BBC BASIC Programmers' Reference

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=====Passing arrays to SUBs and FUNCTIONs=====

//by Richard Russell, March 2014//\\ \\  LB Booster provides the capability of passing an entire array as a parameter to a SUB or a FUNCTION. Here is a simple example:\\ 
<code lb>
      one(5) = 123
      call test one()
      end

  sub test two()
      print two(5)
  end sub
</code>
To demonstrate that the array **two()** is genuinely 'local' to the SUB:\\ 
<code lb>
      one(5) = 123
      two(5) = 456
      call test one()
      print two(5)
      end

  sub test two()
      print two(5)
  end sub
</code>
Arrays are automatically passed 'by reference' (you don't need to specify BYREF):\\ 
<code lb>
      one(5) = 123
      two(5) = 456
      call test one()
      print two(5)
      print one(5)
      end

  sub test two()
      print two(5)
      two(5) = 789
  end sub
</code>
But you **must** use BYREF if you want to REDIM the array inside the SUB (requires LBB v2.53 or later):\\ 
<code lb>
      one(5) = 123
      two(5) = 456
      call test one()
      print two(5)
      print one(15)
      end

  sub test byref two()
      print two(5)
      redim two(15)
      two(15) = 789
  end sub
</code>
Of course you can use a FUNCTION instead of a SUB:\\ 
<code lb>
      one(5) = 123
      two(5) = 456
      print test(one())
      print two(5)
      print one(5)
      end

  function test(two())
      test = two(5)
      two(5) = 789
  end function
</code>