E2033: Types of actual and formal var parameters must be identical (Delphi)

For a variable parameter, the actual argument must be of the exact type of the formal parameter.

program Produce;

procedure SwapBytes(var B1, B2: Byte);
var
  Temp: Byte;
begin
  Temp := B1; B1 := B2; B2 := Temp;
end;

var
  C1, C2: 0..255;     (*Similar to a byte, but NOT identical*)
begin
  SwapBytes(C1,C2);   (*<-- Error message here*)
end.

Arguments C1 and C2 are not acceptable to SwapBytes, although they have the exact memory representation and range that a Byte has.

Copy Code

program Solve;

procedure SwapBytes(var B1, B2: Byte);
var
  Temp: Byte;
begin
  Temp := B1; B1 := B2; B2 := Temp;
end;

var
  C1, C2: Byte;
begin
  SwapBytes(C1,C2);   (*<-- No error message here*)
end.

So you actually have to declare C1 and C2 as Bytes to make this example compile.

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