int a[5] = {1,2,3,4,5};
int b[3][4] = {1,2,3,4,5,6,5,1,2,4,5,6};
  
printf("%d\n",sizeof(a));   // 20
printf("%d\n",sizeof(b));   //48
printf("%d\n",sizeof(b[0]));    //16
printf("%d\n",sizeof(b[0][1])); //4

指针的使用场景

指针的作用：传递与偏移