CODEWITHSUNDEEP
c++arraysreverse
nidhisoni
nidhisoni

Reputation: 51

no matching function for call to ‘begin(int [n])’

I tried many things but still, it's giving an error: 

no matching function for call to ‘begin(int [n])’

What's the best approach?

#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

int main() 
{
    int n;
    cin >> n;
    int arr[n];
    for(int i = 0; i < n; i++){
        cin >> arr[i];
    }
    reverse(begin(arr), end(arr));
    for(int j = 0; j < n; j++){
        cout << arr[j] <<" ";
    }
    return 0;
}

Upvotes: 3

Views: 3039

Answers (1)

JeJo
JeJo

Reputation: 32847

error:no matching function for call to ‘begin(int [n])’

This is because of that you have used non-standard Variable Length Array, here:

cin >> n;
int arr[n] ;

Therefore, it's not possible to apply the standard algorithms like std::reverse to this kind of non-standard arrays.

if you change it normal array with a size, like:

const int n = 3;
int arr[n] ;

The code what you wrote is valid and will work. See here

However, now you can not input the size of the array.

Whats the best approach?

Use std::vector instead.

Now you also have the option for reverse printing without using std::reverse, but using std::vector::reverse_iterator.(If that's all you wanted)

For instance: See output here

#include <vector>
#include <iostream>
#include <algorithm>

int main() 
{
   int n;
   std::cin >> n;
   std::vector<int> arr(n);
   for(int& ele: arr) std::cin >> ele;
   //std::reverse(std::begin(arr), std::end(arr));
   //for(const int ele: arr) std::cout << ele << " ";
   //or simply
   std::for_each(arr.rbegin(), arr.rend(),[](const int ele){ std::cout << ele << " "; });
   return 0;
}

Upvotes: 4

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