C++ 将istream运算符与类交朋友

您好，我正试图将操作符

>

重载到我的类，但我在eclipse中发现了一个错误

代码：

代码2：

    friend istream& operator>>(const istream& is, const RAngle& ra)
{
    is >> ra.x;
    is >> ra.y;
    return is 
}

撞车了，我也不知道为什么，请帮忙

编辑：

ra.x

和

ra.y

都是我班的两个私人INT

完全错误：

错误：

   ..\/rightangle.h: In function 'std::istream& operator>>(std::istream&, const RAngle&)':
..\/rightangle.h:65:12: error: ambiguous overload for 'operator>>' in 'is >> ra.RAngle::x'
..\/rightangle.h:65:12: note: candidates are:
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:122:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__istream_type& (*)(std::basic_istream<_CharT, _Traits>::__istream_type&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] <near match>
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:122:7: note:   no known conversion for argument 1 from 'const int' to 'std::basic_istream<char>::__istream_type& (*)(std::basic_istream<char>::__istream_type&) {aka std::basic_istream<char>& (*)(std::basic_istream<char>&)}'
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:126:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__ios_type& (*)(std::basic_istream<_CharT, _Traits>::__ios_type&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>, std::basic_istream<_CharT, _Traits>::__ios_type = std::basic_ios<char>] <near match>
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:126:7: note:   no known conversion for argument 1 from 'const int' to 'std::basic_istream<char>::__ios_type& (*)(std::basic_istream<char>::__ios_type&) {aka std::basic_ios<char>& (*)(std::basic_ios<char>&)}'
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:133:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::ios_base& (*)(std::ios_base&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] <near match>
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:133:7: note:   no known conversion for argument 1 from 'const int' to 'std::ios_base& (*)(std::ios_base&)'
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:241:7: note: std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__streambuf_type*) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__streambuf_type = std::basic_streambuf<char>] <near match>
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:241:7: note:   no known conversion for argument 1 from 'const int' to 'std::basic_istream<char>::__streambuf_type* {aka std::basic_streambuf<char>*}'
..\/rightangle.h:66:12: error: ambiguous overload for 'operator>>' in 'is >> ra.RAngle::y'
..\/rightangle.h:66:12: note: candidates are:
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:122:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__istream_type& (*)(std::basic_istream<_CharT, _Traits>::__istream_type&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] <near match>
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:122:7: note:   no known conversion for argument 1 from 'const int' to 'std::basic_istream<char>::__istream_type& (*)(std::basic_istream<char>::__istream_type&) {aka std::basic_istream<char>& (*)(std::basic_istream<char>&)}'
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:126:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__ios_type& (*)(std::basic_istream<_CharT, _Traits>::__ios_type&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>, std::basic_istream<_CharT, _Traits>::__ios_type = std::basic_ios<char>] <near match>
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:126:7: note:   no known conversion for argument 1 from 'const int' to 'std::basic_istream<char>::__ios_type& (*)(std::basic_istream<char>::__ios_type&) {aka std::basic_ios<char>& (*)(std::basic_ios<char>&)}'
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:133:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::ios_base& (*)(std::ios_base&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] <near match>
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:133:7: note:   no known conversion for argument 1 from 'const int' to 'std::ios_base& (*)(std::ios_base&)'
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:241:7: note: std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__streambuf_type*) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__streambuf_type = std::basic_streambuf<char>] <near match>
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:241:7: note:   no known conversion for argument 1 from 'const int' to 'std::basic_istream<char>::__streambuf_type* {aka std::basic_streambuf<char>*}''

