为什么我的 istream_iterator 不起作用？
Why does my istream_iterator not work?
这是我写的代码。我正在使用 Visual studio 并学习如何使用标准模板库。当我尝试从源打印时，ostream_iterator 也不起作用。它给出了一个巨大的错误列表，那些我不可能理解的。
这是 完整的 代码，我正试图 运行 在 Visual Studio 中。会不会是软件设置有问题？
#include <iostream>
#include <vector>
#include <list>
#include <iterator>
#include <functional>
using namespace std;
//stream_iterator
int main() {
vector<string> source = { "31", "3113" };
copy(istream_iterator<string>(cin), istream_iterator<string>(),back_inserter(source)); //can't understand why this won't work
return 0;
}
These below are the error messages.
1>------ Build started: Project: StreamIters, Configuration: Debug Win32 ------
1> Source.cpp
1>c:\program files (x86)\microsoft visual studio 12.0\vc\include\iterator(256): error C2679: binary '>>' : no operator found which takes a right-hand operand of type 'std::string' (or there is no acceptable conversion)
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(485): could be 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(std::basic_streambuf<char,std::char_traits<char>> *)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(466): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(void *&)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(448): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(long double &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(430): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(double &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(411): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(float &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(392): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(unsigned __int64 &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(373): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(__int64 &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(353): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(unsigned long &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(335): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(long &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(317): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(unsigned int &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(291): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(int &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(272): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(unsigned short &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(237): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(short &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(218): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(std::_Bool &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(211): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(std::ios_base &(__cdecl *)(std::ios_base &))'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(204): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(std::basic_ios<char,std::char_traits<char>> &(__cdecl *)(std::basic_ios<char,std::char_traits<char>> &))'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(198): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(std::basic_istream<char,std::char_traits<char>> &(__cdecl *)(std::basic_istream<char,std::char_traits<char>> &))'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(1103): or 'std::basic_istream<char,std::char_traits<char>> &std::operator >><char,std::char_traits<char>,_Ty>(std::basic_istream<char,std::char_traits<char>> &&,_Ty &)'
1> with
1> [
1> _Ty=std::string
1> ]
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(1093): or 'std::basic_istream<char,std::char_traits<char>> &std::operator >><std::char_traits<char>>(std::basic_istream<char,std::char_traits<char>> &,unsigned char &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(1086): or 'std::basic_istream<char,std::char_traits<char>> &std::operator >><std::char_traits<char>>(std::basic_istream<char,std::char_traits<char>> &,unsigned char *)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(1079): or 'std::basic_istream<char,std::char_traits<char>> &std::operator >><std::char_traits<char>>(std::basic_istream<char,std::char_traits<char>> &,signed char &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(1072): or 'std::basic_istream<char,std::char_traits<char>> &std::operator >><std::char_traits<char>>(std::basic_istream<char,std::char_traits<char>> &,signed char *)'
1> while trying to match the argument list '(std::basic_istream<char,std::char_traits<char>>, std::string)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\iterator(255) : while compiling class template member function 'void std::istream_iterator<std::string,char,std::char_traits<char>,ptrdiff_t>::_Getval(void)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\iterator(222) : see reference to function template instantiation 'void std::istream_iterator<std::string,char,std::char_traits<char>,ptrdiff_t>::_Getval(void)' being compiled
1> c:\users\mahe\documents\visual studio 2013\projects\streamiters\streamiters\source.cpp(19) : see reference to class template instantiation 'std::istream_iterator<std::string,char,std::char_traits<char>,ptrdiff_t>' being compiled
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
代码中缺少 header <string>。虽然使用的接口确实要求至少有一个 std::string 的声明可用，但不要求您包含的 header 提供 std::string and/or 函数的定义在他们。我没有安装 MSVC++，但您包含的 header 似乎提供了 std::string 的定义，但没有输入或输出运算符的声明。
根据经验，您永远不应依赖间接包含。相反，您应该始终明确地包括所有相关的 headers：尽管声明目前可能可用，但 headers 可能会更改为不包括其他 headers。
这是我写的代码。我正在使用 Visual studio 并学习如何使用标准模板库。当我尝试从源打印时，ostream_iterator 也不起作用。它给出了一个巨大的错误列表，那些我不可能理解的。
这是 完整的 代码，我正试图 运行 在 Visual Studio 中。会不会是软件设置有问题？
#include <iostream>
#include <vector>
#include <list>
#include <iterator>
#include <functional>
using namespace std;
//stream_iterator
int main() {
vector<string> source = { "31", "3113" };
copy(istream_iterator<string>(cin), istream_iterator<string>(),back_inserter(source)); //can't understand why this won't work
return 0;
}
These below are the error messages.
