arrays

[ushma agarwal]

somebody please tell me why //line 2 is giving compiler error?

class M {
  public static void main(String[] args) {
    int[] a1[],a2[];  // 1
    int []a3,[]a4;    // 2
    int []a5,a6[];    // 3
    int[] a7,a8[];    // 4
}
}

[Deepak Jain]

You cannot have a []before the variable if you are declaring an array using comma as in all the cases above.

public class Test {
public static void main(String[] args) {    
int[] a1[],[]a2[];  // 1
int []a3,[]a4;    // 2
int []a5,[]a6[];    // 3
int[] a7,[]a8;    // 4

  }
}

Compiler errors for a2, a4, a6 and a8.
So your program can be corrected as below

public class Test {
public static void main(String[] args) {    
int[] a1[],a2[];  // 1
int []a3,a4[];    // 2
int []a5,a6[];    // 3
int[] a7,a8;    // 4

  }
}

Also you might be surpirsed to know that
a1 is double dimention array of primitive ints
a2 is double dimention array of primitive ints
a3 is single dimention array of primitive ints
a4 is double dimention array of primitive ints
a5 is single dimention array of primitive ints
a6 is double dimention array of primitive ints
a7 is single dimention array of primitive ints
a8 is single dimention array of primitive ints
Thanks
Deepak

[ushma agarwal]

thanks deepak
now i got the point.

[Arvind Mahendra]

Originally posted by Deepak Jain:

[/CODE]
Also you might be surpirsed to know that
a1 is double dimention array of primitive ints
a2 is double dimention array of primitive ints
a3 is single dimention array of primitive ints
a4 is double dimention array of primitive ints
a5 is single dimention array of primitive ints
a6 is double dimention array of primitive ints
a7 is single dimention array of primitive ints
a8 is single dimention array of primitive ints
Thanks
Deepak

How so? How is a2,a4,a6 double dimension array of ints?

[Deepak Jain]

int[] a1[],a2[]; // 1
int []a3,a4[]; // 2
int []a5,a6[]; // 3
int[] a7,a8; // 4
Here a2, a4 and a6 all have thier own dimention becuase they are declared as a2[],a4[] and a6[]. Now since they are declared with comma operator and because [] is placed after the datatype , Hence [] gets applied to a2, a4 and a6 and therefore makes them a 2-dimentional array.
If you have
int a1[], a2[]; then here a2 is a single dimentional array.
Hope this clears.
But if you have
int[] a1, a2[] then a1 is 1-D and a2 is 2-D.
Thanks
Deepak

[Kelvin Chenhao Lim]

To avoid confusion, you should never declare arrays with the square brackets after the variable name. This syntax was basically just a concession to C/C++ programmers; in Java, it's best to think of the square brackets as part of the type name, and always write them as such (i.e. immediately following the element type name, without any spaces).

[Arvind Mahendra]

Originally posted by Deepak Jain:
int[] a1[],a2[]; // 1
int []a3,a4[]; // 2
int []a5,a6[]; // 3
int[] a7,a8; // 4
Here a2, a4 and a6 all have thier own dimention becuase they are declared as a2[],a4[] and a6[]. Now since they are declared with comma operator and because [] is placed after the datatype , Hence [] gets applied to a2, a4 and a6 and therefore makes them a 2-dimentional array.
If you have
int a1[], a2[]; then here a2 is a single dimentional array.
Hope this clears.
But if you have
int[] a1, a2[] then a1 is 1-D and a2 is 2-D.
Thanks
Deepak

Hmm. This is where the confusion is. I can understand a2[] being a 2-D array. but not a4 and a6.
In the case of a2 we have:
int[] a1[],a2[]; // so with this i can see that a2 is a 2-d array

but with
int []a3,a4[]; // shouldn't this mean that a3 is a 1-d array and so is a4? as each array has its own []. a3 has it before and a4 has its after.

If I had declared the array as []a3,[]a4 //then a3,a4 would both be 1-d array yes?
but if I declare as []a3,a4[] then a4 becomes a 2-d aray???
[ November 30, 2007: Message edited by: Chunnard Singh II ]

[Kelvin Chenhao Lim]

Hi Chunnard,

Don't be fooled by the spacing. These two statements are exactly the same:

int[] a3,a4[];

and

int []a3,a4[];