
input Calculate.StartNum

'you can change value taked from other var from the object
Calculate.CurrentNum = Calculate.StartNum

'We use the do until cicle because we know at last we ave the one value 
do until(thenexit > 0)

if IsEven(Calculate.CurrentNum) then 
    'we use the object.function for even value
    Calculate.CurrentNum = Calculate.EvenValue(Calculate.CurrentNum)
    
else
    'we use the object.function for odd value
    Calculate.CurrentNum = Calculate.OddValue(Calculate.CurrentNum)
end if


print Calculate.CurrentNum

if Calculate.CurrentNum = 1 then 
    'and at the end we use the function with shared vars
    print Calculate.FinalValue
    thenexit = 1
end if

loop