c - 初始化可变长度数组

Question

在初始化可变长度数组时，编译器会给出错误消息：

[Error] variable-sized object may not be initialized  

代码片段：

int n; 
printf("Enter size of magic square: ");
scanf("%d",&n);

int board[n][n] = {0};

可变长度数组应该如何初始化？以及为什么它的所有元素都没有0按照下面给出的方式初始化；

   int board[n][n];
   board[n][n] = {0};

?

Answer 1

你必须使用memset：

memset(board, 0, sizeof board);

Answer 2

VLAs cannot be initialized by any form of initialization syntax. You have to assign the initial values to your array elements after the declaration in whichever way you prefer.

C11: 6.7.9 Initialization (p2 and p3):

No initializer shall attempt to provide a value for an object not contained within the entity being initialized.

The type of the entity to be initialized shall be an array of unknown size or a complete object type that is not a variable length array type.

Answer 3

1.您可以简单地初始化数组如下 -

int n; 
printf("Enter size of magic square: ");
scanf("%d",&n);

int board[n][n];
for(int i=0; i<n; i++)
   for(int j=0; j<n; j++)
   {
      board[i][j] = 0;
   }
}

2. memset()应该只在你想将数组设置为“0”时使用。