C++代碼問題(segment fault)

#include <iostream>
#include <string>
#include <vector>
#include <set>
#include <map>
using namespace std;

/*int main()
{
	int a;
	a = 10;
	cout<<" "<<a<<endl;
	return 0;
}

*/
typedef struct com{
	string id;
	vector<string> subnode;
	vector<string> clid;
	set<string> nlid;
}comcross;

void init1(vector<comcross> &com_vec,map<string,vector<string> > &map_com);
void init2(vector<comcross> &com_vec, map<string,vector<string> > &map_com);

int main()
{
	vector<comcross> com_vec;
	map<string,vector<string> > map_com;
	init1( com_vec,map_com);
	init2( com_vec,map_com);
	
	for(vector<comcross> ::iterator iter = com_vec.begin();iter != com_vec.end();++iter)
	{
		for(set<string> ::iterator iter1 = iter->nlid.begin();iter1 != iter->nlid.end();++iter1)
		{
			cout<<" "<<*iter1;
		}	
	}
	system("pause");
	return 0;
}
void init1( vector<comcross> &com_vec,map<string,vector<string> > &map_com)
{

	string A[] = {"1","2","3","4"};
	string B[] = {"3","5","6","7"};
	string C[] = {"7","8","9","10"};
	string D[] = {"4","10","11","12"};
	//初始化map_com
	vector<string> tmp1(A,A+4),tmp2(B,B+4),tmp3(C,C+4),tmp4(D,D+4);

	map_com["A"]=tmp1;
	map_com["B"]=tmp2;
	map_com["C"]=tmp3;
	map_com["D"]=tmp4;
	//初始化com_vec
	comcross com;
	com.id = "A";
	string clid[]={"1","2","5","6","8","9","11","12"};
	vector<string> tmp5(clid,clid+8);
	com.clid = tmp5;
	
	string subnode[] = {"B","C","D"};
	vector<string> tmp6(subnode,subnode+3);
	com.subnode = tmp6;
	
	string nlid[] ={"1","2","3","4"}; 
	vector<string> tmp7(nlid,nlid+4);
	com.nlid.insert(tmp7.begin(),tmp7.end());

	com_vec.push_back(com);

}

void init2(vector<comcross> &com_vec, map<string,vector<string> > &map_com)
{
	vector<comcross>:: iterator iter = com_vec.begin();
	for(;iter != com_vec.end();++iter)
	{
		for(vector<string>:: iterator subiter1 = iter->subnode.begin();subiter1 != iter->subnode.end();++subiter1)
		{
			string subnodekey = *subiter1;
			map<string,vector<string> >::iterator mapit = map_com.find(subnodekey);
			if(mapit!=map_com.end()){
				iter->nlid.insert(mapit->second.begin(),mapit->second.end());			
			}
		}
	}

	for(iter = com_vec.begin();iter != com_vec.end();++iter)
	{
		for(vector<string> ::iterator subiter = iter->clid.begin();subiter != iter->clid.end();++subiter)
		{
			iter->nlid.erase(*subiter);			
		}
	}
}

輸出：

一、爲何set輸出不是順序的呢？？？？

C++ STL中標準關聯容器set, multiset, map, multimap內部採用的就是一種很是高效的平衡檢索二叉樹：紅黑樹，也成爲RB樹(Red-Black Tree)。map和set的樹創建之時就會自動排好序，

該set中字符串按照字典序排序，因此10排在3,4,7前面。。。

二、容器erase越界問題（Linux下segmentation fault(core dumped)問題）

容器erase操做以後返回下一個iterator，因此不要在循環內部作刪除操做。

通常都是由內存訪問越界形成的，無論是用戶態程序仍是內核態程序訪問越界都會出core。

在linux下通常使用gdb進行調試，避免這種問題就是在編寫程序時，使用規範的邏輯，和保證健壯性的判斷

小測試：

#include<stdio.h>
int main()
{
   int *p;
   *p=12;
   return 1;
}

在程序中對非法地址p進行寫操做，執行程序時顯示segmentation fault。

#include<stdio.h>
int main()
{
   int *p, temp;
   temp=*p;
   return 1;
}

在程序中對p指向地址進行 非法讀操做 ，執行時顯示segmentation fault。