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c#multidimensional-arrayjagged-arrays
Garbez François
Garbez François

Reputation: 357

Jagged array of multidimensionnal array int types

I'm now learning C# and making a couple of challenges, i managed to pass easily most of them but sometimes there are things i don't understand (i'm a python dev basically)...

Create a function that takes an integer and outputs an n x n square solely consisting of the integer n.

E.G : SquarePatch(3) ➞ [
  [3, 3, 3],
  [3, 3, 3],
  [3, 3, 3]
]

So i went trough docs about multidimentionnal arrays, jagged arrays.But i get an error (kind of errors i get the most while learning c#, i never had that kind of problems in python. It's about TYPES convertion !) I mean i often have problems of types.

So here's my code :

public class Challenge 
    {
        public static int[,] SquarePatch(int n) 
        {
        int[ ][,] jaggedArray = new int[n][,];
        for (int i=0;i<n;i++)
        {
            for(int j=0;j<n;j++)
            {
                for(int k=0;k<n;k++)
                    {
                        return jaggedArray[i][j, k]=n;
                    }
            }
        }
        }
}

What is actually very boring is that in that kind of challenges i don't know how to make equivalent to python "print tests" ! So i don't even know what's going on till the end...

And i get this error :

Cannot implicitly convert type int to int[,]

Upvotes: 0

Views: 187

Answers (2)

Dmitrii Bychenko
Dmitrii Bychenko

Reputation: 186833

Well, you should return 2d array: int[,]:

public static int[,] SquarePatch(int n) {
  // Do not forget to validate input values (n) in public methods
  if (n < 0)
    throw new ArgumentOutOfRange(nameof(n));

  // We want to return 2d array, here it is
  int[,] result = new int[n, n];
  
  // All we should do now is to loop over 2d array and fill it with items
  for (int r = 0; r < result.GetLength(0); ++r)
    for (int c = 0; c < result.GetLength(1); ++c)
      result[r, c] = n;

  return result;
}

You can change your challenge and return jagged array int[][] (array of arrays):

public static int[][] SquarePatch(int n) {
  // Do not forget to validate input values (n) in public methods
  if (n < 0)
    throw new ArgumentOutOfRange(nameof(n));

  // now we want to return array of size n (lines) of arrays:  
  int[][] result = new int[n][];
  
  // We loop over lines
  for (int r = 0; r < result.Length; ++r) {
    // We create line after line
    int[] line = new int[n];
    // assign each line to result
    result[r] = line;

    // and fill each line with required items
    for (int c = 0; c < line.Length; ++c)
      line[c] = n;
  }

  return result;
}

Upvotes: 1

Cetin Basoz
Cetin Basoz

Reputation: 23867

n as in the error message, cannot be converted to int[,]. It is an int. You don't need a jagged array but simply an array of n by n, hence arr[n,n].

public static int[,] SquarePatch(int n, int v)
{
    int[,] myArray = new int[n,n];
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < n; j++)
        {
            myArray[i,j] = v;
        }
    }
    return myArray;
}

Here n is the size for row and cols and v is the value to initialize all members to.

Upvotes: 1

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