Question

procedure Example is
                X: Integer;

        procedure First is
        begin
                Put(X);                 -- Print X
                New_Line;               -- Print a newline character
        end First;

        procedure Second is
                X: integer;

                procedure Third is
                        X: Integer;
                begin -- Third
                        x := 99;
                        First;
                end Third;

        begin -- Second
                x := 88;
                Third;
        end Second;

begin -- Example 
        x := 77;
        First;
        Second;
end Example;

a) What will be printed by this program if we assume static scope?
b) What will be printed by this program if we assume dynamic scope?

Answer 1

static scope:

In this approach the value assigned at program begin and the value remains same in entire program:

begin -- Example 
        x := 77;  // The value of x is 77 and it remains same through out the program
        First;

   procedure First is
        begin
                Put(X);                 -- Print 77
                New_Line;               -- Print a newline character
        end First;


        Second;

 procedure Second is

 begin -- Second
                x := 88; -- The value remains same 77
                Third;

                procedure Third is
                        X: Integer;
                begin -- Third
                        x := 99;  -- The value remains same 77

 First;

   procedure First is
        begin
                Put(X);                 -- Print 77
                New_Line;               -- Print a newline character
        end First;

                end Third;

        end Second;
end Example;

Output:

77

77

Dynamic scope:

In this approach the value changed with respect to called functions.

begin -- Example 
        x := 77;  // The value of x is 77 
        First;

   procedure First is
        begin
                Put(X);                 -- Print 77
                New_Line;               -- Print a newline character
        end First;


        Second;

 procedure Second is

 begin -- Second
                x := 88; -- The value of x is 88
                Third;

                procedure Third is
                        X: Integer;
                begin -- Third
                        x := 99;  -- The value of x is 99

 First;

   procedure First is
        begin
                Put(X);                 -- Print 99
                New_Line;               -- Print a newline character
        end First;

                end Third;

        end Second;
end Example;

Output:

77

99