option 4 crashes with a wrong input

[avnis]

it crashes after city not found
so here is the code
http://pastebin.com/Vgy5dKt5
if you run and read file of cities into it so maybe like if your file contained
Calgary 51.1 -114.0167
Vancouver 49.1833 -123.167
Winnipeg 49.9 -97.2333
Ottawa 45.3167 -75.6667
Moose_Jaw 50.3333 -105.55
and you enter that files names it load and then you choose option 4 and then enter a city that doesn't exist it crashes :|
how to fix it

[Mathes]

line 230 cout << cities[findLocation(citynm, cities)] << endl;
if you dont find the city, findLocation(...) will return -1, so you try to get cities[-1].
index out of bounds.

check the return value before you try to get the city, or use cities.at(), it will throw an exception if the position
is not valid.