两个数交换

program swap;
var
　　a, b, c : real;
begin
　　read(a, b);
　　writeln('original:', chr(10), 'a = ', a:7:2, chr(9), 'b = ', b:7:2);
　　c := a;
　　a := b;
　　b := c;
　　writeln('swapped:', chr(10), 'a = ', a:7:2, chr(9), 'b = ', b:7:2);
end.

===== 或者 =====

program swap;
var
　　a, b: real;
begin
　　writeln('please input two numbers: ');
　　read(a, b);
　　writeln('original:', chr(10), 'a = ', a:7:2, chr(9), 'b = ', b:7:2);
　　a := a+b;
　　b := a-b;
　　a := a-b;
　　writeln('swapped:', chr(10), 'a = ', a:7:2, chr(9), 'b = ', b:7:2);
end.