如何根据位置删除列表中的特定项目

Question

Example: I have a class of myClass which consists of 3 private attributes:

1. string itemName
2. float amount
3. string date

Then I create a list of myClass

list<myClass> mytemp;

In my mytemp I store a few items inside:

[ itemName ] [ amount ] [ date ]

1. myproductA 10 011214

2. myproductB 20 010115

3. myproductC 30 020115

4. myproductD 40 040115

I would like to delete myproductC

I currently have:

list<myClass>::iterator p=mytemp.begin();

//productC would be list(3)

p++; p++; p++;

//therefore remove:

mytemp.remove(p);

Am I right to say that? However p is an iterator, but list::remove wants a value.

How do I overcome this problem?

Answer 1

If you are sure that the target element in the list is the third element then instead of this code

list<myClass>::iterator p=mytemp.begin();

//productC would be list(3)

p++; p++; p++;

//therefore remove:

mytemp.remove(p);

You can replace it with this, if you are using C++11 or later:

mytemp.erase( std::next( mytemp.begin(), 2 ) );

Or this if you are using an older version:

list<myClass>::iterator p = mytemp.begin();
std::advance( p, 2 );
mytemp.erase( p );

To use std::next() or std::advance() , you need #include <iterator> .

As for the method remove() , it removes all elements of the list that are equal to a given value.

Answer 2

使用std::list::erase() 方法 。