c++ - c++ myVector.erase(myVector.begin())有效但在我的对象中无效

我的ptBucket.getBucket（）。at（icnt）如何工作，但是我的ptBucket.getBucket（）。erase（）和ptBucket.getBucket（）。begin（）无法工作。
代码如下。

我想要一个包含指针向量的对象。指针将指向动态分配的对象，最后我要清理。我似乎正在搞砸间接的额外水平。

#include <iostream>
#include <string>
#include <vector>
#include <sstream>
#include <stdio.h>
#include <stdlib.h>

using namespace std;


class Pt{
int x_;
int y_;
public:
  Pt(int x, int y);
  int getX();
  int getY();
};// end class pt

Pt::Pt(int x, int y){
x_ = x;
y_ = y;
}

int Pt::getX(){
return x_;
}

int Pt::getY(){
return y_;
}

class BucketOfPts{
vector<Pt*>bucket;
public:
void addToBucket(Pt *pt);
vector<Pt*> getBucket();
};

void BucketOfPts::addToBucket(Pt *pt){
bucket.push_back(pt);
}

vector<Pt*> BucketOfPts::getBucket(){
return bucket;
}

int main()
{

cout << "this works" << endl;
vector<Pt*> points;
for(unsigned icnt =0;icnt<5;icnt++)
    points.push_back(new Pt(icnt,icnt));
for(unsigned icnt =0;icnt<5;icnt++)
    cout << "x of icnt["<<icnt<<"] "<< points.at(icnt)->getX() << endl;
for(unsigned icnt =0;icnt<5;icnt++)
    {
    /*** this simple construct does work ***********/
    points.erase(points.begin());
    /*** this simple construct does work ***********/
    cout << "size: " << points.size() << endl;
    }

cout << "this does NOT work" << endl;
BucketOfPts ptBucket = BucketOfPts();
for(unsigned icnt =0;icnt<5;icnt++)
    ptBucket.addToBucket(new Pt(icnt,icnt));
for(unsigned icnt =0;icnt<5;icnt++)
    cout << "x of icnt["<<icnt<<"] "<< ptBucket.getBucket().at(icnt)->getX() << endl;


// how come ptBucket.getBucket.at() above works
// but ptBucket.getBucket.begin() below does not work??

cout << "going to try to erase" << endl;
for(unsigned icnt =0;icnt<5;icnt++)
    {
    cout << "going to erase icnt: " << icnt << endl;
    /*** this simple construct does NOT work ***********/
    ptBucket.getBucket().erase(ptBucket.getBucket().begin());
    /*** this simple construct does NOT work ***********/
    cout << "size: " << ptBucket.getBucket().size() << endl;
    }
return 0;

}

    here's my output:

    this works
    x of icnt[0] 0
    x of icnt[1] 1
    x of icnt[2] 2
    x of icnt[3] 3
    x of icnt[4] 4
    size: 4
    size: 3
    size: 2
    size: 1
    size: 0
    this does NOT work
    x of icnt[0] 0
    x of icnt[1] 1
    x of icnt[2] 2
    x of icnt[3] 3
    x of icnt[4] 4
    going to try to erase
    going to erase icnt: 0
    Segmentation fault (core dumped)

最佳答案

照原样，您的getBucket()函数将返回vector<Pt*> bucket;成员的副本。因此，声明

ptBucket.getBucket().erase(ptBucket.getBucket().begin());

只能使用该向量的两个不相关的副本进行操作。

要使类实例中的vector成员受影响，您需要返回对此成员的引用

class BucketOfPts{
public:
    // ...
vector<Pt*>& getBucket();
        // ^ <<<<<<
};

vector<Pt*>& BucketOfPts::getBucket() {
        // ^ <<<<<<
    return bucket;
}

`