使用istream_iterator范围构造时无法访问向量

Question

我试图编译这段代码片段但是我遇到了编译错误:(!用Visual Studio 2010编译

#include <vector>
#include <string>
#include <sstream>
#include <iterator>
#include <iostream>

using namespace std;

int main() {
    string s( "Well well on" );
    istringstream in( s );
    vector<string> v( istream_iterator<string>( in ), istream_iterator<string>() );
    copy( v.begin(), v.end(), ostream_iterator<string>( cout, "\n" ) );
}

错误:

Error   1   error C2228: left of '.begin' must have class/struct/union  c:\visual studio 2008 projects\vector test\vector test\main.cpp 13  vector test
Error   2   error C2228: left of '.end' must have class/struct/union    c:\visual studio 2008 projects\vector test\vector test\main.cpp 13  vector test

发生了什么？矢量构造正确,我怎么能不能调用它？

最好的祝福,

Answer 1

我认为这

vector<string> v( istream_iterator<string>( in ), istream_iterator<string>() );

被解析为函数声明:

vector<string> v( istream_iterator<string> in, istream_iterator<string> );

这通常被称为"C++'最令人烦恼的解析".

我想一些额外的括号可以解决这个问题:

vector<string> v( (istream_iterator<string>(in)), (istream_iterator<string>()) );