警告Scanf [英] Warning against Scanf
问题描述
我正在阅读O''Reilly'的'Practical C programming"本书并且它警告
反对使用scanf，建议避免完全使用它。
相反，它建议使用fgets和sscanf。但是没有提供
的解释，除了那个扫描线的结尾非常好。
非常糟糕。我在做一些数字编程时遇到过这样的问题，但从来没有理解过。像某些消极的东西
scanfs不能正确读取值。
有些人可以给我一个关于这个问题的指针，特别是如何
安全使用scanf。
真诚地
b托马斯
B Thomas写道：
我正在阅读O''Reilly'的'Practical C programming"本书并警告不要使用scanf，建议避免完全使用它。
我同意这个建议，虽然肯定*可以*安全地使用scanf
。
相反，它建议使用使用fgets和sscanf。
我甚至不会使用sscanf，坦率地说。
但是没有提供
解释，除了那个scanf handels行尾非常糟糕。
相反，处理它们很棘手。
我在做一些数字编程时遇到过这样的问题，但从来没有理解过。像某些确定的扫描文件不能正确读取值。
有些人可以给我一个关于这个问题的指针，特别是如何安全地使用scanf。
我想，Dan Pop是你的男人。 IIRC他是这个
新闻组的唯一定期撰稿人，他认为使用scanf是个好主意。
-
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
Richard Heathfield写道：
B Thomas写道：
我正在阅读O''Reilly'的Practical C programming。本书并警告不要使用scanf，建议避免使用它。
我同意这个建议，尽管*使用scanf肯定是*可能*安全。
相反，它建议使用fgets和sscanf。
我甚至不会使用sscanf，坦率地说。
然而，除了那个扫描线以外，没有提供
解释非常糟糕。
更确切地说，处理它们很棘手。
我在做一些数字编程时遇到过这样的问题但却从未理解过。像某些连续的
scanfs这样的东西不能正确读取值。
有些人可以给我一个关于这个问题的指针，特别是如何安全地使用scanf。
我认为Dan Pop是你的男人。
IIRC他是这个
新闻组的唯一定期撰稿人，他认为使用scanf是一个好主意。
我已经在某人的家庭作业上实施了Dan'的技巧，
一次或两次。
http://groups.google.com/groups？ selm ... mindspring.com
我喜欢它。
他也有使用feof的变体。
http：/ /groups.google.com/groups?selm...unnews.cern.ch
-
pete
" B Thomas" <第***** @ math.ohio-state.edu>在消息中写道
有些人可以给我一个关于这个问题的指针，特别是如何安全地使用scanf。
scanf（"％s"，str）是伪装的gets（）。
但是scanf（）确实有自己的微型格式化语言
允许你分析字符串的最大宽度，如何处理
溢出等等。
我不知道这种格式化语言（尽管我很少从文字
文件）。你工作的很多程序员很可能也不会熟悉它。
Hi,
I was reading O''Reilly''s "Practical C programming" book and it warns
against the use of scanf, suggesting to avoid using it completely .
Instead it recomends to use using fgets and sscanf. However no
explanation is offered other than that scanf handels end of lines very
badly. I have exeperienced such problems when doing some numerical
programming but never understood it. Things like some consequitive
scanfs would not read in values correctly.
Could some please give me a pointer on this issue, in particular how to
use scanf safely.
sincerely
b thomas
B Thomas wrote:
Hi,
I was reading O''Reilly''s "Practical C programming" book and it warns
against the use of scanf, suggesting to avoid using it completely .
I agree with that advice, although it is certainly *possible* to use scanf
safely.
Instead it recomends to use using fgets and sscanf.
I wouldn''t even use sscanf, to be frank.
However no
explanation is offered other than that scanf handels end of lines very
badly.
Rather, handling them well is tricky.
I have exeperienced such problems when doing some numerical
programming but never understood it. Things like some consequitive
scanfs would not read in values correctly.
Could some please give me a pointer on this issue, in particular how to
use scanf safely.
Dan Pop is your man, I think. IIRC he''s the only regular contributor to this
newsgroup who thinks using scanf is a good idea.
--
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
Richard Heathfield wrote:
B Thomas wrote:Hi,
I was reading O''Reilly''s "Practical C programming" book and it warns
against the use of scanf, suggesting to avoid using it completely .
I agree with that advice, although it is certainly *possible* to use scanf
safely.Instead it recomends to use using fgets and sscanf.
I wouldn''t even use sscanf, to be frank.However no
explanation is offered other than that scanf handels end of lines very
badly.
Rather, handling them well is tricky.I have exeperienced such problems when doing some numerical
programming but never understood it. Things like some consequitive
scanfs would not read in values correctly.
Could some please give me a pointer on this issue,
in particular how to use scanf safely.
Dan Pop is your man, I think.
IIRC he''s the only regular contributor to this
newsgroup who thinks using scanf is a good idea.
I''ve implemented Dan''s technique on somebody''s homework,
once or twice.
http://groups.google.com/groups?selm...mindspring.com
I like it.
He also has a variation using feof.
http://groups.google.com/groups?selm...unnews.cern.ch
--
pete
"B Thomas" <th*****@math.ohio-state.edu> wrote in message
Could some please give me a pointer on this issue, in particular how to
use scanf safely.
scanf("%s", str) is gets() in disguise.
However scanf() does have its own minature formatting language that will
allow you to sepcify the maximum width of the string, how to handle
overflow, etc.
I don''t know this formatting language (though I seldom read fields from text
files). It''s likely that many of the programmers you work with won''t be
familiar with it either.
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