Arduino - 在setup（）中声明的变量不在函数范围内

Question

我计划编写一个修改二维数组的函数，以便每个坐标都设置为0.在setup()我声明了displayWidth和displayHeight但是可以＆＃39;在generateBoard()函数中访问它们，因为它们不在同一范围内。

代码：

void generateBoard(int board[][]) {
  // Modifies the array board by setting zeros

  for (int y=0; y < displayHeight; y++) {
    for (int x=0; x < displayWidth; x++) {
      board[x][y] = 0;
    }
  }
}

void setup() {
  int displayWidth  = 14;
  int displayHeight = 10;

  int board[displayWidth][displayHeight];
  generateBoard(board); 
}

void loop() {}

设置（）

中的本地范围异常

error: declaration of 'board' as multidimensional array must have bounds for all dimensions except the first
error: declaration of 'board' as multidimensional array must have bounds for all dimensions except the first
In function 'void generateBoard(...)':
error: 'displayHheight' was not declared in this scope
error: 'displayWidth' was not declared in this scope
error: 'board' was not declared in this scope

---

固定版和工作版：

const int displayWidth  = 14;
const int displayHeight = 10;
int board[displayWidth][displayHeight];

void generateBoard() {
  // Modifies the array board by setting zeros

  for (int y=0; y < displayHeight; y++) {
    for (int x=0; x < displayWidth; x++) {
      board[x][y] = 0;
    }
  }
}

void setup() {
  generateBoard(); 
}

void loop(){}

Answer 1

全局声明board，displayWidth和displayHeight（在任何函数定义之外）。像这样：

 const int displayWidth  = 14;
 const int displayHeight = 10;
 int board[displayWidth][displayHeight];

void generateBoard() {
  // Modifies the array board by setting 0

  for (int y=0; y < displayHeight; y++) {
    for (int x=0; x < displayWidth; x++) {
      board[x][y] = 0;
    }
  }
}

void setup() {
  generateBoard(); 
}

void loop() {}

在setup（）中声明它们使它们成为局部变量 - 局部变量只能被声明它们的函数访问。