procedure FillChar(var X; Count: NativeInt; Value: Integer);
Fills contiguous bytes with a specified value.
In addition, the filling character is a single-byte character. Therefore, when Buf is a UnicodeString, the code FillChar(Buf, Length(Buf), #9); fills Buf with the code point $0909, not $09. In such cases, you should use the StringOfChar routine.
Warning: This function does not perform any range checking.
Warning: This method has an untyped parameter, which can lead to memory corruption. To avoid this problem, use SizeOf to find the number of bytes appropriate to fill for the data type of the