\ Binary search
var a{10},i;

procedure search(key);
  var low,high,mid,res;
  begin
    low:=0;
    high:=9;
    res:=-1;
    while low[high do
      begin
        mid:=(low+high)/2;
        if a{mid}<key then
          low:=mid+1
        else if a{mid}>key then
          high:=mid-1
        else
          begin
            res:=mid;
            high:=-1
          end
      end;
    out:=res \ print subscript of slot
  end;

begin
  \ Load array
  i:=0;
  while i<10 do
    begin
      a{i}:=10*i;
      i:=i+1
    end;
  \ Test with fixed set of cases
  i:=-5;
  while i<100 do
    begin
      call search(i);
      i:=i+5
    end;
  i:=in;
  \ Test with user-provided cases
  while i#(-999999) do
    begin
      call search(i);
      i:=in
    end
end.