调用IOS :: exception（...）导致EOF从std :: getline（...）中抛出InteropServices.SEHException在C ++ - CLI，为什么？ [英] Calling IOS::exception(...) causes EOF to throw InteropServices.SEHException from std::getline(...) in C++-CLI, why?

问题描述

我运行以下函数加载文件。它正在从CLI移植到标准C ++，并且当我尝试指定我想抛出除EOF以外的所有异常时，会显示意外的行为。

  bool parseFile（ManagedClass *％parsedFileAsManagedObject，const string& fileName）; 
 std :: string line; 
 bool success = true; 
 ifstream is（fileName.c_str（））; 
 //除非我注释掉下面这行我得到的问题
 is.exceptions（ifstream :: badbit | ifstream :: failbit）; 
 // do stuff 
 try {
 while（getline（is，line））{
 // do stuff again 
 parsedFileAsManagedObject = gcnew ManagedClass（12，44） ; 
} 
} catch（Exception ^ ex）{
 log（ex-> ToString（）+ ex-> StackTrace + ex-> InnerException）; 
 success = false; 
 //点击调试器。 
} 
 return success; 
} 
  

当运行如上时，我得到：

$ _CxxThrowException（Void *，_s__ThrowInfo *）。

外部组件已抛出异常

<

在 std.ios_base.clear（ios_base *，Int32 _State，Boolean _Reraise）在 std中的c：\program files\microsoft visual studio 9.0 \vc\include\xiosbase：第294行





basic_ios< char，std :: char_traits< char> > .clear（basic_ios< char\，std :: char_traits< char>> *，Int32 _State，Boolean _Reraise） in c：\program files\ microsoft visual studio 9.0 \\ vc\include\ios：line 44

在 std.basic_ios< char，std :: char_traits< char> > .setstate（basic_ios< char\，std :: char_traits< char>> *，Int32 _State，Boolean _Reraise） in c：\program files\microsoft visual studio 9.0 \\ vc \include\ios：line 55

在 std.basic_istream< char，std :: char_traits< char> > ._ Ipfx（basic_istream< char\，std :: char_traits< char>> *，Boolean _Noskip） in c：\program files\microsoft visual studio 9.0 \vc \\ include \istream：line 120

在 std.basic_istream< char，std :: char_traits< char> > .sentry。{ctor}（sentry *，basic_istream< char\，std :: char_traits< char>> * _Istr，Boolean _Noskip） in c：\program files\microsoft visual studio 9.0 \vc\include\istream：line 76

在 std.getline< char，struct std :: char_traits< char> ;，class std :: allocator< char> >（basic_istream< char\，std :: char_traits< char>> * _Istr，basic_string< char\，std :: char_traits< char> \，std :: allocator< char> * _Str，SByte _Delim） in c：\ program files\microsoft visual studio 9.0 \vc\include\string：line 483

std.getline< char，struct std :: char_traits< char>，class std :: allocator< char> >（basic_istream< char\，std :: char_traits< char>> * _Istr，basic_string< char\，std :: char_traits< char> \，std :: allocator< char> / code>在c：\program files\microsoft visual studio 9.0 \vc\include\string：line 531

在 myprojrepeated.LevelParser.parseFile（ManagedClass *％parsedFileAsManagedObject，basic_string< char\，std :: char_traits< char> \，std :: allocator< char>> * fileName） c：\documents和settings\KingKewlio\my documents \visual studio 2008 \projects\myproj\myprojrepeated\levelparser.cpp：第355行

描述我的例外。

当我注释掉这一行，所有都在Interop的土地上。

任何人都可以解释为什么Interop不喜欢它？

我认为Interop是因为当我不打扰环绕 getline（...）在中尝试和 catch 错误

System.Runtime.InteropServices.SEHException

从上面和下面显示的调用堆栈顶部报告：

[管理到本机转换]

myproj.exe！std :: ios_base :: clear（int _State = 3，bool _Reraise = false） 294行+ 0x3a字节C ++

myproj.exe！std :: basic_ios< char，std :: char_traits< char> > :: clear（int _State = 3，bool _Reraise = false） 45行C ++

myproj.exe ！std :: basic_ios< char，std :: char_traits< char> > :: setstate（int _State = 2，bool _Reraise = false） 56行C ++

myproj.exe ！std :: basic_istream< char，std :: char_traits< char> > :: _ Ipfx（bool _Noskip = true）第121行C ++

myproj.exe！std :: basic_istream< ; char，std :: char_traits< char> > :: sentry :: sentry（std :: basic_istream< char，std :: char_traits< char>>& _Istr = {...}，bool _Noskip = true） 0x18字节C ++

myproj.exe！std :: getline< char，std :: char_traits< char>，std :: allocator< char> >（std :: basic_istream< char，std :: char_traits< char>>& _Istr = {...}，std :: basic_string< char，std :: char_traits< char>，std :: allocator< char> ;& _Str = {...}，char _Delim = 10''）第483 + 0xe字节C ++

myproj.exe！std :: getline< char，std :: char_traits< char>，std :: allocator< char> >（std :: basic_istream< char，std :: char_traits< char>>& _Istr = {...}，std :: basic_string< char，std :: char_traits< char>，std :: allocator< char> ;>& _Str = {...}）行531 + 0x33字节C ++

回答 http://stackoverflow.com/q/8144268/866333 到我上一个问题表示这是意外的行为，但我

code> std :: ios_base c $ c>抛出异常。因为它是C ++标准库的一部分，所以异常可能是 std :: exception& 。不是异常^ 。因为你的代码不捕获 std :: exception& ，它可能要终止。这可以通过添加

  catch（...）{
 log（Unknown exception thrown！ ）; 
 throw; // rethrow it。总是返回未知的例外。期。 
} 
  

