正确使用stl vecotr erase函数

erase函数要么删作指定位置loc的元素,要么删除区间[start, end)的所有元素.

返回值是指向删除的最后一个元素的下一位置的迭代器

Parameters

All parameters are of member type iterator, which in vector containers are defined as a random access iterator type.

position

Iterator pointing to a single element to be removed from the vector.

first, last

Iterators specifying a range within the vector to be removed: [first,last). i.e., the range includes all the elements between first and last, including the element pointed by first but not the one pointed by last.

Return value

A random access iterator pointing to the new location of the element that followed the last element erased by the function call, which is the vector end if the operation erased the last element in the sequence.

删除值为3的元素，按说it = vec.erase(it); 是正确的，但是我实验发现 it = vec.erase(it);和 vec.erase(it);都可以work，没有crash。

#include <iostream>
#include <vector>

using namespace std;

int main()
{
    vector<int> vec;
    vec.push_back(1);
    vec.push_back(2);
    vec.push_back(3);
    vec.push_back(4);
    vec.push_back(5);

    for(vector<int>::iterator it = vec.begin(); it != vec.end(); it++)
    {
        if(*it == 3)
        {
            it = vec.erase(it);
            //vec.erase(it);
            cout << *it << "CCC" << endl;
            it --;
        }
        else
            cout << *it << endl;
    }
    return 0;
}

//注意上面不能写成

/*
        for(vector<int>::iterator it=arr.begin(); it!=arr.end(); it ++)
        {
            if(* it == 8)
            {
                arr.erase(it); //在erase后，it失效，并不是指向vector的下一个元素，it成了一个“野指针”。

}
        }
      
    */