STL速度 [英] STL speed
问题描述
任务确实很简单。阅读2.000.000字（平均长度= 9），排序
将它们写入新文件。
我已经用STL制作了它，它差不多了比我之前的版本慢了17倍
" clear-C-code"。
我使用了< vector>，< algorithm>，< iostream>和<算法>。 STL真的如此
慢吗？
thx in adv。
Przemo
ps我知道STL使用的是IntrospectiveSort，这似乎是不错的选择，我认为INPUT（cin）非常慢，
和< vector>作为一个动态结构也不是快速...任何想法？
Hi,
The task was indeed simple. Read 2.000.000 words (average length = 9), sort
them and write it to new file.
I''ve made this in STL, and it was almost 17 times slower than my previous
"clear-C-code".
I used <vector>, <algorithm>, <iostream> and <algorithm>. Is STL really so
slow?
Thx in adv.
Przemo
p.s. i know that STL uses IntrospectiveSort which seems to be good choice, i
suppose that INPUT (cin) is extremaly slow,
and <vector> as a dynamic structure also isn''t to fast... any ideas?
推荐答案
" Przemo Drochomirecki" < PE ****** @ gazeta.pl>在留言中写道
news：bt ********** @ nemesis.news.tpi.pl ...
"Przemo Drochomirecki" <pe******@gazeta.pl> wrote in message
news:bt**********@nemesis.news.tpi.pl...
任务确实很简单。读取2.000.000个单词（平均长度= 9），
对它们进行排序并将其写入新文件。
我已经在STL中创建了它，它比我之前的那个慢了近17倍/>clear-C-code。
我使用< vector>，< algorithm>，< iostream>和<算法>。 STL真的如此缓慢吗？
请问赞助。
Przemo
p.s.我知道STL使用IntrospectiveSort似乎是一个不错的选择，
我认为INPUT（cin）非常慢，
和< vector>作为一个动态的结构也不是要快......任何想法？
Hi,
The task was indeed simple. Read 2.000.000 words (average length = 9), sort them and write it to new file.
I''ve made this in STL, and it was almost 17 times slower than my previous
"clear-C-code".
I used <vector>, <algorithm>, <iostream> and <algorithm>. Is STL really so
slow?
Thx in adv.
Przemo
p.s. i know that STL uses IntrospectiveSort which seems to be good choice, i suppose that INPUT (cin) is extremaly slow,
and <vector> as a dynamic structure also isn''t to fast... any ideas?
我怀疑它本身就很慢。这取决于实施。我记得跟踪MS编译器上的流输出并发现
它编写了一个格式字符串并称为sprintf！银行里有五十亿美元，但是他们选择了最便宜，最糟糕的实施方案。
DW
I doubt that it''s inherently slow. It depends on the implementation. I
remember tracing through the stream output on an MS compiler and discovered
that it fabricated a format string and called sprintf! Fifty billion dollars
in the bank, but they chose the cheapest, nastiest implementation possible.
DW
" Przemo Drochomirecki" < PE ****** @ gazeta.pl>写在
新闻：bt ********** @ nemesis.news.tpi.pl：
"Przemo Drochomirecki" <pe******@gazeta.pl> wrote in
news:bt**********@nemesis.news.tpi.pl:
任务确实很简单。读取2.000.000个单词（平均长度= 9），对它们进行排序并将其写入新文件。
我在STL中做了这个，它比我的
previousclear-C-code。
我使用了< vector>，< algorithm>，< iostream>和<算法>。 STL
真的这么慢吗？
请问赞助。
Przemo
p.s.我知道STL使用IntrospectiveSort似乎是很好的选择，我认为INPUT（cin）非常慢，
和< vector>作为一个动态结构也不是禁止......任何想法？
Hi,
The task was indeed simple. Read 2.000.000 words (average length = 9),
sort them and write it to new file.
I''ve made this in STL, and it was almost 17 times slower than my
previous "clear-C-code".
I used <vector>, <algorithm>, <iostream> and <algorithm>. Is STL
really so slow?
Thx in adv.
Przemo
p.s. i know that STL uses IntrospectiveSort which seems to be good
choice, i suppose that INPUT (cin) is extremaly slow,
and <vector> as a dynamic structure also isn''t to fast... any ideas?
你没有发布你的clear-C-code，也没有你的标准C ++代码，因此
我们甚至无法猜测你做得不够好。
凝视我的水晶球说你没有用C和C ++表达相同的
程序。
You didn''t post your "clear-C-code", nor your Standard C++ code, thus there
is no way for us to even guess at what you''ve done inefficiently.
Gazing into my crystal ball says that you haven''t expressed the same
program in C and C++.
> STL真的这么慢吗？
没有源代码就很难说，这取决于很多其他的东西，比如STL实现编译器。
我会编写如下程序：
#include< algorithm>
#include < iterator>
#include< iostream>
#include< fstream>
#include< string>
#include< vector>
使用命名空间std;
int main（）
{
ifstream file（" input.txt"）;
vector< string>单词（istream_iterator< string>（file），
（istream_iterator< string>（）））;
sort（words.begin（），words.end（）） ;
ofstream outfile（" output.txt"）;
copy（words.begin（），words.end（），ostream_iterator< string>（outfile，" ; \ n"））;
}
问候
Ignaz
> Is STL really so slow?
That''s hard to say without the source and it depends on quite a few other
things, like the STL implementation and the Compiler.
I''d write the programm as following:
#include <algorithm>
#include <iterator>
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
using namespace std;
int main()
{
ifstream file("input.txt");
vector<string> words(istream_iterator<string>(file),
(istream_iterator<string>()));
sort(words.begin(), words.end());
ofstream outfile("output.txt");
copy(words.begin(), words.end(), ostream_iterator<string>(outfile, "\n"));
}
Regards
Ignaz
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