。\/rightangle.h:在函数“std:：istream&operator>>（std:：istream&，const RAngle&）”中：
..\/rightangle.h:65:12:错误：“is>>ra.RAngle:：x”中“operator>>”的重载不明确
..\/rightangle.h:65:12:注：候选人为：
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:122:7：注：std:：basic\u istream:：：\u istream类型和std:：basic\u istream:：operator>（std:：basic\u istream:：\u istream类型和（*）（std:：basic\u istream:：：：\u istream类型和）[带字符，\u traituds=char:：char\u traituds，std:：basic\u istream:\u类型]
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:122:7：注意：参数1从“const int”到“std:：basic\u istream:：：_istream类型和（*）（std:：basic\u istream:：_istream类型和）{aka std:：basic\u istream&（*）（std:：basic\u istream&）}
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:126:7：注：std:：basic\u istream:：：：\u istream类型&std:：basic\u istream:：operator>（std:：basic\u istream:：\u ios类型（*）（std:：basic\u istream:&:：\u ios类型&）[with(u CharT=char，_Traits=std:：char\u Traits，std:：basic\u istream:：：(uu istream\u type=std:：basic\u istream，std:：basic\u istream:：(uu ios\u type=std:：basic\u ios]
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:126:7：注意：参数1从“const int”到“std:：basic\u istream:：：_ios_type&（*）（std:：basic\u istream:：_ios_type&）{aka std:：basic_ios&（*）（std:：basic_ios&）}
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:133:7：注：std:：basic\u istream:：：：\u istream类型和std:：basic\u istream:：operator>（std:：ios\u base&（*）（std:：ios\u base&）[带字符，\u traitracts=std:：char\u traitracts，std:：basic\u istream:：\u type=std:：basic\u istream:：]
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:133:7:注意：参数1从'const int'到'std:：ios_base&（*）（std:：ios_base&）'的转换未知
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:241:7：注：std:：basic_-istream&std:：basic_-istream:：operator>>（std:：basic_-istream:：：_-streambuf-type*）[with _-CharT=char，_-traituds=char:：Traits，std:：basic_-istream:：_-streambuf-type=std:：basic(基本(-streambuf-buf-type=std]
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:241:7：注意：参数1从“const int”到“std:：basic\u istream:：：_streambuf_type*{aka std:：basic\u streambuf*}没有已知的转换
..\/rightangle.h:66:12:错误：“is>>ra.RAngle:：y”中“operator>>”的重载不明确
..\/rightangle.h:66:12:注：候选人为：
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:122:7：注：std:：basic\u istream:：：\u istream类型和std:：basic\u istream:：operator>（std:：basic\u istream:：\u istream类型和（*）（std:：basic\u istream:：：：\u istream类型和）[带字符，\u traituds=char:：char\u traituds，std:：basic\u istream:\u类型]
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:122:7：注意：参数1从“const int”到“std:：basic\u istream:：：_istream类型和（*）（std:：basic\u istream:：_istream类型和）{aka std:：basic\u istream&（*）（std:：basic\u istream&）}
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:126:7：注：std:：basic\u istream:：：：\u istream类型&std:：basic\u istream:：operator>（std:：basic\u istream:：\u ios类型（*）（std:：basic\u istream:&:：\u ios类型&）[with(u CharT=char，_Traits=std:：char\u Traits，std:：basic\u istream:：：(uu istream\u type=std:：basic\u istream，std:：basic\u istream:：(uu ios\u type=std:：basic\u ios]
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:126:7：注意：参数1从“const int”到“std:：basic\u istream:：：_ios_type&（*）（std:：basic\u istream:：_ios_type&）{aka std:：basic_ios&（*）（std:：basic_ios&）}
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:133:7：注：std:：basic\u istream:：：：\u istream类型和std:：basic\u istream:：operator>（std:：ios\u base&（*）（std:：ios\u base&）[带字符，\u traitracts=std:：char\u traitracts，std:：basic\u istream:：\u type=std:：basic\u istream:：]
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:133:7:注意：参数1从'const int'到'std:：ios_base&（*）（std:：ios_base&）'的转换未知
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:241:7：注：std:：basic_-istream&std:：basic_-istream:：operator>>（std:：basic_-istream:：：_-streambuf-type*）[with _-CharT=char，_-traituds=char:：Traits，std:：basic_-istream:：_-streambuf-type=std:：basic(基本(-streambuf-buf-type=std]
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/istream:241:7:注意：参数1从“const int”到“std:：basic\u istream:：：”streambuf_type*{aka std:：basic\u streambuf*}”的转换未知

请从参数“const RAngle&ra”中删除const。您不能从方法中修改常量引用。

请从参数“const RAngle&ra”中删除const。您不能从方法中修改常量引用。

运算符的签名中存在一个问题：

friend istream& operator>>(const istream& is, const RAngle& ra){
//                         ^^^^^              ^^^^^
    return is >> ra.x >> ra.y;
}

---

如果参数是

const

，您将无法修改它们。截至错误消息，它们似乎表明编译器未能为

is>>ra.x

和

is>>ra.y

找到适当的重载。这可能与上一个问题有关（找不到采用const左值的重载）或否，取决于

ra.x

和

ra.y

的类型（问题中未显示）。

一个问题是操作员的签名：

friend istream& operator>>(const istream& is, const RAngle& ra){
//                         ^^^^^              ^^^^^
    return is >> ra.x >> ra.y;
}

如果参数是

const

，您将无法修改它们。截至错误消息，它们似乎表明编译器未能找到

is>>ra.x

和

is>>ra.y

的适当重载。

friend std::istream &operator>>(std::istream &is, RAngle &ra) { 
    return is >> ra.x >> ra.y;
}