Delphi XE2数据集字段类型TStringField不支持Unicode？ [英] Delphi XE2 Dataset field type TStringField does not support Unicode?

问题描述

在Delphi XE2中，我一直在浏览TDataset类及其字符串字段，并注意到AsWideString返回一种UnicodeString类型。然而，它从函数TField.AsString：String中获取值，该值依次调用TFIeld.AsAnsiString：AnsiString。因此任何unicode字符都会丢失？此外，传递给TDataset.GetFieldData的缓冲区被声明为一个AnsiChar的数组。

我正确理解这一点？

解决方案

不，您应该检查 TWideStringField 类，用于Unicode字段和 TStringField 类这是非Unicode字符串。 TField 只是一个基础类， TField.GetAsWideString 是一种具有后退实现的虚拟方法，该方法被Unicode感知的后代所覆盖。 >

I've been looking through the TDataset class and its string fields, in Delphi XE2 and noticed that AsWideString returns a type of UnicodeString. However it gets the value from the function TField.AsString: String which in turn calls TFIeld.AsAnsiString:AnsiString. Therefore any unicode characters would be lost? Also the buffer which is passed to TDataset.GetFieldData is declared as an array of AnsiChar.

Am I understanding this correctly?

解决方案

No, you should be examining the TWideStringField class which is for Unicode fields and the TStringField class which is for non-Unicode strings. TField is just a base class and TField.GetAsWideString is a virtual method with a fall back implementation that is overridden by descendants that are Unicode aware.

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