将String ^转换为std :: string（基本字符串） - >错误。我怎样才能解决这个问题？

I try to convert a String^ to basic string...but I get the error after this code. What does it mean and how can I fix it? I need to input basic string into a class constructor. The string^ would not work.

我尝试将String ^转换为基本字符串...但是在此代码之后我收到错误。它是什么意思,我该如何解决?我需要将基本字符串输入到类构造函数中。字符串^不起作用。

System::String^ temp = textBox1->Text;
string dummy = System::Convert::ToString(temp);

error C2440: 'initializing' : cannot convert from 'System::String ^' to 'std::basic_string'
1>        with
1>        [
1>            _Elem=char,
1>            _Traits=std::char_traits,
1>            _Ax=std::allocator
1>        ]
1>        No constructor could take the source type, or constructor overload resolution was ambiguous

6 个解决方案

#1

You need to marshal your string. The managed string sits somewhere on the managed heap (garbage collector is free to move it around).

你需要整理你的字符串。托管字符串位于托管堆上的某个位置(垃圾收集器可以*移动它)。

One way of getting the string to the native side is as follows:

将字符串传递给本机端的一种方法如下:

using System::Runtime::InteropServices::Marshal;

char *pString = (char*)Marshal::StringToHGlobalAnsi(managedString);
std::string nativeString(pString); // make your std::string
Marshal::FreeHGlobal(pString);     // don't forget to clean up

If you are using Visual Studio 2008, you can take advantage of much nicer marshaling utilities. Check out this MSDN page.

如果您使用的是Visual Studio 2008,则可以利用更好的编组实用程序。查看此MSDN页面。

#include <msclr/marshal.h>
#include <msclr/marshal_cppstd.h>

using namespace msclr::interop;

std::string nativeString(marshal_as<std::string>(managedString));

#2

I spend 11h to find a solution:

我花了11个小时才找到解决方案:

 #include <stdlib.h
 #include <string.h>
 #include <msclr\marshal_cppstd.h>
 //ListaQuad<int> prueba;
 //..
 using namespace msclr::interop;
 //..
 System::String^ clrString = (TextoDeBoton);
 std::string stdString = marshal_as<std::string>(clrString);  //String^ to std
 //System::String^ myString = marshal_as<System::String^>(MyBasicStirng);   //std to String^ (no lo he probado, pero sería algo así.)
 prueba.CopyInfo(stdString); //MyMethod
 //..
 //where, String^ = TextoDeBoton;
 //and, stdString = normal string;

#3

You need to do two things to convert a System::String to a std::string:

您需要做两件事来将System :: String转换为std :: string:

Marshal the memory from the managed heap an unmanaged one.

从托管堆中分配内存和非托管堆。

Convert your character encoding from a wide characters to (what looks like from your question) ansi characters.

将您的角色编码从宽字符转换为(从您的问题看起来像)ansi字符。

One way, without having to worry about freeing any HGlobal memory is to define a method along the lines of:

一种方法,无需担心释放任何HGlobal内存,就是定义一种方法:

interior_ptr<unsigned char> GetAsciiString(System::String ^s)
{
    array<unsigned char> ^chars = System::Text::Encoding::ASCII->GetBytes(s);
    return &chars[0];
    // of course you'd want to do some error checking for string length, nulls, etc..
}

And you'd use it like:

你会像以下一样使用它:

// somewhere else...
{
    pin_ptr<unsigned char> pChars = GetAsciiString(textBox1->Text);
    std:string std_str(pChars); // I don't have my compiler in front of me, so you may need a (char*)pChars
}

This also lets you use the encoding of your choice (like utf-8 over ascii), but you may not really need this.

这也允许您使用您选择的编码(如ascii上的utf-8),但您可能不需要这样。

#4

May be, you will need inverse converting, from std::string to String^. I was searching this converting, but I didn't find. So, I wrote it. I hope, it will be useful for somebody:

可能是,你需要逆转换,从std :: string到String ^。我正在寻找这种转换,但我没有找到。所以,我写了它。我希望,这对某些人有用:

String^ stdStringToPlatformString(string stdString){
    const size_t newsizew = strlen(stdString.c_str()) + 1;
    size_t convertedChars = 0;
    wchar_t *ch1 = new wchar_t[newsizew];
    mbstowcs_s(&convertedChars, ch1, newsizew, stdString.c_str(), _TRUNCATE);
    String ^platformString;
    platformString = ref new Platform::String(ch1, newsizew);
    return platformString;
}

#5

I think you can also just do:

我想你也可以这样做:

string dummy = string( textBox1->Text );

Check out How to: Convert Between Various String Types on MSDN.

请查看如何:在MSDN上转换各种字符串类型。

#6

string platformStringToStdString(String ^input){
    int size=input->Length()+1;
    char* auxiliary=(char *)malloc(sizeof(char)*size);
    wcstombs_s(NULL,auxiliary,size,input->Data(),_TRUNCATE);
    string result(auxiliary);
    free(auxiliary);
    return result;
}

#1