将 shared_ptr 与向量一起使用时出现分段错误 [英] Segmentation fault on using shared_ptr with vectors
问题描述
我是第一次使用 shared_ptr,如果我犯了一个非常愚蠢的错误并帮助我克服这个分段错误,请原谅我.
I am using a shared_ptr for the first time pardon me If I have made a very silly mistake and help me in overcoming this segmentation fault.
我希望有一个私有的 vector
,即使对象被销毁,它也可以从不同的类中读取.因此我读到了 std::shared_ptr
I wish to have a private vector
which can be read from different classes even if the object is destroyed. Hence I read about std::shared_ptr
代码在 storeCounterData
函数中出现段错误
The code is giving a segfault in storeCounterData
function
预先感谢您的帮助!!!
Thanks in Advance for your help !!!
main.cpp
#include <iostream>
#include "counter.hpp"
#include "getCounter.hpp"
const int max_ports = 3;
int main()
{
Counter *counter = new Counter(3);
counter->age = 1;
counter->id = 12;
counter->pincode = 123;
std::vector<Counter*> counterData;
std::cout<<"inside main"<<std::endl;
counter->storeCounterData(counter,0);
counter->storeCounterData(counter,1);
counter->storeCounterData(counter,2);
std::cout<<"inside main calling getCounterData"<<std::endl;
counter->getCounterData(counterData);
Counter countji(3);
countji.getCounterData(counterData);
//getCounterData class function
getCounter *gcount = new getCounter();
gcount->printCounterData();
return 0;
}
计数器.hpp
#ifndef COUNTERHPP
#define COUNTERHPP
#include <vector>
#include <memory>
class Counter
{
private:
typedef std::shared_ptr<Counter> sharedCtr;
std::vector<sharedCtr> vecData;
public:
Counter();
Counter(int vecSize);
int age, id, pincode;
void storeCounterData(Counter *counter,int user);
void getCounterData(std::vector<Counter*> &counter);
};
#endif
计数器.cpp
#include "counter.hpp"
#include <iostream>
#include <vector>
Counter::Counter()
{
}
Counter::Counter(int vecSize):vecData(vecSize)
{
}
void Counter::storeCounterData(Counter *counter,int user)
{
vecData[user]->age = counter->age;
vecData[user]->id = counter->id;
vecData[user]->pincode = counter->pincode;
std::cout<<"vector size inside storeCounterData = "<<vecData.size()<<std::endl;
}
void Counter::getCounterData(std::vector<Counter*> &counter)
{
std::cout<<"vector size inside getCounterData = "<<vecData.size()<<std::endl;
for (auto& c : vecData)
{
std::cout << c->age << std::endl;
std::cout << c->id << std::endl;
std::cout << c->pincode << std::endl;
}
}
输出
火箭筒~/VECTOR$ ./a.out
Bazooka~/VECTOR$ ./a.out
内部主
分段错误(核心转储)
推荐答案
在 Counter
的构造函数中,您正在创建一个空 shared_ptr
向量,即没有托管Counter
的对象(见 (1) 此处).
In the Constructor of Counter
you are creating a vector of empty shared_ptr
s, i.e. there's no managed object of Counter
(see (1) here).
只需将行更改为:
Counter(int vecSize) : vecData(vecSize, std::make_shared<Counter>()) {}
您正在创建一个指针向量,因此我在这里看到了两个选项,用于您希望它的工作方式:
You are creating a vector of pointers, so I see two options here for the way you want it to work:
- 你这样做的方式:用 3 个
shared_ptr
实例化向量,但是你需要检查指针是否已经创建,每当你访问指针时.
- The way you did it: Instantiate the vector with 3
shared_ptr
s, but then you need to check if the pointer was already created, whenever you access the pointer.
也许这就是要走的路.shared_ptr
s 也是指针,你应该这样对待它们并始终检查有效性.
Maybe that's the way to go. shared_ptr
s are pointers aswell, you should treat them like that and always check for validity.
Counter(int vecSize) : vecData(vecSize) {} // previous constructor
void storeCounterData(Counter* counter, int user) {
if (!vecData[user]) {
vecData[user] = std::make_shared<Counter>();
}
vecData[user]->age = counter->age;
vecData[user]->id = counter->id;
vecData[user]->pincode = counter->pincode;
std::cout << "vector size inside storeCounterData = " << vecData.size()
<< std::endl;
}
void getCounterData(std::vector<Counter*>& counter) {
std::cout << "vector size inside getCounterData = " << vecData.size()
<< std::endl;
for (auto& c : vecData) {
if (c) {
std::cout << c->age << std::endl;
std::cout << c->id << std::endl;
std::cout << c->pincode << std::endl;
}
}
}
- 使用
std::vector::push_back
,这样向量中就只有有效"(你永远无法确定)shared_ptr
.立>
- Use
std::vector::push_back
, so that you only have "valid" (you never can be sure of this)shared_ptr
in the vector.
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