无法理解数组的行为

I have the following code :

我有以下代码:

 #include<stdio.h>
   void func(int [][3]);

   int main(){
           int a[][3] = {{1,2,3}, {4,5,6}, {7,8,9}};
           func(a);
           printf("%d", a[2][1]);
   }       

  void func(int b[][3]){
          ++b;
          b[1][1] = 17;
  }
 #incl