Array Declaration doubts

[Vegad Arvind]

Hi,
Here some Array declaration doubts :

1. int x[][] = new int[][];
//err array dimension missing
2. int x[][] = new int[][4];
//invalid array dimension
3. int x[][] = new long[4][];
//invalid incompitable type
4. int x[][] = new int[4][];
//valid
Why 3 is invalid and 4 is valid
Can anybody explain
Thanks
Avi

[pragati]

hi Vegad,
No. 3 has to be invalid as you are trying to put long value into integer array.

[ASHISH KUMAR]

Hi Vegad,
3 is invalid because, u r trying to cast a long array into
int array. Arrays of primitive type can't be casted into
other types.
4 is valid because u r declaring an array of 4 rows. and
each row can have same no. of columns or variable columns
later.
here is an exam. for ques. 4==>
int [][]x = new int[4][];
for(int i=0; i<x.length; i++)>
{
x[i] = new int[i+1];
}
now x[0] has 1 elament
x[1] has 2 element
x[2] has 3 elament
x[3] has 4 element
I hope this will help u.
Ashish

[V Srinivasan]

Hi,
long has 64 bit and int has 32 bit. Always right side variable's type should be matched to the left side or it should be less than the left side variable's type. Here you are trying to assign a long two dimentional array into integer two dimentional array. It is not, because of incompatible type. And one more thing, Arrays cannot be resized. If you want to change the arrays size first you have to create a new (desired length of) array and pass your existing arrays into it and you can delete the old arrays. I don't know what Ashish trying to say. Please clarify me if I am wrong.
Thanks

[This message has been edited by V Srinivasan (edited February 19, 2001).]