STL：你能否让这个片段更有效率 [英] STL: Could you make this snippet more efficient
问题描述
亲爱的comp.lang.c ++，
你能让这个片段效率更高吗？如你所见，我在代码中引入了太多
变量。
//在STL中逐行读取文件中的整数集设置
// fp是预先定义的
for（;！fp.eof（）;）
{
string linestr;
getline（fp，linestr）;
istringstream strstreamline（linestr）;
istream_iterator< unsigned intintstream（strstreamline）;
set< unsigned intpckset;
copy（intstream，istream_iterator< unsigned int>（），
inserter（modpckset，modpckset.begin（） ））;
}
提前致谢。
< a href =mailto：pe ****** @ gmail.com> pe ****** @ gmail.com 写道：
亲爱的comp.lang.c ++，
你能让这个片段效率更高吗？如你所见，我在代码中引入了太多
变量。
//在STL中逐行读取文件中的整数集设置
// fp是预先定义的
for（;！fp.eof（）;）
{
string linestr;
getline（fp，linestr）;
istringstream strstreamline（linestr）;
istream_iterator< unsigned intintstream（strstreamline）;
set< unsigned intpckset;
这是为了什么？
copy（intstream，istream_iterator< unsigned int>（） ，
inserter（modpckset，modpckset.begin（）））;
}
V
-
请在通过电子邮件回复时删除资金''A'
我没有回复最热门的回复，请不要不要问
12月3日上午11：37，Victor Bazarov < v.Abaza ... @ comAcast.netwrote：
pedag ... @ gmail.com写道：
亲爱的comp.lang.c ++，
你能否让这个片段更有效率？如你所见，我在代码中引入了太多
变量。
//在STL集中逐行读取文件中的整数集
// fp是预先定义
for（;！fp.eof（）;）
{
string linestr;
getline（fp，linestr）;
istringstream strstreamline（linestr）;
istream_iterator< unsigned intintstream（strstreamline）;
set< unsigned intpckset;
这是为了什么？
copy（intstream，istream_iterator< unsigned int>（） ，
inserter（modpckset，modpckset.begin（）））;
}
V
-
请在通过电子邮件回复时删除资金''A'
我没有回复最热门的回复，请不要'不要问
*更正*'''pckset''应该是''modpckset''。
< blockquote> pe******@gmail.com 写道：
12月3日上午11：37，Victor Bazarov < v.Abaza ... @ comAcast.netwrote：
> pedag ... @ gmail.com写道：
>>亲爱的comp.lang.c ++，
>>你能否让这个片段更有效率？如您所见，我在代码中引入了很多变量。
>> //在STL中逐行读取文件中的整数集// fp是预先定义
（;！fp.eof（）;）
{
字符串linestr;
getline（fp，linestr）;
istringstream strstreamline（linestr） ;
istream_iterator< unsigned intintstream（strstreamline）;
set< unsigned intpckset;
这是为了什么？
>> copy（intstream，istream_iterator< unsigned int>（） ，
inserter（modpckset，modpckset.begin（）））;
}
V
-
请删除资金'' A'在回复电子邮件时
我没有回复最热门的回复，请不要问
*更正*' 'pckset''应该是''modpckset''。
好的。通过删除
getline（fp，linestr）之间的界限，可以提高整个代码段的效率;
和
}
;他们基本上没有任何会产生副作用的工作。
创建一个字符串流，从中读取内容，以及将这些未签名的内容放入本地集合中的
是浪费
CPU周期。
V
-
请删除大写''A'通过电子邮件回复
我没有回复最热门的回复，请不要问
Dear comp.lang.c++,
Could you make this snippet more efficient? As you see I have too many
variables introduced in the code.
//Read set of integers from a file on line by line basis in a STL set
//fp is pre-defined
for(;!fp.eof();)
{
string linestr;
getline(fp,linestr);
istringstream strstreamline(linestr);
istream_iterator<unsigned intintstream(strstreamline);
set<unsigned intpckset;
copy ( intstream , istream_iterator<unsigned int>() ,
inserter(modpckset,modpckset.begin ( ) ));
}
Thanks in advance.
pe******@gmail.com wrote:Dear comp.lang.c++,
Could you make this snippet more efficient? As you see I have too many
variables introduced in the code.
//Read set of integers from a file on line by line basis in a STL set
//fp is pre-defined
for(;!fp.eof();)
{
string linestr;
getline(fp,linestr);
istringstream strstreamline(linestr);
istream_iterator<unsigned intintstream(strstreamline);
set<unsigned intpckset;What''s that for?
copy ( intstream , istream_iterator<unsigned int>() ,
inserter(modpckset,modpckset.begin ( ) ));
}V
--
Please remove capital ''A''s when replying by e-mail
I do not respond to top-posted replies, please don''t ask
On Dec 3, 11:37 am, "Victor Bazarov" <v.Abaza...@comAcast.netwrote:pedag...@gmail.com wrote:Dear comp.lang.c++,
Could you make this snippet more efficient? As you see I have too many
variables introduced in the code.
//Read set of integers from a file on line by line basis in a STL set
//fp is pre-defined
for(;!fp.eof();)
{
string linestr;
getline(fp,linestr);
istringstream strstreamline(linestr);
istream_iterator<unsigned intintstream(strstreamline);
set<unsigned intpckset;
What''s that for?
copy ( intstream , istream_iterator<unsigned int>() ,
inserter(modpckset,modpckset.begin ( ) ));
}
V
--
Please remove capital ''A''s when replying by e-mail
I do not respond to top-posted replies, please don''t ask*Correction* ''pckset'' should have been ''modpckset''.
pe******@gmail.com wrote:On Dec 3, 11:37 am, "Victor Bazarov" <v.Abaza...@comAcast.netwrote:>pedag...@gmail.com wrote:>>Dear comp.lang.c++,
>>Could you make this snippet more efficient? As you see I have too
many variables introduced in the code.
>>//Read set of integers from a file on line by line basis in a STL
set //fp is pre-defined
for(;!fp.eof();)
{
string linestr;
getline(fp,linestr);
istringstream strstreamline(linestr);
istream_iterator<unsigned intintstream(strstreamline);
set<unsigned intpckset;
What''s that for?
>>copy ( intstream , istream_iterator<unsigned int>() ,
inserter(modpckset,modpckset.begin ( ) ));
}
V
--
Please remove capital ''A''s when replying by e-mail
I do not respond to top-posted replies, please don''t ask
*Correction* ''pckset'' should have been ''modpckset''.OK. The entire snippet can be made more efficient by removing
the lines between
getline(fp, linestr);
and
}
; they do essentially no work that would have side effects.
The creation of a stringstream, reading stuff from it, and
putting those unsigned ints into a local set are a waste of
CPU cycles.
V
--
Please remove capital ''A''s when replying by e-mail
I do not respond to top-posted replies, please don''t ask
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