Initializing an array of empty vectors

Question

I'm trying to create an array of empty string vectors, but I can't manage to initialize the vectors to be able to push values into them:

vector <string> v[500];
// vector initializing code
v[0].push_back("hello"); // should work now

Error message is:

'v' does not name a type

How should I initialize so that v[0].push_back() works?

What isn't working for you at the moment? Your current problem description is unclear. **EDIT:** Your code works as is. Demo: [here](https://ideone.com/fLXQ82). — Algirdas Preidžius, Nov 29 '16 at 15:19
That should work. `vector v[500]` should initialize vectors to empty. — EmDroid, Nov 29 '16 at 15:20
Nothing to do, vector will be initialize correctly ([demo](http://coliru.stacked-crooked.com/a/dca3bb0eb954d8cf)). By, why not using vector of vector ? (`vector> v(500)`) — Garf365, Nov 29 '16 at 15:21
Or better, if size is known at compime-time : `std::array, 500> v;` — informaticienzero, Nov 29 '16 at 15:22
Regarding the update with error message, did you `#include` relevant headers? — Algirdas Preidžius, Nov 29 '16 at 15:22
According your edit, your issue isn't with vector initialization, but with declaration! have you include `vector` ? `string` ? have you somewhere `using namespace std;` ? — Garf365, Nov 29 '16 at 15:22
I'm placing my bet on `v[0].push_back("hello");` not being inside a function. — Quentin, Nov 29 '16 at 15:25
+Garf365 I considered vector of vectors but I wanted to know why array of vector's doesn't work, +Algirdas Preidzius, +Garf365 all #include are included as is using namespace std — byrass, Nov 29 '16 at 15:26
Also, while you're at it, remove that `using namespace std;`. It's a horribly bad practice. — Quentin, Nov 29 '16 at 15:27
@byrass is `v[0].push_back("hello");` written inside a `main` function? — Algirdas Preidžius, Nov 29 '16 at 15:27
vector has dynamically allocated memory why it should have size in initialization ? — Adib, Nov 29 '16 at 15:29
@byrass So, that's your problem. You cannot have executable code outside of functions. If you are having these sorts of problems, I suggest you read a book on C++. — Algirdas Preidžius, Nov 29 '16 at 15:31

score 1 · Accepted Answer · edited Jun 09 '19 at 04:03

As pointed in all the comments on your question, your error occurs because you wrote your code out of a main function. Each C++ program must have it.

By the way, here are good practices for free (found also in comments).

Use std::array instead of C-array if you know the size at compile-time (and I believe you do).
Avoid using namespace std; because it's bad.
Be sure that you do well all your includes : #include <string>, #include <vector> and #include <array> if using-so.
If you're a C++ beginner, I suggest C++ Primer, updated for C++11. If your a complete beginner, Programming: Principles and Practice Using C++.

Initializing an array of empty vectors

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