是“寻求" & "seekg"可互换的? [英] are "seekp" & "seekg" interchangeable?

问题描述

好吧，我刚刚注意到，通过在Microsoft Visual Studio中通过"seekp"更改位置，我隐式地还可以在处理文件时更改读取位置.

Well I just noticed that by changing the position -in microsoft visual studio- through "seekp" I implicitelly also change the read-position, when handling files.

但是我想知道这是否是便携式"行为?我可以期待阅读和阅读的位置吗?写作总是一样吗?因此:tellp& tellg总是返回相同的值吗?

I am wondering however if this is "portable" behaviour? Can I expect the position of reading & writing to be always the same? And consequently: will tellp & tellg always return the same value?

推荐答案

对于文件位置，它们是相同的.换句话说，仅维护了一个指针.

For file positions they are the same. In other words there is only one pointer maintained.

来自27.9.1.1p3:

输入序列和输入序列都保持联合文件位置 输出序列.

A joint file position is maintained for both the input sequence and the output sequence.

因此，seekg和seekp对于文件流是可互换的.但是，对于其他类型的流，情况并非如此，因为它们可能为放置和获取位置持有单独的指针.

So, seekg and seekp are interchangeable for file streams. However, this is not true for other types of streams, as they may hold separate pointers for the put and get positions.

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