Pascal - Nested Case Statements

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It is possible to have a case statement as part of the statement sequence of an outer case statement. Even if the case constants of the inner and outer case contain common values, no conflicts will arise.

Syntax:

The syntax for a nested case statement is as follows:

case (ch1) of
   'A': begin
           writeln('This A is part of outer case' );
           case(ch2) of
              'A': writeln('This A is part of inner case' );
              'B': (* case code *)
		      ...
	       end; {end of inner case}
       end; (* end of case 'A' of outer statement *)
   'B': (* case code *)
   'C': (* case code *)
   ...
end; {end of outer case}

Example:

The following program illustrates the concept.

program checknestedCase;
var
   a, b: integer;
begin
   a := 100;
   b := 200;
   case (a) of
      100: begin
              writeln('This  is part of outer statement' );
              case (b) of
                 200: writeln('This  is part of inner statement' );
              end;
           end; 
   end;
   writeln('Exact value of a is : ', a );
   writeln('Exact value of b is : ', b );
end.

When the above code is compiled and executed, it produces the following result:

This is part of outer switch
This is part of inner switch
Exact value of a is: 100
Exact value of b is: 200


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