Learn To Code: Swap Integers Custom Function

[kevin]

    Learn To Code: Swap Integers Custom Function

     There's any number of ways to SWAP (exchange) the contents of two integers variables, Normally I would copy one of the variables into a third TEMP variable then proceed to copy the values around, but you can do it without the added temp variable also.  

     Here's a method that just uses additions and subtractions

PlayBASIC Code: [Select]

      // Declare our two pair of variable for our swap test
      a=-100
      b=50

      //  Display the current values in both A and B variables      
      print "Original Values:"
      print "A="+Str$(A)
      print "B="+Str$(A)
      print ""


      //  Call our SWAP INTEGERS Function
      A,B=SwapInts(A,B)
      
      
      //  Display the new values in both A and B variables      
      print "Value After Swap"
      print "A="+Str$(A)
      print "B="+Str$(A)
      print ""


      //  Show the graphics screen to the user and wait for a KEY
      //  before ENDING      
      Sync
      waitkey
      END
      
      
      
   // -------------------------------------------------
   //  Swap Integers Function
   // -------------------------------------------------

Function SwapInts(X,Y)

      // store the sum of both input values in X   
      X=X+Y
      
      // To compute NEW Y we subtract OLD Y from the X+Y sum
      Y=X-Y
      
      // To compute NEW X we subtract SWAPPED Y from the X+Y sum
      X=X-Y

      //  restore this pair of values back to the caller   
EndFunction X,Y

   Note: PlayBASIC has a built in SWAP function