Printing data in a vector

Question

I havent done C++ in a while.

Im trying to get a vector of vectors to print data. I get the following error:

Segmentation fault (core dumped)

I am using an online complier to run the code.

#include <iostream>     // std::cout
#include <algorithm>    // std::for_each
#include <vector>       // std::vector

void myfunctiontwo (int i) {  // function:
  std::cout << ' ' << i;
}

void myfunction (std::vector<int> myvector) {  // function:
  for_each (myvector.begin(), myvector.end(), myfunctiontwo);
}

int main () {
  // create a vector of vectors. 
  std::vector< std::vector<int> > myvector; 

  // add some data
  myvector[0].push_back(10); 
  myvector[1].push_back(20);
  myvector[2].push_back(30);

  std::cout << "myvector contains:";
  for_each (myvector.begin(), myvector.end(), myfunction);
  std::cout << '\n';

  return 0;
}

@PoiXen: Yep, sorry, I was blind. But have a look a the [pretty printer](http://stackoverflow.com/q/4850473/596781) :-) — Kerrek SB, May 22 '13 at 08:48

score 3 · Accepted Answer · answered May 22 '13 at 08:47

3

Your problem is the pushing back:

myvector[0].push_back(10); 
myvector[1].push_back(20);
myvector[2].push_back(30);

The vectors myvector[0], myvector[1], and myvector[2] do not yet exist. If you want myvector to begin with 3 vectors, you can create it like so:

std::vector< std::vector<int> > myvector(3);

answered May 22 '13 at 08:47

Joseph Mansfield

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Better yet, `myvector = { { 10 }, { 20 }, { 30 } }` :-) – Kerrek SB May 22 '13 at 08:48
@KerrekSB Yep. I suspect from the way they format their template arguments that they're using C++03, though. – Joseph Mansfield May 22 '13 at 08:49

score 0 · Answer 2 · answered May 22 '13 at 09:44

0

as you can see from the following link http://www.cplusplus.com/reference/vector/vector/operator[]/, operator[] is Access element tha's way you can't insert element with it. to insert objects use Assign , push_back and insert

answered May 22 '13 at 09:44

beyrem

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Printing data in a vector

2 Answers2