Splitting a 2D array to an array of smaller 2D arrays in C -

given:

1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8  1 2 3 4 5 6 7 8 

i want split 2d array (struct matrix) array of struct matrix given chunksize cs: assume cs 2, answer be

seg[0]: 1 2  1 2  1 2 seg[1]: 3 4  3 4  3 4 .... seg[3]: 7 8 7 8 7 8 

here matrix struct:

typedef struct matrix {     int nrow;     int ncol;     int **element; } matrix; 

and here function seperates them:

void segmentmatrix(matrix input,matrix* segs,int chunksize, int p) {     int i,j,r;      //allocate segs     (i = 0; i<p;i++)     {         creatematrix(&(segs[i]),input.nrow ,chunksize,0);     }      //now copy elements input segs     //where seg0 takes 0 cs cols of a, , rows, , seg1 takes cs 2cs ...     printf("stats:\n\t p: %d\t cs: %d\n",p,chunksize);     (r = 0; r<p; r++) {         (i = 0; i<input.nrow;i++) {             (j = r*chunksize; j<r*chunksize+chunksize-1; j++) {                  //i tried (&(segs[r]))->element... doesn't work, produces wrong data                  segs[r].element[i][j] = input.element[i][j];          }     }     printm(segs[r]);     }   } 

note printm prints matrix, knows limits checking segs[r].nrow , ncol , creatematrix takes following inputs (&matrix, number of rows, number of colums, filltype) , mallocs within.

filltype:  0- generates zeroth matrix 1- generates identity else a[i][j] = j; simplicity 

the problem if print matrices segs[i], come down default value given creatematrix, , not newly added values.

clarification: okay, if guys check last printm in segmentmatrix function, outputs matrices if loops didn't happen, aka, can delete loops , same output.. did wrong in line (taken segmentmatrix)

segs[r].element[i][j] = input.element[i][j]; 

i don't see why , manipulating multiplication chunksize , r (which uninitialized anyway), i'd suggest simplifying code (rule of thumb: if seems messy, it's complex). need 3-dimensional array store array of chunks, , modulo arithmetic plus integer division insert appropriate column of appropriate chunk:

/* variable-sized dimension of `chunks' argument w / chsz elements big  * (it's number of chunks)  */ void split(int h, int w, int mat[h][w], int chsz, int chunks[][h][chsz]) {     /* go through each row */     (int = 0; < h; i++) {         /* , in each row, go through each column */         (int j = 0; j < w; j++) {             /* , each column, find chunk goes in              * (that's j / chsz), , put proper row              * (which j % chsz)              */             chunks[j / chsz][i][j % chsz] = mat[i][j];         }     } } 

demonstration, a. k. a. how call it:

int main(int agrc, char *argv[]) {     const size_t w = 8;     const size_t h = 3;     const size_t c = 2;      int mat[h][w] = {         { 1, 2, 3, 4, 5, 6, 7, 8 },         { 1, 2, 3, 4, 5, 6, 7, 8 },         { 1, 2, 3, 4, 5, 6, 7, 8 }     };      int chunks[w / c][h][c];      split(h, w, mat, c, chunks);      (int = 0; < w / c; i++) {         (int j = 0; j < h; j++) {             (int k = 0; k < c; k++) {                 printf("%3d ", chunks[i][j][k]);             }             printf("\n");         }         printf("\n\n");     }      return 0; }