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Java Forum / General / March 2007Appending to arrays/array help
Hi, I have a data structure as follows: fig. 1: int[] array = {15829289595299, 23848108482942, 2842948284422, ...}; The numbers in the array might be 750 digits long. Firstly, is this the best method of storing the numbers? or should I do an array of arrays so each number has an array of chars? Next, assuming the array in fig. 1, how would I append extra digits to each array item? I dont want to += add a new digit to the total value, but add it on the end. Thanks in advance! Sorry should mention, the array is of predetermined size, i.e. : public int[] foo(int s) { c = new int[s]; for(int i=0; i<s; i++) { for(int n: somearray) { c[i] = random.nextInt(); } } return c; } c[] being the array in question. Thanks > Hi, I have a data structure as follows: > > fig. 1: int[] array = {15829289595299, 23848108482942, > 2842948284422, ...}; This will not work, because the numbers are bigger than Integer.MAX_VALUE. Have you looked at java.math.BigInteger? Patricia > > Hi, I have a data structure as follows: > [quoted text clipped - 6 lines] > > Patricia I thought this might be the case. I think I might be better storing the numbers in a string. I can then access each digit and use .append to add digits right? >>> Hi, I have a data structure as follows: >>> fig. 1: int[] array = {15829289595299, 23848108482942, [quoted text clipped - 8 lines] > I think I might be better storing the numbers in a string. I can then > access each digit and use .append to add digits right? If you go with a string-like solution and need to append often, consider StringBuilder. Do you need to do arithmetic on these things? That might make the difference between BigInteger and StringBuilder. Patricia > >>> Hi, I have a data structure as follows: > >>> fig. 1: int[] array = {15829289595299, 23848108482942, [quoted text clipped - 14 lines] > > Patricia No arithmetic required as such. I just need to extract digits at certain positions in the array. Could i do this like: array[i][300] to get the 299th digit of i'th array? Thanks >>>>> Hi, I have a data structure as follows: >>>>> fig. 1: int[] array = {15829289595299, 23848108482942, [quoted text clipped - 17 lines] > > Thanks Do you know the max length for a given number in advance? If so, consider byte[][] array, and you would access array[i][300]. If you don't know a reasonably accurate maximum length, consider using an array of StringBuilder. It will handle extending the array for you. Patricia JamesG wrote: >> No arithmetic required as such. I just need to extract digits at >> certain positions in the array. >> Could i do this like: array[i][300] to get the 299th digit of i'th >> array? > Do you know the max length for a given number in advance? If so, > consider byte[][] array, and you would access array[i][300]. > > If you don't know a reasonably accurate maximum length, consider using > an array of StringBuilder. It will handle extending the array for you. Or even List<StringBuilder>. Then you can have an arbitrarily large list of arbitrarily large CharSequences of varying lengths. To the OP: Have you looked at the API docs for StringBuilder since Patricia suggested the class? BigInteger? After those, look at List and its implementations. If you don't research the suggestions how will you know if they'll help? -- Lew > JamesG wrote: >>> No arithmetic required as such. I just need to extract digits at [quoted text clipped - 19 lines] > > After those, look at List and its implementations. I'd even consider an ArrayList of ArrayList of Byte, with just 10 distinct Byte objects, one for each value. It would cost a 32 or 64 bit reference for each element, less space efficient than StringBuilder. > If you don't research the suggestions how will you know if they'll help? Especially important because I don't think we have been given enough size and operation frequency data to actually pick a really good structure. All we can do is suggest structures to consider. Patricia Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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