Is this code safe? function Some(const Str : AnsiString); var arr : TBytes …

[WayBack] Is this code safe? function Some(const Str : AnsiString); var arr : TBytes absolute Str; begin fSomeMethodWithTBytesParam(arr); <- arr is properly c… – Jacek Laskowski – Google+

Such a seemingly simple question:

Is this code safe?

procedure Some(const Str : AnsiString); 
var arr : TBytes absolute Str; 
begin
  fSomeMethodWithTBytesParam(arr); // <- arr is properly casted to string bytes? 
end;

Such a wealth of information in the comments:

• No it is not, except for the nil-pointer case
• The compiler has for instance an implicit length prefix
• In 32-bit mode, the Length prefix of strings and dynamic arrays are both 32-bits
• In 64-bit mode, the Length prefix of strings is 32-bits, but the one for dynamic arrays is 64-bits
• use BytesOf to transform from characters to bytes
• do not store binary data into strings of single-byte character sets

–jeroen