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Wanted some help about arrays
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swapnil deo
Greenhorn
Joined: May 30, 2007
Posts: 6
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WELL IM JUST A BEGENINER FOR JAVA...AND IM GETTING SOME PROBLEMS WHILE INITIALIZING A MULTI DIMENSIONAL ARRAY..!!! ACTUALL WHAT I WANTED TO DO IS..DECLARE A MULTI DIMENSIONAL ARRAY...AND WANT TO ENTER THE ELEMENTS IN RUNTIME....I.E. I WANT THE VALUES TO BE ENTERD BY THE USER... IF ANY1 CAN PLZZ HELP ME OUT WID SOLVING DIS PROBLEM... WAITING FOR YOUR REPLIES PEOPLE...PLZZ HELP ME EDIT by mw: Removed shouting from subject line. [ May 30, 2007: Message edited by: marc weber ]
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Campbell Ritchie
Sheriff
Joined: Oct 13, 2005
Posts: 32839
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Welcome to the Ranch. Please don't use upper-case throughout and please don't use abbreviations like ANY1. Have you been through the Java Tutorial about arrays? You realise there is, strictly speaking, no such thing as a multi-dimensional array in Java, only arrays of arrays. The examples in the link I gave you tell you how to set up arrays; you would have to ask how many entries there are going to be. Example: "Mr Campbell Ritchie" can be divided into a 3-member String[] using the split() method of the String class and " " as its regular expression. Similarly "Swapnil Deo" can be divided into a 2-member String[]. You can use the length parameter of that array to set up a new array, and copy all the members in. Or even easier, set up a String[][] array, and copy your arrays into its members.
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Kaydell Leavitt
Ranch Hand
Joined: Nov 18, 2006
Posts: 682
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Welcome swapnil, If you have a "one-dimensional" array, the natural control structure to implement elements is one loop. If you have a "two-dimensional" array (really an array of arrays), the natural control stucture to initialize elements is a doubly-nested loop. etc. In addition to arrays (which are part of the Java language), see also the classs: ArrayList etc. Kaydell
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Stan James
(instanceof Sidekick)
Ranch Hand
Joined: Jan 29, 2003
Posts: 8791
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Can you show us some code to see how far you've gotten and where you are stuck? If the whole thigns sounds overwhelming, maybe just do a one-dimensional array and see if you're getting values from the user and putting them into the array ok.
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A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi
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Kaydell Leavitt
Ranch Hand
Joined: Nov 18, 2006
Posts: 682
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One clue is that in Java, array indexes start with a zero index and go to length minus one. Kaydell
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swapnil deo
Greenhorn
Joined: May 30, 2007
Posts: 6
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thanks everyone for your replies...but still im not clear with this concept of "array of arrays" Campbell Ritchie : i went through the link which you gave and read things about array but the program over there was as follows : class ArrayDemo { public static void main(String[] args) { int[] anArray; // declares an array of integers anArray = new int[10]; // allocates memory for 10 integers anArray[0] = 100; // initialize first element anArray[1] = 200; // initialize second element anArray[2] = 300; // etc. anArray[3] = 400; anArray[4] = 500; anArray[5] = 600; anArray[6] = 700; anArray[7] = 800; anArray[8] = 900; anArray[9] = 1000; System.out.println("Element at index 0: " + anArray[0]); System.out.println("Element at index 1: " + anArray[1]); System.out.println("Element at index 2: " + anArray[2]); System.out.println("Element at index 3: " + anArray[3]); System.out.println("Element at index 4: " + anArray[4]); System.out.println("Element at index 5: " + anArray[5]); System.out.println("Element at index 6: " + anArray[6]); System.out.println("Element at index 7: " + anArray[7]); System.out.println("Element at index 8: " + anArray[8]); System.out.println("Element at index 9: " + anArray[9]); } } The output from this program is: Element at index 0: 100 Element at index 1: 200 Element at index 2: 300 Element at index 3: 400 Element at index 4: 500 Element at index 5: 600 Element at index 6: 700 Element at index 7: 800 Element at index 8: 900 Element at index 9: 1000 im pretty clear with the above code now in the above code we are initializing the array at the very begening..ie in the code itself..but my doubt was how do we insert values in runtime like in the following C++ code : int a[][]; int x; cout<< "enter dim of array"; cin>> x; cout << "enter array elements"; for(int i=0;i<x;i++)//this for loop will ask user to enter values at runtime { for (int j=0;j<x;j++) { cin>>a[i][j]; //user will enter values when this line gets executed } } for(int i=0;i<x;i++)//this for loop will print the output { for (int j=0;j<x;j++) { cout<<"print"; cout<<a[i][j]; } } o/p: enter dim of array: 3 3 enter array elements: 1 2 3 4 5 6 print: 1 2 3 4 5 6 now in this way...how do i get to enter values to 2-dimensional arrays in java..??? this is my real doubt...??? thanks for your time..!!
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Kaydell Leavitt
Ranch Hand
Joined: Nov 18, 2006
Posts: 682
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Note that cin and cout are C++ streams. In Java the standard streams are: System.in for standard input System.out for standard output and System.err for error output. I found something useful at the following website: Example of using System.in The above example shows you how to read from the standard input and write to the standard output, but leaves you some work so that you can learn by writing your own code. One more hint is that to create an array, you can use the following syntax: int[][] intArray = new int[5][6]; The line of code above will create a 5 by 6 array of int. The array sizes don't have to be known at compile-time, so you can read the array sizes from the console and use x & y for the array sizes. Kaydell [ June 03, 2007: Message edited by: Kaydell Leavitt ]
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subject: Wanted some help about arrays
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