const_iterator not able to convert in char pointer

[mini20071985]

hi all,

I am trying to run a c++ code, which is a open source. And already tested visual studio 6 and .NET 2003. I am trying to run it on VS 2005. The code is this:-

bool OpenIPMPDOIContentInfoManager::ParseHostIPPort(const std::string& hostURL,
    std::string& hostIP, int& hostPort) {
  char* colon = strchr(hostURL.data(), ':');(1st error)
  if (colon == NULL) {
    return false;
  }
  hostIP = std::string(hostURL.begin(), std::string::const_iterator(colon));(2nd error)
  hostPort = atoi(++colon);
  return true;
}

And it's giving following error

error C2440: 'initializing' : cannot convert from 'const char *' to 'char *'
        Conversion loses qualifiers
error C2440: '<function-style-cast>' : cannot convert from 'char *' to 'std::_String_const_iterator<_Elem,_Traits,_Alloc>'
        with
        [
            _Elem=char,
            _Traits=std::char_traits<char>,
            _Alloc=std::allocator<char>
        ]
        No constructor could take the source type, or constructor overload resolution was ambiguous

here second error is coming because const_iterator is using as a constructor.

Can anybody suggest what's wrong with the code. Is it bcoz of compiler?
Thanks in advance

[Peter87]

hostURL.data() gives you a const char* so the const version of strchr will be called, returning a const char*. Change the type of colon to const char*.

std::string::const_iteratorcolon are you trying to cast a pointer into a std::string::const_iterator? Don't do that. You can use pointers as iterators so this should work:
hostIP = std::string(hostURL.data(), colon);

[mini20071985]

thanks Peter for the reply.
I did what you have said. First error has gone. After changing hostip, now its giving following error

'std::basic_string<_Elem,_Traits,_Ax>::basic_string' : none of the 13 overloads could convert all the argument types
        with
        [
            _Elem=char,
            _Traits=std::char_traits<char>,
            _Ax=std::allocator<char>
        ]

[viliml]

try hostURL.cbegin() instead on line 7, and hostPort=atoi(colon+1); on line 8.

[mini20071985]

Hi viliml, thanks for the reply.

I did what you have said. It's giving error for that too. Here is the code snippet:

bool OpenIPMPDOIContentInfoManager::ParseHostIPPort(const std::string& hostURL,
    std::string& hostIP, int& hostPort) {
  const char* colon = strchr(hostURL.data(), ':');
  if (colon == NULL) {
    return false;
  }
  
	//std::string::const_iterator p = *colon;
  hostIP = std::string(hostURL.cbegin(),colon);
  hostPort = atoi(colon+1);
  return true;
}

here is the error

error C2039: 'cbegin' : is not a member of 'std::basic_string<_Elem,_Traits,_Ax>'
        with
        [
            _Elem=char,
            _Traits=std::char_traits<char>,
            _Ax=std::allocator<char>
        ]

just wanted to mention that code was tested on visual 6 and .NET 2003. But i am running it on 2005 because of the unavailability of these two IDE.

I am not very much familiar with these type of c++ programming, but i feel that in 2005 const_iterators implementation has been changed. So it's not able to work on char pointer.

Thanks

[mini20071985]

Hi Peter and viliml,

I made following change in the code and now it's compiling, but i don't know, it's correct or not.
can you please check it.

bool OpenIPMPDOIContentInfoManager::ParseHostIPPort(const std::string& hostURL,
    std::string& hostIP, int& hostPort) {
  const char* colon = strchr(hostURL.data(), ':');
  if (colon == NULL) {
    return false;
  }
  
	std::string::iterator p;
	*p = *colon;
   hostIP = std::string(hostURL.begin(),p);
  hostPort = atoi(colon+1);
  return true; 

please give me suuggestion. Will this code work or not.
Thanks

[Peter87]

No that code is not correct.

std::string::iterator p; // p is not referring to a valid element
*p = *colon;             // so you should not try to dereference it.
                         // This is similar to how normal pointers work:
                         // You should not dereference dangling
                         // pointers and null pointers. 

[mini20071985]

ohh, then please suggest me something. Because this code is compiling, that means the solution would be something like this only. Please suggest something.

[Peter87]

I have already suggested something that should work but you said it didn't work. http://ideone.com/Zs6V7

[mini20071985]

hey Peter, thanks buddy.

It;s working now. cheers!!!!!

I made two changes, first i added two new headers
#include <cstring>
#include <cstdlib>

and then i change hostURL. begin() to hostURL.data().

Now it's working. Thanks alot. You did it. Thanks :)