c++ STL：关于 std::vector 的移除删除函数remove()和erase()的使用

一、结论

std::vector 中remove（）只是将待删除元素之后的元素移动到vector的前端，而不是真正删除。若要真正移除，需要搭配使用erase()。

二、论证代码

#include 
#include 
using namespace std;

int main()
{
	const int VECTOR_SIZE = 8;

	// Define a template class vector of integers
	vector<int > Numbers(VECTOR_SIZE);

	//Initialize vector Numbers
	Numbers[0] = 10;
	Numbers[1] = 20;
	Numbers[2] = 10;
	Numbers[3] = 15;
	Numbers[4] = 12;
	Numbers[5] = 7;
	Numbers[6] = 9;
	Numbers[7] = 10;

	cout << "The Numbers:" << endl;

	for (auto itor : Numbers)
	{
		cout << itor << "  " ;
	}

	cout << endl;
	cout << "After remove() The Numbers:" << endl;
	auto itorLast = remove(Numbers.begin(), Numbers.end(), 10);
	for (auto itor : Numbers)
	{
		cout << itor << "  ";
	}

	cout << endl;
	cout << "After remove() The removed Number count:" << Numbers.end() - itorLast << endl;
	cout << "After remove() The wanted Numbers:" << endl;
	for (auto itor = Numbers.begin(); itor != itorLast; itor++)
	{
		cout << *itor << "  ";
	}
	
	return 0;
}
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三、真正实现删除

#include 
using namespace std;
#include 
int main()
{
	const int VECTOR_SIZE = 8;

	// Define a template class vector of integers
	vector<int > Numbers(VECTOR_SIZE);

	//Initialize vector Numbers
	Numbers[0] = 10;
	Numbers[1] = 20;
	Numbers[2] = 10;
	Numbers[3] = 15;
	Numbers[4] = 12;
	Numbers[5] = 7;
	Numbers[6] = 9;
	Numbers[7] = 10;

	cout << "The Numbers:" << endl;

	for (auto itor : Numbers)
	{
		cout << itor << "  " ;
	}
	cout << endl;

	Numbers.erase(remove(Numbers.begin(), Numbers.end(), 10), Numbers.end());
	for (auto itor : Numbers)
	{
		cout << itor << "  ";
	}

	return 0;
}
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四、关于erase()使用误区

错误用法：earase()结束后，iter变成了野指针，iter++就产生了错误。

for(vector<int>::iterator iter=veci.begin(); iter!=veci.end(); iter++)
{
      if( *iter == 3)
      {
      	  veci.erase(iter);
      }    
}
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另一种错误：无法删除连续两个3.

for(vector<int>::iterator iter=veci.begin(); iter!=veci.end(); iter++)
{
      if( *iter == 3)
             iter = veci.erase(iter);
}
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正确用法：

for(vector<int>::iterator iter=veci.begin(); iter!=veci.end(); )
{
     if( *iter == 3)
          iter = veci.erase(iter);
      else
            iter ++ ;
}
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五、对于有序数组去重

// 先排序
sort(Numbers.begin(), Numbers.end());
// 去除重复
Numbers.erase(unique(Numbers.begin(), Numbers.end()), Numbers.end());
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