swap elements of vector

[chiefsosa1]

hello, i need to learn how to swap the first and 'mid' elements of a vector? can anybody help?

[Mats]

Find the size of the vector and once you have that, find the middle number (what are you supposed to do if the vector size is an even number and there are two middle elements?). Then swap this number with the first. <vector> already has functions to find the size and swap elements can be done by just copying the values to some place else then inserting them back in appropriate places afterwards - http://www.cplusplus.com/reference/vector/vector/

[chiefsosa1]

im trying to figure out how to use this 'swap' function. it sounds like it swaps elements of two different vectors, and now to elements that are inside of the same vector? or maybe im just not understanding