小编Ben*_*ane的帖子

以下C++代码生成此错误:

error C2061: syntax error : identifier 'IObject'

这是我的代码:

file:IObject.h

#include "IIStreamable.h"
using namespace Serialization;
namespace Object
{
    class IObject : public IIStreamable
    {
        virtual void AcceptReader( IIReader* reader ); 
        virtual void AcceptWriter( IIWriter* writer );
    };
}

文件:IIWriter

#include "IObject.h"
#using namespace Object;
namespace Serialization
{
    class ICORE_API IIWriter
 {
public:
    // primitive "built in" value types
    virtual void writeChar(const char) =0;
    virtual void writeUChar(unsigned char) =0;
    virtual void writeCharPtr(const char*) =0;
    virtual void writeUCharPtr(const unsigned char*) =0;
    virtual …

我有

error C2894: templates cannot be declared to have 'C' linkage

当我尝试编译我的C ++项目时。

所有错误将我指向vc ++文件

1>c:\program files\microsoft visual studio 10.0\vc\include\iosfwd(32): error C2894: templates cannot be declared to have 'C' linkage
1>c:\program files\microsoft visual studio 10.0\vc\include\iosfwd(120): error C2894: templates cannot be declared to have 'C' linkage
1>c:\program files\microsoft visual studio 10.0\vc\include\iosfwd(133): error C2894: templates cannot be declared to have 'C' linkage
1>c:\program files\microsoft visual studio 10.0\vc\include\iosfwd(256): error C2894: templates cannot be declared to have 'C' linkage
1>c:\program files\microsoft visual studio 10.0\vc\include\iosfwd(279): …

我想知道如何确定我的元组是否为空？请注意,我将std :: tuble与std :: map结合使用,如下所示:

typedef std::tuple<SDESType,INT32,std::string> SDesItem;
typedef std::map<SDESType,SDesItem> SDesItemMap;

现在我想检查第二个值SDesItemMap,即元组是否为空？

if(SDesItems[SDESType] != NULL) // this is error