erase element from vector

[eliranko]

say I have a vector with 8(0-7) elements.
How do I delete the 4th element?

vec.erase(vec.begin() +4);

or

vec.erase(vec.begin() +3);

I've seen this code:

  // erase the 6th element
  myvector.erase (myvector.begin()+5);

  // erase the first 3 elements:
  myvector.erase (myvector.begin(),myvector.begin()+3);

in the second line they remove the 6th element by adding 5 to vec.begin()
but in the last line they add +3 to delete the first 3 elements. I got a bit confused there,so I decided to ask you guys :)

[freddy92]

In the second line, myvector.begin()+0 would be the 1st element, +1 would be the 2nd, +2 the 3rd, and so on. So to access the 4th element, it would be myvector.begin()+3.

In the last line, this is calling a different version of the same function (one that takes 2 parameters). The first parameter is the element to start at, while the second parameter is the element after the last one you want erased. So it will erase everything from the 1st element up to the 4th element, which is the first 3 elements.