c#对未赋值变量的使用
本文关键字：变量 赋值 | 更新日期: 2023-09-27 17:54:42
所以基本上我有一个TicTacToe游戏类和一个派生类只是为了练习使用继承。类有几个方法，所有应该工作得很好，但在主函数中，当我最终使派生类的三个对象，我得到三个错误"使用未分配的局部变量'boardOne'"使用未分配的局部变量'boardTwo'"answers"使用未分配的局部变量'boardThree'"。我不明白为什么会这样，它们是对象，不是变量。
public class TicTacToe
{
protected char[] boardCells = new char[9];
public int boardSpacesUsed;
public TicTacToe() //constructor
{
boardCells[0] = '1';
boardCells[1] = '2';
boardCells[2] = '3';
boardCells[3] = '4';
boardCells[4] = '5';
boardCells[5] = '6';
boardCells[6] = '7';
boardCells[7] = '8';
boardCells[8] = '9';
boardCells[9] = ''0';
int boardSpacesUsed = 0;
}
public void playerOneMove()
{
bool space = false;
char cell = ''0';
while (space == false)
{
Console.WriteLine("Please enter cell number you wish to mark: ");
cell = Convert.ToChar(Console.ReadLine());
switch (cell)
{
case '1':
if (boardCells[0] == 'X' || boardCells[0] == 'O')
{
Console.WriteLine("Illegal Move");
}
else
{
boardCells[0] = 'X';
space = true;
}
break;
case '2':
if (boardCells[1] == 'X' || boardCells[1] == 'O')
Console.WriteLine("Illegal Move");
else
{
boardCells[1] = 'X';
space = true;
}
break;
case '3':
if (boardCells[2] == 'X' || boardCells[2] == 'O')
Console.WriteLine("Illegal Move");
else
{
boardCells[2] = 'X';
space = true;
}
break;
case '4':
if (boardCells[3] == 'X' || boardCells[3] == 'O')
Console.WriteLine("Illegal Move");
else
{
boardCells[3] = 'X';
space = true;
}
break;
case '5':
if (boardCells[4] == 'X' || boardCells[4] == 'O')
Console.WriteLine("Illegal Move");
else
{
boardCells[4] = 'X';
space = true;
}
break;
case '6':
if (boardCells[5] == 'X' || boardCells[5] == 'O')
Console.WriteLine("Illegal Move");
else
{
boardCells[5] = 'X';
space = true;
}
break;
case '7':
if (boardCells[6] == 'X' || boardCells[6] == 'O')
Console.WriteLine("Illegal Move");
else
{
boardCells[6] = 'X';
space = true;
}
break;
case '8':
if (boardCells[7] == 'X' || boardCells[7] == 'O')
Console.WriteLine("Illegal Move");
else
{
boardCells[7] = 'X';
space = true;
}
break;
case '9':
if (boardCells[8] == 'X' || boardCells[8] == 'O')
Console.WriteLine("Illegal Move");
else
{
boardCells[8] = 'X';
space = true;
}
break;
default:
Console.WriteLine("Cell Does NOT Exist!");
break;
}// end of switch statement
}//end of while loop
boardSpacesUsed++;
}// end of playerOneMove();
public void CPUMove() //method marks cell for CPU
{
int iCell = 0;
bool space = false;
while (space == false)
{
Random rand = new Random();
iCell = rand.Next(1, 9);
switch (iCell) //switch statement to mark the cell
{
case 1:
if (boardCells[0] == 'X' || boardCells[0] == 'O')
{
space = false;
}
else
{
boardCells[0] = 'O';
space = true;
}
break;
case 2:
if (boardCells[1] == 'X' || boardCells[1] == 'O')
space = false;
else
{
boardCells[1] = 'O';
space = true;
}
break;
case 3:
if (boardCells[2] == 'X' || boardCells[2] == 'O')
space = false;
else
{
boardCells[2] = 'O';
space = true;
}
break;
case 4:
if (boardCells[3] == 'X' || boardCells[3] == 'O')
space = false;
else
{
boardCells[3] = 'O';
space = true;
}
break;
case 5:
if (boardCells[4] == 'X' || boardCells[4] == 'O')
space = false;
else
{
boardCells[4] = 'O';
space = true;
}
break;
case 6:
if (boardCells[5] == 'X' || boardCells[5] == 'O')
space = false;
else
{
boardCells[5] = 'O';
space = true;
}
break;
case 7:
if (boardCells[6] == 'X' || boardCells[6] == 'O')
space = false;
else
{
boardCells[6] = 'O';
space = true;
}
break;
case 8:
if (boardCells[7] == 'X' || boardCells[7] == 'O')
space = false;
else
{
boardCells[7] = 'O';
space = true;
}
break;
case 9:
if (boardCells[8] == 'X' || boardCells[8] == 'O')
space = false;
else
{
boardCells[8] = 'O';
space = true;
}
break;
}
}
boardSpacesUsed++;
}
public void getBoardCells()
{
Console.WriteLine(" " + " " + " | " + " " + " | " + " ");
Console.WriteLine(" " + boardCells[0] + " | " + boardCells[1] + " | " + boardCells[2]);
Console.WriteLine("__" + "_" + "__|__" + "_" + "__|__" + "_");
Console.WriteLine(" " + " " + " | " + " " + " | " + " ");
Console.WriteLine(" " + boardCells[3] + " | " + boardCells[4] + " | " + boardCells[5]);
