High-level Programming Language (Pascal)

Sequential Structure

• execution of a sequence of statements in the order in which they appear so that each statement is executed exactly once
• the arrows in the diagram, called flow lines, indicate the order in which the statements are executed

  

• in a Pascal program, a sequential structure is implemented by a compound statement whose syntax is as follows :

• compound statement is a sequence of statements placed within the reserved words begin and end

  begin
  　<statement_1>;
  　<statement_2>;
  　　　　… ;
  　<statement_n>
  end ;

• for example,
  
   

begin
　write ('Enter two numbers : ');
　readln (Number1, Number2);
　Sum := Number1+Number2;
　writeln ('Sum = ', Sum)
end;

• first displays a prompt to the user and then reads two numbers; next, it calculates their sum; and finally, it displays the result