Vector remove 2 numbers at the same time

[ballinlinda]

I want to remove 2 numbers at the same time without using literals

#include <iostream>
#include <vector>

using namespace std;

int main()
{
	vector<int> v;
	
	for(int i = 1;i <= 10;i++)
	{
		v.push_back(i);
	}
	
	int beg = 0;
	int end = v.size() - 1;
	
	for(int i = end;i >= beg;i--)
	{	//remove 5 and also remove something other number
		if(v[i] == 5)
		{
			//remove 5 and 3 at same time
			v.erase(v.begin()+i);
			v.erase(v.begin()+2); // i remove 3 but 2 is a literal which i dont want to use
		}
	}
	
	for(int i = 0; i < v.size();i++)
	{
		cout << v[i] << " ";
	}
	
	return 0;
}

[keskiverto]

That is not exactly "remove 5 and 3 at same time".

It is more like:

IF there is element with value 5
THEN remove that element and the third element of the vector

Furthermore, the "if there is" seeks the vector in reverse order.

You do already have two issues:

* If the last element has value 5, then the vector shrinks by two elements, but the 'i' only by one. Next iteration does thus v[v.size()], which is out of range error.

* What if vector has size 3 and the last value is 5? After erasing that you try to erase the third element of size 2 vector. Out of range error.


You do probably have some reason to erase the third element. The third element is literally the third, there is no way around that. Are you just trying to avoid some other problem with the "without literals" idea?

[ballinlinda]

v.erase(v.begin()+i);
v.erase(v.begin()+2);

instead of doing +2 from the beginning

from the position where 5 was located

i want to remove a cell 2 cells after and before

so in case
where ever the 5 is i want to remove 2 cells after and before
if 5 is at the end i will put a case for that like "if(i == v.size()-1)"

[ballinlinda]

ISSUES ARE FIXED
just changed the borders
even if i dont scan through the whole vector 7 8 9 10 are still there

#include <iostream>
#include <vector>

using namespace std;

int main()
{
	vector<int> v;
	
	for(int i = 1;i <= 10;i++)
	{
		v.push_back(i);
	}
	
	int beg = 2;
	int end = v.size() - 4;
	
	for(int i = end;i >= beg;i--)
	{	
		if(v[i] == 5)
		{
			//remove 5 and 3 at same time
			v.erase(v.begin()+i);
			v.erase(v.begin()+2);
		}
	}
	
	for(int i = 0; i < v.size();i++)
	{
		cout << v[i] << " ";
	}
	
	return 0;
}

[Manga]

How about this?

#include <iostream>
#include <vector>

using namespace std;

int main()
{
	vector<int> v;
	
	for(int i = 1;i <= 10;i++)
	{
		v.push_back(i);
	}
	
	int beg = 0;
	int end = v.size() - 1;
	
	for(int i = end;i >= beg;i--)
	{	//remove 5 and also remove something other number
		if(v[i] == 5 || v[i] == 3)
		{
			//remove 5 and 3 at same time
			v.erase(v.begin() + i);
			i = v.size() - 1; //restart the loop
		}
	}
	
	for(int i = 0; i < v.size();i++)
	{
		cout << v[i] << " ";
	}
	
	return 0;
}