segmentetion fault......again.

[tsilis3]

About five days ago i posted here a piece of code that produced a segfault. After using the advices from some members the code worked but now its giving a segfault again for a different set of data. I cant understand why its working for one set and not for the other so i m reposting the code in case some of you can see other mistakes in it.

//slots creation
	 bool nodeinscs,nodedestinrcs;
	 int counter=0;
    list<nodes> nodelist;
    list<nodes>::iterator tempnode,e,u; 
    list<int> reccolset;
	list<int> sendcolset;
	list<int>::iterator s,m,b;
	list<int> recnodes;
	list<int> sendnodes;
	d=0;
	for(i=0;i<n;i++){
                     nodelist.push_front(nodearr[i]);
                     }
     do {  
           cout<<"newslot"<<endl;
           reccolset.clear();
           sendcolset.clear();
           sendnodes.clear();
           recnodes.clear();    
		   for(e=nodelist.begin();e!=nodelist.end();++e){//nodelist loop
			   nodeinscs=false;
			   nodedestinrcs=false;
              for(b=sendcolset.begin();b!=sendcolset.end();++b){
				if(e->nid==*b)
				        {
							nodeinscs=true;  	
						  }
				}
				for(m=reccolset.begin();m!=reccolset.end();++m){
					if(e->dest==*m)
					    {
							nodedestinrcs=true;
						}
					}
					if(e->recv==0&&nodeinscs!=true&&nodedestinrcs!=true)
	                                  {
										  counter++;
										  cout<<"counter++"<<endl;				
										  sendnodes.push_front(e->nid);
										  recnodes.push_front(e->dest);
										  for(u=nodelist.begin();u!=nodelist.end();u++)
                                          {
                                                     if(u->nid==e->dest){
														  cout<<"GGG"<<endl;
                                                          u->recv--;
                                                          }
                                          }                                                 
										  //filling collison sets:
                                          sendcolset.push_back(e->dest);
										  s=e->neighbors.begin();
										  for(i=0;i<e->non;i++)
										                {
															cout<<"LLLL"<<endl;
											  reccolset.push_back(*s);
											  s++;
										                 }
											m=nodearr[e->dest].neighbors.begin();        
											for(i=0;i<=nodearr[e->dest].non;i++)
											          {			 
													 sendcolset.push_back(*m);
													 cout<<"HHH"<<endl;
													 m++;
												 }
												e=nodelist.erase(e);
										  }
							}
							cout<<"nodes for send  "<<endl;
					        for(s=sendnodes.begin();s!=sendnodes.end();++s){
		                    cout<<"  "<<*s;
								  }
					        cout<<"nodes for receive  "<<endl;
					        for(s=recnodes.begin();s!=recnodes.end();++s){
					     	cout<<"  "<<*s;
						    		      }			
					}while (counter<n);
					//edo tha ginei print to slot
					  
cout<<"ssssssssss";
 wait(10000);
}

[daviddoria]

Maybe you can post a complete, compilable example, as well as the input that it is segfaulting with.

Dave

[PanGalactic]

You didn't take the earlier advice to refactor this into smaller functions. This is a very large function with insane indentation. Of course it will have problems.

My advice: break it up into smaller chunks. The problem will be easier to track down.

Try keeping functions to no more than 20 lines and no more than 3 levels of indentation. What this does is reduce the Cyclomatic Complexity of a function. http://en.wikipedia.org/wiki/Cyclomatic_complexity

It would also help to use a cleaner coding style. Style and legibility really does matter.

[tsilis3]

Ok. I took PanGalactic's advice and for the past two days i've been trying to divide my code into smaller functions. It has actually been really helpful since it is a lot easier to debug it now. The next problem i have to deal with is the following: I need to make a function in order to retrieve the data for the algorithm. I this function i'm declaring an array of type "nodes" which is a structure of integer values. This array is necessary for some other functions in my code but when i try to compile the program i get errors saying the array was not declared or something like that. Is it possible to do this? If so can you give me any advice on how to?