UStack.pas

Unit UStack;

interface

const
    size = 200;
type
    TInfo = char;
    Stack = object
    private
        TopPtr: integer;
        S: array [1..size] of TInfo;
    public
        procedure Init;
        procedure Push(X: TInfo);
        function Pop: TInfo;
        function Top: TInfo;
        function IsFull: boolean;
        function isEmpty: boolean;
    end;

implementation

procedure Stack.Init;
begin
    TopPtr:= 0;
end;

procedure Stack.Push(X: TInfo);
begin
    TopPtr:= TopPtr + 1;
    S[TopPtr]:= X;
end;

function Stack.Pop: TInfo;
begin
    Pop:= S[TopPtr];
    TopPtr:= TopPtr - 1;
end;

function Stack.Top: TInfo;
begin
    Top:= S[TopPtr];
end;

function Stack.isFull: boolean;
begin
    isFull:= TopPtr = size;
end;

function Stack.isEmpty: boolean;
begin
    isEmpty:= TopPtr = 0;
end;

end.