如何复制cin

Question

我试过了

auto cin2 = cin;
int a;
cin2 >> a;

但是编译器只给我无法理解的错误：

/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../include/c++/4.4.7/bits/ios_base.h: In copy constructor ‘std::basic_ios<char, std::char_traits<char> >::basic_ios(const std::basic_ios<char, std::char_traits<char> >&)’:
/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../include/c++/4.4.7/bits/ios_base.h:790: error: ‘std::ios_base::ios_base(const std::ios_base&)’ is private
/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../include/c++/4.4.7/iosfwd:47: error: within this context
/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../include/c++/4.4.7/iosfwd: In copy constructor ‘std::basic_istream<char, std::char_traits<char> >::basic_istream(const std::basic_istream<char, std::char_traits<char> >&)’:
/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../include/c++/4.4.7/iosfwd:53: note: synthesized method ‘std::basic_ios<char, std::char_traits<char> >::basic_ios(const std::basic_ios<char, std::char_traits<char> >&)’ first required here
test.cpp: In function ‘int main()’:
test.cpp:6: note: synthesized method ‘std::basic_istream<char, std::char_traits<char> >::basic_istream(const std::basic_istream<char, std::char_traits<char> >&)’ first required here

正确的做法是什么？

Answer 1

标准classstd::istream不可复制。您可以通过以下方式声明对 std::cin 的引用

decltype(auto) cin2 = ( std::cin );
int a;
cin2 >> a;

或者你可以这样写

auto &cin2 = std::cin;

要实现 istream 迭代器，您可以使用流的引用或指针。

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