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  1. #include <iostream>
  2. #include <vector>
  3.  
  4. std::ostream& operator<<(std::ostream& os, const std::vector<int>& v)
  5. {
  6.     os << '{';
  7.  
  8.     if (v.empty())
  9.         os << " empty";
  10.     else
  11.     {
  12.         for (auto e : v)
  13.             os << ' ' << e;
  14.     }
  15.  
  16.     return os << " }";
  17. }
  18.  
  19. std::ostream& operator<<(std::ostream& os, const std::vector<std::vector<int>>& v)
  20. {
  21.     for (auto e : v)
  22.         os << e << '\n';
  23.  
  24.     return os;
  25. }
  26.  
  27. int main()
  28. {
  29.     std::vector<std::vector<int>> row{ { 1 }, { 2 }, { 3 }, { 4 } };
  30.  
  31.     std::cout << row << '\n';
  32.  
  33.     row[0].erase(row[0].begin());
  34.  
  35.     std::cout << row << '\n';
  36. }
Success #stdin #stdout 0s 3276KB
comments (?)
stdin 
Standard input is empty
stdout 
{ 1 }
{ 2 }
{ 3 }
{ 4 }

{ empty }
{ 2 }
{ 3 }
{ 4 }
https://ideone.com/V0icCs
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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