Function passing of multidimensional array in c -

#include <stdio.h>  void spiral(int a[10][10]) {     printf("%d", a[1][3]); }  int main() {     int r, c, j, i;     scanf("%d%d", &r, &c);     int a[r][c];     (i = 0; < r; i++)         (j = 0; j < c; j++) {             scanf("%d", &a[i][j]);         }      spiral(a);     return 0; } 

when give 3 x 6 array

 1   2   3   4   5   6  7   8   9  10  11  12 13  14  15  16  17  18 

the output 14, while should 10

how fix issue?

if enter 3 , 6 r , c (respectively) type of a not int[10][10] (or int(*)[10] spiral argument is), it's int[3][6]. memory layout different arrays, leading undefined behavior.

you can solve passing size along function, , using in declaration of array:

void spiral(const size_t r, const size_t c, int (*a)[c]) { ... } 

call expected:

spiral(r, c, a); 

---

as noted using int a[r][c] argument might easier read , understand, gives false impression a array. it's not. compiler treats argument pointer array of c integers, i.e. int (*a)[c].

this makes me little conflicted... on 1 hand i'm making things easier read , understand (which means easier maintain), on other hand newbies wrong , think 1 can pass array intact when in fact decays pointer can lead misunderstandings.