Bubble sort 2D array in C

Question

I need a function to bubble sort this randomly generated 2D array. Also with rand() method I wanted it to generate numbers between (1, 1000000) but it doesnt give the required range, any suggestion to find out a solution?

int **matrix()
{

    int **matrix;
    int row, column;
    long s, k;
    int i,j,f,swap;


    srand(time(NULL));
    printf("Number of rows: ");
    scanf("%d", &row);

    printf("Number of column: ");
    scanf("%d", &column);


    matrix = (int **) calloc(row, sizeof(int));


    for(i = 0; i < row; i++)
        matrix[i] = (int *) calloc(column, sizeof(int));


    for(s = 0; s < row; s++)
    {
        for(k = 0; k < column; k++)
        {

            matrix[s][k]=rand()%10000000;
        }
    }

    for(s = 0; s < row; s++)
    {
        for(k = 0; k < column; k++)
            printf("%4d \t\t", matrix[s][k]);

        printf("\n");
    }


    for(i = 0; i < row; i++)
        free((void *) matrix[i]);


    free((void *) matrix);

    return **matrix;

}

`matrix = (int **) calloc(row, sizeof(int));` --> `matrix = calloc(row, sizeof(int *));` OT: I will use `column` instead of `colon` — David Ranieri, May 26 '20 at 12:55
Try printing [`RAND_MAX`](https://en.cppreference.com/w/cpp/numeric/random/RAND_MAX). It may be less than 10000000. — Fred Larson, May 26 '20 at 12:57
The memory allocation method used here is slightly flawed, (see answer) _and_ will not create contiguous memory, which may complicate how the bubble sort is done. Have you considered using [VLA](https://stackoverflow.com/questions/22530363/whats-the-point-of-vla-anyway)? That would produce a contiguous block of memory. For example: `int rows = 1000; int cols = 1000; int array[rows][cols] = {0};` creates `1000000` sequential and contiguous `int` memory locations, which can then be bubble sorted in the usual way: In a nested `i — ryyker, May 26 '20 at 14:57
Does this answer your question? [BubbleSorting C language](https://stackoverflow.com/questions/42043489/bubblesorting-c-language) — mozboz, May 26 '20 at 22:16

ryyker · Accepted Answer · 2020-05-26T14:39:56.120

Sorting a 2D array with bubble sort is a little different that sorting a single dimensional array. This example may help with that part of your question.

Other issues:

Based on this section:

for(i = 0; i < row; i++)
     matrix[i] = (int *) calloc(column, sizeof(int));

The line in the preceding section:

 matrix = (int **) calloc(row, sizeof(int));
                                        ^

Should be allocating memory for int *

 matrix = calloc(row, sizeof(int *));
                                 ^

(Note the cast for calloc() has also been removed. In C casting the return of [c][m][re]alloc is not recommended.)

Also with rand() method I wanted it to generate numbers between (1, 1000000) but it doesnt give the required range, any suggestion to find out a solution?

( With credit to this answer )

rand() expanded to provide a pseudo random distribution of 1000000 unique values:

unsigned long rand_ex(void);

int main(void){

    srand(clock());
    for(int  i=0;i<100;i++)
    {
        printf("%10d:  %10lu\n", i, rand_ex());
    }
    return 0;
}

unsigned long rand_ex(void)
{     
    unsigned long x;
    x = rand();
    x <<= 15;
    x ^= rand();
    x %= 1000001;

    return x;
}

Bubble sort 2D array in C

1 Answers1