how to init 2d array ?

This is a discussion on how to init 2d array ? within the C# Programming forums, part of the General Programming Boards category; hi all~ i'm new to C# and get confused this moment with 2d array initialization. i declared 2d array like ...

  1. #1
    flashing vampire black's Avatar
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    how to init 2d array ?

    hi all~

    i'm new to C# and get confused this moment with 2d array initialization. i declared 2d array like this:
    Code:
    int[,] = new int[2, 1];
    and how to initialize them with the same line ?
    Never end on learning~

  2. #2
    the hat of redundancy hat nvoigt's Avatar
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    If you need to do so, you can initialize n-dimensional arrays like this:

    PHP Code:
    int[,] array = new int[2,3] {{1,2,3},{5,6,7}}; 
    hth
    -nv

    She was so Blonde, she spent 20 minutes looking at the orange juice can because it said "Concentrate."

    When in doubt, read the FAQ.
    Then ask a smart question.

  3. #3
    flashing vampire black's Avatar
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    Quote Originally Posted by nvoigt
    If you need to do so, you can initialize n-dimensional arrays like this:

    PHP Code:
    int[,] array = new int[2,3] {{1,2,3},{5,6,7}}; 

    thanx but i tried it and it didnt work ???
    Never end on learning~

  4. #4
    l'Anziano DavidP's Avatar
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    it should work. if it does not, then something else is wrong with your program.

    here is a quick little program using that same code that nv posted:

    Code:
    using System;
    
    class myprog
    {
    	static void Main ( string [] args )
    	{
    		int[,] array = new int[2,3] {{1,2,3},{5,6,7}};
    
    		for ( int k = 0; k < 2; k++ )
    			for ( int j = 0; j < 3; j++ )
    				Console.WriteLine ( array[k,j] );
    	}
    }
    My Website

    "Circular logic is good because it is."

  5. #5
    flashing vampire black's Avatar
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    ok i succeed in establishing the 2d array but failed when output it ??? here is my code(an .aspx file):
    Code:
    <%
    	int[,] arr = new int[2, 3] {{1, 2, 3}, {4, 5, 6}};
    	Response.Write(arr[0][0]);
    %>
    the compiler hint the error happened at the line which i Response.Write the result, what's wrong there ???
    Never end on learning~

  6. #6
    the hat of redundancy hat nvoigt's Avatar
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    So what kind of error is it ? Can you post the exact error message please ?
    If it's a runtime error, can you catch the exception and output the stack trace and error message please ?
    ( Both are properties of the exception object )

    Edit:
    Also, make sure you don't mix jagged and rectangular arrays.

    array[][] is not the same as array[,]
    hth
    -nv

    She was so Blonde, she spent 20 minutes looking at the orange juice can because it said "Concentrate."

    When in doubt, read the FAQ.
    Then ask a smart question.

  7. #7
    flashing vampire black's Avatar
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    Quote Originally Posted by black
    ok i succeed in establishing the 2d array but failed when output it ??? here is my code(an .aspx file):
    Code:
    <%
    	int[,] arr = new int[2, 3] {{1, 2, 3}, {4, 5, 6}};
    	Response.Write(arr[0][0]);
    %>
    the compiler hint the error happened at the line which i Response.Write the result, what's wrong there ???
    to my surprise i found this would work:
    Code:
    Response.Write(arr[0, 0]);
    cant we get value with the format like arr[0][0] any more ???
    Never end on learning~

  8. #8
    the hat of redundancy hat nvoigt's Avatar
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    I see, you found it while I was editing my post

    int [,] is a rectangular array, that is an array that has n dimensions.

    int[][] is a jagged array, that is an array of arrays.
    hth
    -nv

    She was so Blonde, she spent 20 minutes looking at the orange juice can because it said "Concentrate."

    When in doubt, read the FAQ.
    Then ask a smart question.

  9. #9
    flashing vampire black's Avatar
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    Quote Originally Posted by nvoigt
    I see, you found it while I was editing my post

    int [,] is a rectangular array, that is an array that has n dimensions.

    int[][] is a jagged array, that is an array of arrays.
    thanx but... what's the difference between them ? i remembered C++ and C also index multi dimention array value with something like arr[1][2][3], really confused...
    Never end on learning~

  10. #10
    the hat of redundancy hat nvoigt's Avatar
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    In a rectangular array, each column and row has to have the same size like this: ( array[4,7] )

    0123456
    0123456
    0123456
    0123456

    while a jagged array is an array of arrays, where you have two different dimensions and as such you can put another array length into each line: ( array[4][] )

    0123456789
    01234
    01234567
    0123456
    hth
    -nv

    She was so Blonde, she spent 20 minutes looking at the orange juice can because it said "Concentrate."

    When in doubt, read the FAQ.
    Then ask a smart question.

  11. #11
    flashing vampire black's Avatar
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    thanx nvoigt, and i read the part for jagged arraay from C# primer, which has the same remarks

    but i'd really used to deal with multi arrays like this arr[1][2], can rectangle array apply this way or is there any substitute for arr[1, 2] ?
    Never end on learning~

  12. #12
    the hat of redundancy hat nvoigt's Avatar
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    Well, if you do some initialization work yourself and take a slight performance loss into account ( no biggie with a garbage collected language anyway ) you can build your 2d aray as a jagged array of same size arrays and use the [][] notation anyway, but it's confusing for readers and a lot of extra work just to avoid the comma
    hth
    -nv

    She was so Blonde, she spent 20 minutes looking at the orange juice can because it said "Concentrate."

    When in doubt, read the FAQ.
    Then ask a smart question.

  13. #13
    flashing vampire black's Avatar
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    Quote Originally Posted by nvoigt
    Well, if you do some initialization work yourself and take a slight performance loss into account ( no biggie with a garbage collected language anyway ) you can build your 2d aray as a jagged array of same size arrays and use the [][] notation anyway, but it's confusing for readers and a lot of extra work just to avoid the comma
    thanx nvoigt i think i would learn this new feature to make performance better
    Never end on learning~

  14. #14
    /*enjoy*/
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    salut je ne parle pas l'anglai mais tupeux traduire cette page
    bon en ce qui concerne l' init du 2d
    voila comment tu peux proceder
    /*1er*/
    int t[variablename][variablename];/*matrice */
    ou
    int t[?1][?2]={les valeur pour ?1 seperer d'une vergile }{les valeur de ?2 separer d'une vergule}
    je croit bien que tu a comprit
    si ce n'ai pas le cas tu peux m'expliquer ton problem exact et je peux t'offrir de laide
    mon e-mail est :ziro@voila.fr

  15. #15
    the hat of redundancy hat nvoigt's Avatar
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    Sorry, I don't speak french. Maybe you could rephrase your question in english ( or german so I can translate ) ?
    hth
    -nv

    She was so Blonde, she spent 20 minutes looking at the orange juice can because it said "Concentrate."

    When in doubt, read the FAQ.
    Then ask a smart question.

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