In <[EMAIL PROTECTED]>, Licheng Fang
wrote:
> Hi, I'm learning STL and I wrote some simple code to compare the
> efficiency of python and STL.
>
> //C++
> #include <iostream>
> #include <string>
> #include <vector>
> #include <set>
> #include <algorithm>
> using namespace std;
>
> int main(){
> vector<string> a;
> for (long int i=0; i<10000 ; ++i){
> a.push_back("What do you know?");
> a.push_back("so long...");
> a.push_back("chicken crosses road");
> a.push_back("fool");
> }
> set<string> b(a.begin(), a.end());
> unique_copy(b.begin(), b.end(), ostream_iterator<string>(cout, "\n"));
> }
Why are you using `unique_copy` here?
> #python
> def f():
> a = []
> for i in range(10000):
> a.append('What do you know')
> a.append('so long...')
> a.append('chicken crosses road')
> a.append('fool')
> b = set(a)
> for s in b:
> print s
>
> I was using VC++.net and IDLE, respectively. I had expected C++ to be
> way faster. However, while the python code gave the result almost
> instantly, the C++ code took several seconds to run! Can somebody
> explain this to me? Or is there something wrong with my code?
There's a difference in data structures at least. The Python `set` type
is implemented with a hash algorithm, so the equivalent STL type would be
`hash_set`. `set` in Python does not store its contents sorted.
Ciao,
Marc 'BlackJack' Rintsch
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