TStream.Position与TStream.Seek的比较 [英] TStream.Position compared to TStream.Seek

问题描述

要在TStream类中移动当前字节指针，我们可以使用位置属性（例如MyStream.Position：= 0）或使用Seek方法（例如MyStream.Seek（0，soFromBeginning）。问题是，哪个是

To move the "current byte" pointer in TStream class we can use property Position (e.g. MyStream.Position := 0) or using Seek method (e.g. MyStream.Seek(0, soFromBeginning). The question is, which one is more efficient (aka faster)? (I don't have the source, so I could not check it myself).

到目前为止，我一直使用Seek来定位

So far I always use Seek in positioning that said pointer.

推荐答案

由于 TStream.Seek 是重载的函数，处理32或64位值，它取决于当前的流实现，这可能是更好的选择。

As TStream.Seek is an overloaded function handling 32-Bit or 64-Bit values, it depends on the current stream implementation, which might be the better choice.

例如 TCustomMemoryStream 实现32位版本的 Seek（）。在该流上设置 Position 时，首先调用64位版本，然后在调用32位版本时将值转换为Longint（这可能会随Delphi的64位版本而改变！）

For instance TCustomMemoryStream implements the 32-Bit version of Seek(). When you set Position on that stream this will first call the 64-Bit version, which casts the value to a Longint while calling the 32-Bit version. (This will probably change with a 64-Bit version of Delphi!)

另一方面，有一个 THandleStream 实现nts Seek（）的64位版本。当您使用32位值调用 Seek（）时，您会遇到一种非常讨厌的机制，称为64位版本。

On the other hand a THandleStream implements the 64-Bit version of Seek(). When you call Seek() with a 32-Bit value you end up in a quite nasty mechanism calling the 64-Bit version.

我个人的建议是设置 Position 。至少将来它将是更好的选择。

My personal advice would be to set Position. At least it will be the better choice in the future.

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