Variable parameter

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Variable parameter (or Reference Parameter) is input and output parameter meaning it can be used for passing a value to a function or a procedure as well as to get back a value from function or procedure. It indicated by the use of the keyword var in front of the formal parameter.

Variable parameter given a new nickname. The method refers to the same variable and changes made will affect the actual variable.


XOR swap

<delphi>

 procedure XorSwap(  var i,j:integer );
 begin
   i := i xor j ;
   j := i xor j ;
   i := i xor j ;
 end;

</delphi>

OrderSmallBig

<delphi>

 procedure OrderSmallBig( var a,b:integer );
 begin
   if a > b then XorSwap( a, b );
 end; 

</delphi>

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