Multy Dim Array

anish kn

I need a multi dimensional (Jaged Array) for entering Matrix data. Can any body telll whats wrojng with the code I have attched here...

a=new int[m][];
      for(i=0;i      {

Console.WriteLine("No. Of Cols: in Raw "+(i+1));
      n=Convert.ToInt32(Console.ReadLine());

for (j=0;j         {
  Console.WriteLine("Enter cl: "+(j+1));
        a[i][j]=Convert.ToInt32(Console.ReadLine());
         }
      }

      for( i=0;i      {
for ( j=0;j         {
         Console.Write(a[i][j]+"\t");
         }
Console.WriteLine("\n");
      }

}
}

Error Message while executing the progrma:"Unhandled Exception: System.NullReferenceException: Object reference not set to
an instance of an object.
at MyArrayc2.Main()"

2 Replies

Know the answer? Post it — somebody with the same question will find it here.

anish kn19y ago
Thank you very much... now everithing works well
Alan19y ago
The problem is that you've forgotten to initialize the 'm' arrays in the jagged array. Change the first bit of code to this and all should be well:

a = new int[m][];
for(i=0;i {
    Console.WriteLine("No. Of Cols: in Raw "+(i+1));
    n=Convert.ToInt32(Console.ReadLine());
    a[i] = new int[n]; // added this line

    for (j=0;j    {
        Console.WriteLine("Enter cl: "+(j+1));
         a[i][j]=Convert.ToInt32(Console.ReadLine());
    }
}