此外， getline code>将同时设置 EOF 和 failbit 该文件在空行结束。

I run the following function to load a file. It is being ported from CLI to standard C++ and exhibits unexpected behaviour when I attempt to specify that I would like to throw all exceptions except EOF.

bool parseFile(ManagedClass *%parsedFileAsManagedObject, const string &fileName);
    std::string line;
    bool success = true;
    ifstream is(fileName.c_str());
    //Unless I comment out the following line I get problems
    is.exceptions( ifstream::badbit | ifstream::failbit );
    //do stuff
    try {
        while (getline(is, line)) {
        //do stuff again
            parsedFileAsManagedObject = gcnew ManagedClass(12, 44);
        }
    } catch (Exception ^ex) {
        log(ex->ToString() + ex->StackTrace + ex->InnerException);
        success = false;
        //Hit debugger here.
    }
    return success;
}

When run as above I get:

External component has thrown an exception.

at _CxxThrowException(Void* , _s__ThrowInfo* )

at std.ios_base.clear(ios_base* , Int32 _State, Boolean _Reraise) in c:\program files\microsoft visual studio 9.0\vc\include\xiosbase:line 294

at std.basic_ios<char,std::char_traits<char> >.clear(basic_ios<char\,std::char_traits<char> >* , Int32 _State, Boolean _Reraise) in c:\program files\microsoft visual studio 9.0\vc\include\ios:line 44

at std.basic_ios<char,std::char_traits<char> >.setstate(basic_ios<char\,std::char_traits<char> >* , Int32 _State, Boolean _Reraise) in c:\program files\microsoft visual studio 9.0\vc\include\ios:line 55

at std.basic_istream<char,std::char_traits<char> >._Ipfx(basic_istream<char\,std::char_traits<char> >* , Boolean _Noskip) in c:\program files\microsoft visual studio 9.0\vc\include\istream:line 120

at std.basic_istream<char,std::char_traits<char> >.sentry.{ctor}(sentry* , basic_istream<char\,std::char_traits<char> >* _Istr, Boolean _Noskip) in c:\program files\microsoft visual studio 9.0\vc\include\istream:line 76

at std.getline<char,struct std::char_traits<char>,class std::allocator<char> >(basic_istream<char\,std::char_traits<char> >* _Istr, basic_string<char\,std::char_traits<char>\,std::allocator<char> >* _Str, SByte _Delim) in c:\program files\microsoft visual studio 9.0\vc\include\string:line 483

at std.getline<char,struct std::char_traits<char>,class std::allocator<char> >(basic_istream<char\,std::char_traits<char> >* _Istr, basic_string<char\,std::char_traits<char>\,std::allocator<char> >* _Str) in c:\program files\microsoft visual studio 9.0\vc\include\string:line 531

at myprojrepeated.LevelParser.parseFile(ManagedClass *%parsedFileAsManagedObject, basic_string<char\,std::char_traits<char>\,std::allocator<char> >* fileName) in c:\documents and settings\KingKewlio\my documents\visual studio 2008\projects\myproj\myprojrepeated\levelparser.cpp:line 355

describing my exception.

When I comment out that line all is well in the land of Interop.

Can anybody explain why Interop doesn't like it?

I attribute Interop because when I don't bother to surround that getline(...) in try and catch I get the following error

System.Runtime.InteropServices.SEHException

reported from the top of the call stack shown above and again below:

[Managed to Native Transition]

myproj.exe!std::ios_base::clear(int _State = 3, bool _Reraise = false) Line 294 + 0x3a bytes C++

myproj.exe!std::basic_ios<char,std::char_traits<char> >::clear(int _State = 3, bool _Reraise = false) Line 45 C++

myproj.exe!std::basic_ios<char,std::char_traits<char> >::setstate(int _State = 2, bool _Reraise = false) Line 56 C++

myproj.exe!std::basic_istream<char,std::char_traits<char> >::_Ipfx(bool _Noskip = true) Line 121 C++

myproj.exe!std::basic_istream<char,std::char_traits<char> >::sentry::sentry(std::basic_istream<char,std::char_traits<char> >& _Istr = {...}, bool _Noskip = true) Line 76 + 0x18 bytes C++

myproj.exe!std::getline<char,std::char_traits<char>,std::allocator<char> >(std::basic_istream<char,std::char_traits<char> >& _Istr = {...}, std::basic_string<char,std::char_traits<char>,std::allocator<char> >& _Str = {...}, char _Delim = 10 ' ') Line 483 + 0xe bytes C++

myproj.exe!std::getline<char,std::char_traits<char>,std::allocator<char> >(std::basic_istream<char,std::char_traits<char> >& _Istr = {...}, std::basic_string<char,std::char_traits<char>,std::allocator<char> >& _Str = {...}) Line 531 + 0x33 bytes C++

An answer http://stackoverflow.com/q/8144268/866333 to my previous question indicates that this is unexpected behaviour but I am prepared to be proved wrong.

解决方案

It would appear as if std::ios_base is throwing an exception. Since it is part of the C++ standard library, the exception is probably a std::exception &. Not a Exception ^. Since your code doesn't catch std::exception &, it is probably about to terminate. This can be confirmed by adding a

catch (...) {
    log("Unknown exception thrown!");
    throw;  //rethrow it.  ALWAYS RETHROW UNKNOWN EXCEPTIONS.  PERIOD.
}

Also, getline(is, line) will set both EOF and failbit both, if the file ends in an empty line.

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