1>------ Build started: Project: StreamIters, Configuration: Debug Win32 ------
1> Source.cpp
1>c:\program files (x86)\microsoft visual studio 12.0\vc\include\iterator(256): error C2679: binary '>>' : no operator found which takes a right-hand operand of type 'std::string' (or there is no acceptable conversion)
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(485): could be 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(std::basic_streambuf<char,std::char_traits<char>> *)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(466): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(void *&)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(448): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(long double &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(430): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(double &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(411): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(float &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(392): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(unsigned __int64 &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(373): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(__int64 &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(353): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(unsigned long &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(335): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(long &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(317): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(unsigned int &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(291): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(int &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(272): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(unsigned short &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(237): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(short &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(218): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(std::_Bool &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(211): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(std::ios_base &(__cdecl *)(std::ios_base &))'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(204): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(std::basic_ios<char,std::char_traits<char>> &(__cdecl *)(std::basic_ios<char,std::char_traits<char>> &))'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(198): or 'std::basic_istream<char,std::char_traits<char>> &std::basic_istream<char,std::char_traits<char>>::operator >>(std::basic_istream<char,std::char_traits<char>> &(__cdecl *)(std::basic_istream<char,std::char_traits<char>> &))'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(1103): or 'std::basic_istream<char,std::char_traits<char>> &std::operator >><char,std::char_traits<char>,_Ty>(std::basic_istream<char,std::char_traits<char>> &&,_Ty &)'
1> with
1> [
1> _Ty=std::string
1> ]
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(1093): or 'std::basic_istream<char,std::char_traits<char>> &std::operator >><std::char_traits<char>>(std::basic_istream<char,std::char_traits<char>> &,unsigned char &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(1086): or 'std::basic_istream<char,std::char_traits<char>> &std::operator >><std::char_traits<char>>(std::basic_istream<char,std::char_traits<char>> &,unsigned char *)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(1079): or 'std::basic_istream<char,std::char_traits<char>> &std::operator >><std::char_traits<char>>(std::basic_istream<char,std::char_traits<char>> &,signed char &)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\istream(1072): or 'std::basic_istream<char,std::char_traits<char>> &std::operator >><std::char_traits<char>>(std::basic_istream<char,std::char_traits<char>> &,signed char *)'
1> while trying to match the argument list '(std::basic_istream<char,std::char_traits<char>>, std::string)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\iterator(255) : while compiling class template member function 'void std::istream_iterator<std::string,char,std::char_traits<char>,ptrdiff_t>::_Getval(void)'
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\iterator(222) : see reference to function template instantiation 'void std::istream_iterator<std::string,char,std::char_traits<char>,ptrdiff_t>::_Getval(void)' being compiled
1> c:\users\mahe\documents\visual studio 2013\projects\streamiters\streamiters\source.cpp(19) : see reference to class template instantiation 'std::istream_iterator<std::string,char,std::char_traits<char>,ptrdiff_t>' being compiled
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
代码中缺少 header <string>。虽然使用的接口确实要求至少有一个 std::string 的声明可用，但不要求您包含的 header 提供 std::string and/or 函数的定义在他们。我没有安装 MSVC++，但您包含的 header 似乎提供了 std::string 的定义，但没有输入或输出运算符的声明。
根据经验，您永远不应依赖间接包含。相反，您应该始终明确地包括所有相关的 headers：尽管声明目前可能可用，但 headers 可能会更改为不包括其他 headers。