Weird c++ program run error in two platforms

[csstudent123]

Hi. here is my code. It runs on Ubuntu perfectly fine. but when I run on mac OS X in both netbeans, codlin and Xcode the output is. this prog checks active/inactive IP in a network.

index 0 -> 192
first octet     //where is the value? it comes on ubuntu
2nd octet 168
ipCmnd .168.1.1
Checking if .168.1.1 is active or no
 /*If ping return 0 then IP is up else down*/

ping is ping -t 3 
ping is ping -t 3 .168.1.1
ping: cannot resolve .168.1.1: Unknown host
68
ipCmnd .168.1.2
Checking if .168.1.2 is active or no
 /*If ping return 0 then IP is up else down*/

ping is ping -t 3 
ping is ping -t 3 .168.1.2
ping: cannot resolve .168.1.2: Unknown host
68
ipCmnd .168.2.1
Checking if .168.2.1 is active or no
 /*If ping return 0 then IP is up else down*/

mycode

/*Platform Linux/Ubuntu
 ANSI C++11 ISO
 This program reads the network and displays active and inactive IPs
 */

#include <cstdlib>
#include <iostream>
#include <cstring>
#include <fstream>
#include <string>
#include <cstdio>
#include <unistd.h>
#include <sys/wait.h>

using namespace std;

int main()
{
    
    //Get the ip addresses from the network and write to file
    //system("ifconfig | grep 'inet addr:' | cut -d: -f2 | awk '{print $1}' > ipfile.txt");
    system("ifconfig en0 | grep inet | awk '{print $2}' > ~/desktop/ipfile.txt");
    
    string ipaddr="";
    ifstream rd;
    
    int ip_range[4]= {192,168,0,1}; //4 octets
    
    //open and read a IP address
    /*rd.open("/Users/ashari/desktop/ipfile.txt");
    if(rd.is_open()==true)
        cout<<"File Opened"<<endl;
    else{
        cout<<"File open fail"<<endl;
    return 0;}
    
    string lineignore;
    getline(rd, lineignore);
    
    while(rd>>ipaddr)
    {
        
        cout<<"Reading Surrounding Network "<<ipaddr<<endl;
        cout<<"Done"<<endl<<endl;
        
        
    }
    rd.close();
    
    //convert string IP to int IP
    char* tokens;
    char ip[(ipaddr.length())+1];
    int i=0;
    
    strcpy(ip, ipaddr.c_str());
    tokens= strtok(ip, ".");
    
    
    while(tokens!=NULL)
    {
        
        ip_range[i]=atoi(tokens);
        
        tokens=strtok(NULL,".");
        i++;
    }*/
    
    
    //initialise
    char ipCmd[100]="p", ipParse[100]="p";
    char firstOctet[3], secondOctet[3], thirdOctet[3], fourthOctet[3];
    //convert to char

    sprintf(firstOctet,"%d",ip_range[0]);
    sprintf(secondOctet, "%d",ip_range[1]);
    
    cout<<"index 0 -> "<<ip_range[0]<<endl;
    cout<<"first octet "<<firstOctet<<endl;
    cout<<"2nd octet "<<secondOctet<<endl;
    
    //loop through the network IPs to check active and inactive IPs
    
    for(int outerOct=1; outerOct<=2; outerOct++)
    {
        
        for(int innerOct=1; innerOct<=2; innerOct++)
        {
            //initialise ping command
            char ping[100]="ping -t 3 ";
            char success[]="; echo $?";//add at end of the command
            
            
            
            //copy IP octets to command
            strcpy(ipCmd,firstOctet);
            strcat(ipCmd,".");
            strcat(ipCmd,secondOctet);
            strcat(ipCmd,".");
            
            sprintf(thirdOctet, "%d",outerOct);
            strcat(ipCmd,thirdOctet);
            strcat(ipCmd,".");
            sprintf(fourthOctet, "%d",innerOct);
            strcat(ipCmd,fourthOctet);
            
            cout<<"ipCmnd "<<ipCmd<<endl;
            
            //get IP as chars
            strcpy(ipParse, firstOctet);
            strcat(ipParse,".");
            strcat(ipParse,secondOctet);
            strcat(ipParse,".");
            strcat(ipParse, thirdOctet);
            strcat(ipParse,".");
            strcat(ipParse, fourthOctet);
            
            cout<<"Checking if "<<ipParse<<" is active or no\n /*If ping return 0 then IP is up else down*/"<<endl<<endl;
            cout<<"ping is "<<ping<<endl;
            

            //build command
            strcat(ping,ipCmd);
            cout<<"ping is "<<ping<<endl;

            strcat(ping, success);
            
            
            system(ping);//execute ping
        }
        
        
    }
    
    return 0;
}

this same code I run in ubuntu and it works fine

what the heck is the prob??!!

thanks

[MiiNiPaa]

this same code I run in ubuntu and it works fine

Except that it does not. It just seems to work, but any future change, even recompilation may lead to problems.

You have undefined behavior here:

char firstOctet[3];
sprintf(firstOctet,"%d",ip_range[0]);

You defined firstOctet to store 3 chars, but you need 4 to represent all possible values for octet. So your stpintf call overruns buffer and then nobody can say what happens.

[csstudent123]

extra char for null...oohhh! thanks!

[keskiverto]

Why do you use compiled language at all? A shell script can achieve the same with less hassle.

If you do insist on using C/C++ (for educational purposes?), then you should not execute other binaries with system(). You should directly call the same system functions that the ifconfig and ping do.

[csstudent123]

ifconfig and ping is equivalent to which linux system call?

Thanks for the hint :)

[MiiNiPaa]

ifconfig and ping is equivalent to which linux system call?

ifconfig: Messing with ioctl calls.
ifconfig source: http://cvsweb.netbsd.org/bsdweb.cgi/src/sbin/ifconfig/ifconfig.c?rev=1.169&content-type=text/x-cvsweb-markup

ping: sending an icmp echo packet, obviously. Ping source: http://git.busybox.net/busybox/tree/networking/ping.c

[csstudent123]

thanks MINIpaa, but i wait till masters for this level :))