增量文件指针 [英] Increment file pointer
问题描述
嗨伙计
我有一个指向文件的指针。如果我增加指针，它会指向哪里。
我在常见问题解答中找不到问题。
提前谢谢
Deepak garg
deepak< de ********* @ rediffmail.com>潦草地写道：嗨大家
我有一个指向文件的指针。如果我增加指针，它会指向哪里。
我在常见问题解答中找不到问题。
它是未定义的。
-
/ - Joona Palaste（pa*****@cc.helsinki.fi）------------ - 芬兰-------- \
\-- http://www.helsinki.fi/~palaste ---------------------规则！ -------- /
真相就在那里，伙计！出路！
- Ashfield教授
deepak写道：
嗨伙计
我有一个指向文件的指针。如果我增加指针，它将指向何处。我在常见问题解答中找不到问题。
这是FAQ 4.4，它似乎不在网上版本中。在那个
答案中，Steve Summit说C中的指针算法总是
自动按照指向的对象的大小缩放，这是一个
非常好的方式。
很容易犯错误，认为所谓的文件指针
指向文件中的某个位置，这样增加它会使它指向下一个位置，但是这样的想法是有缺陷的。文件指针
指向FILE对象，它是FILE对象包含有关正在读取，写入或更新的流的信息
，例如（例如）a
当前位置指示器。
++ fp;通常是在寻找麻烦。我可以想一想它可能有用的情况，但它们并不常见。
递增fp的例子：
FILE OutputArray [12 + 1] = {0};
FILE * fp = NULL;
if（OK == OpenAllMyFiles（ OutputArray，
sizeof OutputArray / sizeof OutputArray [0]） - 1）
{
for（fp = OutputArray; fp！= NULL; fp ++）
{
DoSomethingWith（data，fp）;
}
}
-
Richard Heathfield： bi****@eton.powernet .co.uk
Usenet是一个奇怪的地方。 - Dennis M Ritchie，1999年7月29日。
C FAQ： http://www.eskimo.com/~scs/C-faq/top.html
K& R答案，C书等：< a rel =nofollowhref =http://users.powernet.co.uk/etontarget =_ blank> http://users.powernet.co.uk/eton
文章< 7c ************************** @ posting.google.com> ，
de*********@rediffmail.com （deepak）写道：
嗨伙计们
我有一个指向文件的指针。如果我增加指针，它会指向哪里。
我在常见问题解答中找不到问题。
过了文件末尾。
hi folks
I have a pointer to a file. If i increment the pointer, where will it point.
I could not find the problem in the FAQs.
Thanks in advance
Deepak garg
deepak <de*********@rediffmail.com> scribbled the following:hi folks I have a pointer to a file. If i increment the pointer, where will it point.
I could not find the problem in the FAQs.
It''s undefined.
--
/-- Joona Palaste (pa*****@cc.helsinki.fi) ------------- Finland --------\
\-- http://www.helsinki.fi/~palaste --------------------- rules! --------/
"The truth is out there, man! Way out there!"
- Professor Ashfield
deepak wrote:
hi folks
I have a pointer to a file. If i increment the pointer, where will it
point. I could not find the problem in the FAQs.
It''s FAQ 4.4, which doesn''t appear to be in the online version. In that
answer, Steve Summit says that "pointer arithmetic in C is always
automatically scaled by the size of the objects pointed to", which is a
very good way to put it.
It is easy to make the mistake of thinking that a so-called "file pointer"
points to a position in the file, so that incrementing it would make it
point to the next position, but such thinking is flawed. A file pointer
points to a FILE object, and it is the FILE object contains information
about the stream being read, written or updated, such as (for example) a
current position indicator.
++fp; is normally asking for trouble. I can think of circumstances where it
might be useful, but they are not overly common.
Example of incrementing fp:
FILE OutputArray[12 + 1] = {0};
FILE *fp = NULL;
if(OK == OpenAllMyFiles(OutputArray,
sizeof OutputArray / sizeof OutputArray[0]) - 1)
{
for(fp = OutputArray; fp != NULL; fp++)
{
DoSomethingWith(data, fp);
}
}
--
Richard Heathfield : bi****@eton.powernet.co.uk
"Usenet is a strange place." - Dennis M Ritchie, 29 July 1999.
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html
K&R answers, C books, etc: http://users.powernet.co.uk/eton
In article <7c**************************@posting.google.com >,
de*********@rediffmail.com (deepak) wrote:
hi folks
I have a pointer to a file. If i increment the pointer, where will it point.
I could not find the problem in the FAQs.
Past the end of the file.
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