分配
將字串分配給不同的字串型別以及執行時環境對它們的行為方式。在適用的情況下,簡要描述了記憶體分配,引用計數,對字元的索引訪問和編譯器錯誤。
var
SS5: string[5]; {a shortstring of 5 chars + 1 length byte, no trailing `0`}
WS: Widestring; {managed pointer, with a bit of compiler support}
AS: ansistring; {ansistring with the default codepage of the system}
US: unicodestring; {default string type}
U8: UTF8string;//same as AnsiString(65001)
A1251: ansistring(1251); {ansistring with codepage 1251: Cryllic set}
RB: RawbyteString; {ansistring with codepage 0: no conversion set}
begin
SS5:= 'test'; {S[0] = Length(SS254) = 4, S[1] = 't'...S[5] = undefined}
SS5:= 'test1'; {S[0] = 5, S[5] = '1', S[6] is out of bounds}
SS5:= 'test12'; {compile time error}
WS:= 'test'; {WS now points to a constant unicodestring hard compiled into the data segment}
US:= 'test'+IntToStr(1); {New unicode string is created with reference count = 1}
WS:= US; {SysAllocateStr with datacopied to dest, US refcount = 1 !}
AS:= US; {the UTF16 in US is converted to "extended" ascii taking into account the codepage in AS possibly losing data in the process}
U8:= US; {safe copy of US to U8, all data is converted from UTF16 into UTF8}
RB:= US; {RB = 'test1'#0 i.e. conversion into RawByteString uses system default codepage}
A1251:= RB; {no conversion takes place, only reference copied. Ref count incremented }