Question

我想从矢量中删除对象。矢量通过引用传递，我迷路了。我已经尝试过brickList.erase（它）以及组合擦除删除，但我无法弄清楚正确的表达式。

有人会这么善意帮我评论一下吗？在一般情况下，让我们说100块砖随机位置。

#include "stdafx.h"

#include <iostream>
#include <vector>

class Brick {
private:
    int position;
public:
    Brick(int);
    int getPosition();
};
Brick::Brick(int p) : position(p) {};
int Brick::getPosition() { return position; }

void removeBricks(int a, int b, std::vector<Brick> &brickList) {
    std::vector<Brick>::iterator it;
    for (it = brickList.begin(); it != brickList.end(); ++it) {
        int currentPos = (*it).getPosition();
        if (currentPos >= a && currentPos <= b) {
            // here I need help to delete objects
        }
    }
}

int _tmain(int argc, _TCHAR* argv[])
{
    std::vector<Brick> myBricks;
    for (int i = 0; i<10; ++i) {
        Brick tmp_brick(i);
        myBricks.push_back(tmp_brick);
    }
    // delete all bricks with position between 3 and 5
    removeBricks(3, 5, myBricks);
    system("pause");
    return 0;
}

Answer 1

从您的代码中

// delete all bricks with position between 3 and 5
//removeBricks(3, 5, myBricks);  // <-- replace this
myBricks.erase(myBricks.begin()+3,myBricks.begin()+5); // <--  with this

使用基于范围的erase函数。您根本不需要removeBricks功能。

如果使用removeBricks()功能，您可以使用相同的函数原型进行此操作。

void removeBricks(int a, int b, std::vector<Brick> &brickList) {
    // check a >= 0, a < b and b doesn't exceed length of brickList
    brickList.erase(brickList.begin()+a,brickList.begin()+b);
}

编辑：似乎您的位置概念不是指您的项目的数组位置，而是Brick的成员函数的值。这应该适合你。

void removeBricks(int a, int b, std::vector<Brick> &brickList) 
{
    std::vector<Brick>::iterator it;
    for (it = brickList.begin(); it != brickList.end(); /* DONT increment here*/) {
        int currentPos = (*it).getPosition();
        if (currentPos >= a && currentPos <= b) {
            // store the return value from erase!!
            it = erase(it);
        }
        else
        {
            // increment here rather than in the for loop incrementer
            it++;
        }
    }
}

您必须存储erase的返回值，因为迭代器会失效。上面的内容应该对你有用，虽然vector不是容器的最佳选择，因为由于底层数组的重组，擦除项可能很慢。

c ++如何从函数中的向量中删除对象

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