我有一个错误的分配,我得到一个seg错误,当读取核心转储给出这个:
#0 0xb781eb27 in std::basic_string<char, std::char_traits<char>, std::allocator<char> >::size() const () from /usr/lib/libstdc++.so.6
这是我认为它所指的代码段。
bool flightmap::GetNextCity(int& index, int& nextCity){
bool success = false;
flightRec tmp, tmp2;
for (int i = nextCity; (!success) && (i < size); i++)
{//if Citytmp goes over size, we never found it
tmp.DestinationCity = GetCityName(i);
tmp2 = map[index].Retrieve(tmp,success);
}//end for loop
if (success)
{
nextCity = GetCityNumber(tmp2.DestinationCity);
}//end if
return success;
}
这是检索功能:
flightRec sortedListClass::Retrieve(flightRec& input, bool& success) const{
nodeptr curr;
flightRec tmp;
curr = head;
if (head == NULL)
{//If the list is empty
std::cout << "List empty, operation not preformed" << std::endl;
success = false;
}
/*LINE 167*/ while ((curr!=NULL)&&(!(curr->DestinationCity==input.DestinationCity))) //<- THIS IS LINE 167
{//Here we first check if curr points to NULL, then we see if DesinationCity and Origin are not yet found.
curr=curr->ptr;
}
if ((curr->DestinationCity==input.DestinationCity))
{//If we found it, then let's return it...
tmp.DestinationCity=curr->DestinationCity;
//tmp.Origin=curr->Origin;
tmp.flightnumber=curr->flightnumber;
tmp.cost=curr->cost;
success = true;
return tmp;
}
else //We didn't and then...damn.
{
//std::cout << "Can't find flight to " << input.DestinationCity << std::endl;
success = false;
}
}
flightRec:
struct flightRec{
std::string Origin;
int flightnumber;
float cost;
std::string DestinationCity;
bool operator <(const flightRec& rhs) const;
bool operator ==(const flightRec& rhs) const;
flightRec* ptr;
};
typedef flightRec* nodeptr;
flightMap.h
#ifndef FLIGHTMAP_H
#define FLIGHTMAP_H
#include "sortedListClass.h"
#include "stackClass.h"
#include <fstream>
#include <cstdio>
class flightmap {
public:
flightmap();
flightmap(const flightmap& orig);
virtual ~flightmap();
void readcities (std::ifstream& in);
void readflights (std::ifstream& in);
void display ();
void isPath (int& in, int& out);
void MarkVisited (int& index);
bool IsVisited (int& index);
void UnvisitAll ();
bool GetNextCity (int& index, int& nextCity);
int GetCityNumber(std::string& city);
std::string GetCityName(int& index);
private:
int size;
sortedListClass* map;
std::string* origin;
bool* visited;
};
#endif
在gdb中键入bt之后,这就是输出:
#0 0xb7f4eb27 in std::basic_string<char, std::char_traits<char>, std::allocator<char> >::size() const () from /usr/lib/libstdc++.so.6
#1 0x0804a407 in std::operator==<char> (__lhs=..., __rhs=...) at /usr/lib/gcc/i686-pc-linux-gnu/4.5.2/../../../../include/c++/4.5.2/bits/basic_string.h:2345
#2 0x0804ab32 in sortedListClass::Retrieve (this=0x8053468, input=..., success=@0xbffff0a3) at sortedListClass.cpp:167
#3 0x0804a1ff in flightmap::GetNextCity (this=0xbffff4dc, index=@0xbffff108, nextCity=@0xbffff104) at flightMap.cpp:197
#4 0x08049ba7 in flightmap::isPath (this=0xbffff4dc, in=@0xbffff164, out=@0xbffff160) at flightMap.cpp:110
#5 0x08049314 in FindPath (datafile=..., map=...) at ola6.cpp:51
#6 0x08049190 in main (argc=2, argv=0xbffff5b4) at ola6.cpp:35
答案 0 :(得分:1)
bt
对于回溯是正确的。您可以在sortedListClass::Retrieve
行167中看到错误开始。回溯中的下一个条目(返回到#0)是针对operator ==,这意味着第167行上的==是导致崩溃的原因
您发布的代码中有几个==调用,因此如果您可以编辑帖子并指出哪一行是第167行,我们可以进一步诊断。
添加行号后更新:
这只是一个猜测,但你可能忘记在程序早期的某个时刻将ptr
成员设置为NULL,以便最终在第167-168行的curr
周围指向随机内存位置,导致崩溃。此外,该内存位置的对象也可能已被释放,但ptr
尚未更新,并指向现在已删除的对象。仔细检查您的代码,分配新flightRec
个对象的位置,并确保始终正确设置ptr
。
答案 1 :(得分:0)
代码中声明/定义的size
在哪里?
看起来你最终会被称为std :: basic_string size
方法。