C++ 删除向量中的对象

Question

我目前正在使用一个矢量来将人们固定在一个程序中。我正在尝试用

删除它

vectorname.erase(index);

我在函数中传递了向量，以及我要删除的元素。我的主要问题是如何在编译速度方面提高我的代码？

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

class person {
    private:
        string name;
    public:
        person() {}
        person(string n):name(n){}
        const string GetName() {return name;}
        void SetName(string a) { name = a; }
};

void DeleteFromVector(vector<person>& listOfPeople,person target) {
    for (vector<person>::iterator it = listOfPeople.begin();it != listOfPeople.end();++it) {//Error 2-4
        if (it->GetName() == target.GetName()) {
            listOfPeople.erase(it);
            break;
        }
    }
}

int main(){
    //first group of people
    person player("Player"), assistant("Assistant"), janitor("Janitor"), old_professor("Old Professor");

    //init of vector
    vector<person> listOfPeople = { player, assistant, janitor, old_professor };

    DeleteFromVector(listOfPeople, janitor);
}

Answer 1

无需定义index，迭代器可用于访问vector中的对象：

for (vector<person>::iterator it = listOfPeople.begin(); it != listOfPeople.end(); ++it) {//Error 2-4
    if (it->GetName() == target.GetName()) {
        listOfPeople.erase(it);
        break;
    }
}

Since next line is to break for loop, we don't consider invalid iterator problem here.

Answer 2

您不需要该循环来从向量中删除对象。只需使用 std::find_if:

#include <algorithm>
//...
void DeleteFromVector(vector<person>& listOfPeople, const person& target) 
{
    // find the element
    auto iter = std::find_if(listOfPeople.begin(), listOfPeople.end(),
                             [&](const person& p){return p.GetName() == target.GetName();});

    // if found, erase it
    if ( iter != listOfPeople.end())
       listOfPeople.erase(iter);
}

Answer 3

listOfPeople.erase(
                   remove(listOfPeople(), listOfPeople.end(), target),
                   listOfPeople.end()
                  )

"remove" erase-remove idiom 中的操作会将除 target 之外的所有元素移动到向量范围的前面，"erase" 操作将删除末尾满足目标标准。这是非常有效的，即使它不像迭代版本那样具有表现力。

C++ 删除向量中的对象

C++ Deleting an object in a vector

c++

vector

visual-studio-2015

erase