auto keyword type is not recognized in my pc

[atum100]

with the given code, my compiler does give an error saying that x has no type defined.

 void printGraph(vector<int> adj[], int V)
{
    for (int v = 0; v < V; ++v)
    {
        cout << "\n Adjacency list of vertex "
             << v << "\n head ";
        for (auto x : adj[v])
           cout << "-> " << x;
        printf("\n");
    }
}

[Thomas1965]

auto is a keyword that requires C++11 standard.
What compiler / IDE are you using?

[George P]

What exactly are you trying to do with the range-based for loop at line 7? Range-based for loops work with entire containers, not one specific element. An element has no container begin() statement associated with it.

MAJOR brain-fart going on*. I didn't notice the OP passing a 2D container into the function. (see my follow-up reply)

*at least I caught my screw-up, eventually. *ouch*

[lastchance]

Change auto to int and you'll be fine.

I'm more intrigued by the fact that you are mixing cout and printf.

[George P]

An array of vectors. Creating and passing a 2D vector might have been a better way to go, but what-the-hey. YMMV.

void printGraph(std::vector<std::vector<int>> adj)

One advantage to a 2D vector is it can be "ragged." Each row doesn't have to contain the same number of columnar elements:

#include <iostream>
#include <vector>

void print(std::vector<std::vector<int>>);

int main()
{
   std::vector<std::vector<int>> vec { { 1, 2, 3 }, { 2, 4, 6, 8 }, { 3, 6 } };

   print(vec);
}

void print(std::vector<std::vector<int>> v)
{
   for (int r { }; r < v.size(); r++)
   {
      for (const auto& c : v[r])
      {
         std::cout << c << ' ';
      }
      std::cout << '\n';
   }
}

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