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我在让这个 COMPARE 宏工作时遇到问题。关于如何解决的任何想法？

它有点像人造样本——我想让它尽可能小。

#include <iostream>
#include <string.h>

enum rqtypes {Unknown, Monitor, Query, Snapshot };

class base {
public:
   base() : type(Unknown) {}
   rqtypes type;
};

class CBMonitorDeviceRequest : public base
{
public:
   CBMonitorDeviceRequest() : dn(0) {}
   char* dn;
};


//I want the equivalent of:
//        case MonitorDeviceRequestID:
//           CBMonitorDeviceRequest* pthis = static_cast<CBMonitorDeviceRequest*>(thisrq);
//           if(pthis && strcmp(pthis->dn1, "1234") == 0)
//              return 0;
//           else
//              return -1;
//           break;


int main(int argc, char* argv[])
{
   CBMonitorDeviceRequest* ptr = new CBMonitorDeviceRequest;
   ptr->type = Monitor;
   ptr->dn = new char(strlen("1234") + 1);
   strcpy(ptr->dn, "1234");

#define COMPARE(id, thismsg) case id##ID: { \
   CB##id * pthis = static_cast<CB##id *>(thismsg); \
   if(pthis && strcmp(pthis->dn, "1234") == 0) \
      std::cout << "found"; \
   else \
      std::cout << "not found"; \
     break;  } \

   switch(ptr->type){
      COMPARE(Monitor, ptr);
   }

#undef COMPARE

    return 0;
}

我得到例如：

(46) : error C2065: 'MonitorID' : undeclared identifier
(46) : error C2051: case expression not constant
(46) : error C2065: 'CBMonitor' : undeclared identifier
(46) : error C2065: 'pthis' : undeclared identifier
(46) : error C2061: syntax error : identifier 'CBMonitor'
(46) : error C2065: 'pthis' : undeclared identifier
(46) : error C2065: 'pthis' : undeclared identifier
(46) : error C2227: left of '->dn' must point to class/struct/union/generic type

使用 gcc -EI get: # 30 "macro_fun2.cpp" int main(int argc, char* argv[]) { CBMonitorDeviceRequest* ptr = new CBMonitorDeviceRequest; ptr->type = 监视器；ptr->dn = new char(strlen("1234") + 1); strcpy（ptr->dn，“1234”）；# 45 "macro_fun2.cpp" switch(ptr->type){ case MonitorID: { CBMonitor * pthis = static_cast(ptr); if(pthis && strcmp(pthis->dn, "1234") == 0) Monitor = Query; 否则监视器=快照；休息; }; }

返回0；}

*** By the way I changed code to to avoid the massive printing of iostream by preprocessor - otherwise -E printing would have been huge.

#define COMPARE(id, thismsg) case id##ID: { \
   CB##id * pthis = static_cast<CB##id *>(thismsg); \
   if(pthis && strcmp(pthis->dn, "1234") == 0) \
      id = Query; \
   else \
      id =  Snapshot; \
     break;  } \
4

2 回答 2

1

我想你想要CB##id，不是CBid##。

于 2012-09-28T15:27:04.367 回答
0

id##ID将扩展为MonitorID未定义的 。您要么想在 的定义中重命名Monitor为，要么将其更改为。MonitorIDrqtypesid

CB##id将扩展为CBMonitor，也未定义。您要么想重命名class CBMonitorDeviceRequest为class CBMonitor，要么将其更改为CB##id##DeviceRequest。

除此之外，我看不到任何明显的问题。当然，除了内存泄漏。你为什么不使用std::string你的字符串？

于 2012-09-28T15:34:07.917 回答