int arr2d1[2][3] ={0,1,2,3,4,5};
2行3列

// 第二维不能省略
// int arr[][]  error: array has incomplete element type 'int []'
void printArr2D(int arr[][3],int rows,int columns){
  for(int i=0;i < rows;i++){
    for(int j=0;j < columns;j++){
      printf("%d ",arr[i][j]);
    }
    printf("\n");
  }
  printf("\n");
}



#include "stdio.h"

void printArr(int arr[],int size){
  for(int i=0;i < size;i++){
    printf("%d ",arr[i]);
  }
  printf("\n");
}

// 第二维不能省略
// int arr[][]  error: array has incomplete element type 'int []'
void printArr2D(int arr[][3],int rows,int columns){
  for(int i=0;i < rows;i++){
    for(int j=0;j < columns;j++){
      printf("%d ",arr[i][j]);
    }
    printf("\n");
  }
  printf("\n");
}
int main(){
  int arr1[] ={0,1,2};
  int arr2[2] ={0};
  int arr3[2] ={};
  
  
  printArr(arr1,3);
  printArr(arr2,2);
  printArr(arr3,2);
  
  printf("\n");
  //
  int arr2d1[2][3] ={0,1,2,3,4,5};
  printArr2D(arr2d1,2,3);
  
  int arr2d2[2][3] ={0,1,2,3,};
  printArr2D(arr2d2,2,3);
  
  int arr2d3[2][3] ={{0},{1,2}};
  printArr2D(arr2d3,2,3);
  
  return 0;
}