shuffle 2-dimensional array

This is a discussion on shuffle 2-dimensional array within the C Programming forums, part of the General Programming Boards category; Hi, I found this code for shuffle one-dimensional int array somewhere: Code: void shuffle(int *array, size_t n) { if (n ...

  1. #1
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    shuffle 2-dimensional array

    Hi,

    I found this code for shuffle one-dimensional int array somewhere:

    Code:
    void shuffle(int *array, size_t n)
    {
        if (n > 1) {
            size_t i;
    	for (i = 0; i < n - 1; i++) {
    	  size_t j = i + rand() / (RAND_MAX / (n - i) + 1);
    	  int t = array[j];
    	  array[j] = array[i];
    	  array[i] = t;
    	}
        }
    }
    How can I make change to this function to shuffle 2-dimensional array. This is the declaration of the 2-dimensional array I need to shuffle.

    Code:
    char list[2000][20];
    This array is an array of string (20 char max). I need to shuffle the outer array not the inner one.

    Any help would be really appreciated,
    Pat

  2. #2
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    So have a temporary 20 char string and use strcpy to the swap.

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  3. #3
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    3rd forum I've seen this on - spamalot?
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    What do you mean when you say need to shuffle the outer array not the inner one.

  5. #5
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    Quote Originally Posted by itCbitC View Post
    What do you mean when you say need to shuffle the outer array not the inner one.
    From this:
    Code:
    char arr[3][10] = { "Hello", "New", "World" };
    
    shuffle(arr);
    we want something like "New", "World", "Hello" in the array, not "eNl", "Hwldo" ,"Wrdll" [I'm not sure that's actually not lost or gained some letters, but I think it gets the message across].

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    Well thanks for the great explanation matsp, I thought it is the exact opposite where the columns of each row are shuffled around.

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