I can't add item to ( std::vector < std::vector > )

Question

Why can't I add an item to vector :

std::vector < std::vector <std::string> > my_list;
my_list[0][0] = "this is text";

std::cout << "text: " << my_list[0][0] << std::endl;

What am I doing wrong?

When you create a vector it is empty. ***All*** indexing into it will be out of bounds. Perhaps you should [get a good beginners book or two](http://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list)? — Some programmer dude, Dec 07 '17 at 11:54
You need to init all the vectors inside the vector of vectors. — JLev, Dec 07 '17 at 11:54

score 0 · Accepted Answer · answered Dec 07 '17 at 11:56

Unlike some containers (such as std::map), a std::vector does not grow on demand.

So before you index an element you need to make sure the std::vector has the appropriate size. You can do that by passing a size on construction.

In your case you could use the flashy syntax

std::vector < std::vector <std::string> > my_list{{"this is a test"}};

to get things going.

1 Answers1