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IP address of a Host

Posted on 2001-06-06
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Last Modified: 2013-11-20
hi all
i want to get the IP address of a host connected in a network.
i tried a sample program but it gives me an error
saying error getting local hostname.
i want to use it my application.
 for testing purpose i wrote in C.


can any one give the solution to my problem


#include <iostream.h>
#include <Winsock2.h>
 
int main()
{
struct in_addr addr;
   struct hostent *phe;
   char ac[80];
   int i;
   char  *local;
   
   // get the name of the local host
  if (gethostname(ac, sizeof(ac)) == SOCKET_ERROR) {
      printf("Error getting local host name: %d\n",WSAGetLastError());
      return 1;
   }
   printf("Host name is %s\n",ac);
   
   phe = gethostbyname(ac);  
   if (phe == 0) {
      cout << "Error:  Bad host lookup." << endl;        
   return 1;
   }    
   for (i=0; phe->h_addr_list[i] !=0; ++i) {        
      memcpy(&addr, phe->h_addr_list[i],sizeof(struct in_addr));
      printf("Card %i) %s\n",i,inet_ntoa(addr));
      local=inet_ntoa(addr);
   }  
}
0
Comment
Question by:navyareddy
  • 8
9 Comments
 
LVL 32

Accepted Solution

by:
jhance earned 30 total points
ID: 6159095
You are NOT checkeding the ERROR code returned by the gethostname() function.  If you did, you'd see that it is saying WSANOTINITIALISED.  This means:

A successful WSAStartup call must occur before using this function. (to quote the SDK)

Call WSAStartup() BEFORE calling the gethostname function and call WSACleanup BEFORE ending your application.

Try:

#include <iostream.h>
#include <Winsock2.h>
 
int main()
{
struct in_addr addr;
  struct hostent *phe;
  char ac[80];
  int i;
  char  *local;

  WORD wVer = MAKEWORD(1, 1);
  WSADATA ws;


  if (WSAStartup(wVer, &ws) != 0){
    printf("Error in WSAStartup\n");
    return 1;
  }
 
  // get the name of the local host
 if (gethostname(ac, sizeof(ac)) == SOCKET_ERROR) {
     printf("Error getting local host name: %d\n",WSAGetLastError());
     WSACleanup;
     return 1;
  }
  printf("Host name is %s\n",ac);
 
  phe = gethostbyname(ac);  
  if (phe == 0) {
     cout << "Error:  Bad host lookup." << endl;        
  return 1;
  }    
  for (i=0; phe->h_addr_list[i] !=0; ++i) {        
     memcpy(&addr, phe->h_addr_list[i],sizeof(struct in_addr));
     printf("Card %i) %s\n",i,inet_ntoa(addr));
     local=inet_ntoa(addr);
  }  
  WSACleanup()
}
0
 

Author Comment

by:navyareddy
ID: 6159312
thanks its working fine.
0
 
LVL 32

Expert Comment

by:jhance
ID: 6159645
>>thanks its working fine.

In that case, it's customary to ACCEPT the answer and close this question.
0
 
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Expert Comment

by:jhance
ID: 6161292
Hello????
0
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Expert Comment

by:jhance
ID: 6161833
Hello?
0
 
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Expert Comment

by:jhance
ID: 6162276
Hello?????
0
 
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Expert Comment

by:jhance
ID: 6163283
Hello????????????????????????????????????????????????????????????????????????????????????/
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Expert Comment

by:jhance
ID: 6165084
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0
 
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Expert Comment

by:jhance
ID: 6167461
>>>and have been rewarded with a grade of B.

What an INGRATE!!!  Not only did I explain what you were doing wrong I correct your code!!!

Don't expect to receive help from me in the future!@
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