Console.WriteLine("__" + "_" + "__|__" + "_" + "__|__" + "_");
Console.WriteLine(" " + " " + " | " + " " + " | " + " ");
Console.WriteLine(" " + boardCells[6] + " | " + boardCells[7] + " | " + boardCells[8]);
Console.WriteLine(" " + " " + " | " + " " + " | " + " ");
}
public bool playerOneWinCheck(ref int score)
{
bool check = false;
if (boardCells[0] == 'X' && boardCells[1] == 'X' && boardCells[2] == 'X')
{
check = true;
score++;
}
if (boardCells[3] == 'X' && boardCells[4] == 'X' && boardCells[5] == 'X')
{
check = true;
score++;
}
if (boardCells[6] == 'X' && boardCells[7] == 'X' && boardCells[8] == 'X')
{
check = true;
score++;
}
if (boardCells[0] == 'X' && boardCells[3] == 'X' && boardCells[6] == 'X')
{
check = true;
score++;
}
if (boardCells[1] == 'X' && boardCells[4] == 'X' && boardCells[7] == 'X')
{
check = true;
score++;
}
if (boardCells[2] == 'X' && boardCells[5] == 'X' && boardCells[8] == 'X')
{
check = true;
score++;
}
if (boardCells[0] == 'X' && boardCells[4] == 'X' && boardCells[8] == 'X')
{
check = true;
score++;
}
if (boardCells[6] == 'X' && boardCells[4] == 'X' && boardCells[2] == 'X')
{
check = true;
score++;
}
if (check == true)
return true;
else
return false;
}
public bool CPUWinCheck(ref int score) //Method to check to see if CPU won INCRAMENTS SCORE UP ONE IF ANYTHING HOLDS TRUE
{
bool check = false;
if (boardCells[0] == 'O' && boardCells[1] == 'O' && boardCells[2] == 'O')
{
check = true;
score++;
}
if (boardCells[3] == 'O' && boardCells[4] == 'O' && boardCells[5] == 'O')
{
check = true;
score++;
}
if (boardCells[6] == 'O' && boardCells[7] == 'O' && boardCells[8] == 'O')
{
check = true;
score++;
}
if (boardCells[0] == 'O' && boardCells[3] == 'O' && boardCells[6] == 'O')
{
check = true;
score++;
}
if (boardCells[1] == 'O' && boardCells[4] == 'O' && boardCells[7] == 'O')
{
check = true;
score++;
}
if (boardCells[2] == 'O' && boardCells[5] == 'O' && boardCells[8] == 'O')
{
check = true;
score++;
}
if (boardCells[0] == 'O' && boardCells[4] == 'O' && boardCells[8] == 'O')
{
check = true;
score++;
}
if (boardCells[6] == 'O' && boardCells[4] == 'O' && boardCells[2] == 'O')
{
check = true;
score++;
}
if (check == true)
return true;
else
return false;
}
~TicTacToe()
{
for (int c = 0; c <= 10; c++)
{
boardCells[c] = ''0';
}
boardSpacesUsed = 0;
}
}
public class ThreeD : TicTacToe
{
public void threeDWinCheck(ThreeD boardOne, ThreeD boardTwo, ThreeD boardThree, ref int score) //new function to check to see ThreeD wins
{
if (boardOne.boardCells[0] == 'X' && boardTwo.boardCells[0] == 'X' && boardThree.boardCells[0] == 'X')
{
score++;
Console.WriteLine("did it make it");
}
if (boardOne.boardCells[1] == 'X' && boardTwo.boardCells[1] == 'X' && boardThree.boardCells[1] == 'X')
score++;
if (boardOne.boardCells[2] == 'X' && boardTwo.boardCells[2] == 'X' && boardThree.boardCells[2] == 'X')
score++;
if (boardOne.boardCells[3] == 'X' && boardTwo.boardCells[3] == 'X' && boardThree.boardCells[3] == 'X')
score++;
if (boardOne.boardCells[4] == 'X' && boardTwo.boardCells[4] == 'X' && boardThree.boardCells[4] == 'X')
score++;
if (boardOne.boardCells[5] == 'X' && boardTwo.boardCells[5] == 'X' && boardThree.boardCells[5] == 'X')
score++;
if (boardOne.boardCells[6] == 'X' && boardTwo.boardCells[6] == 'X' && boardThree.boardCells[6] == 'X')
score++;
if (boardOne.boardCells[7] == 'X' && boardTwo.boardCells[7] == 'X' && boardThree.boardCells[7] == 'X')
score++;
if (boardOne.boardCells[8] == 'X' && boardTwo.boardCells[8] == 'X' && boardThree.boardCells[8] == 'X')
score++;
if (boardOne.boardCells[0] == 'X' && boardTwo.boardCells[1] == 'X' && boardThree.boardCells[2] == 'X')
score++;
if (boardOne.boardCells[2] == 'X' && boardTwo.boardCells[1] == 'X' && boardThree.boardCells[0] == 'X')
score++;
if (boardOne.boardCells[3] == 'X' && boardTwo.boardCells[4] == 'X' && boardThree.boardCells[5] == 'X')
score++;
if (boardOne.boardCells[5] == 'X' && boardTwo.boardCells[4] == 'X' && boardThree.boardCells[3] == 'X')
score++;
if (boardOne.boardCells[6] == 'X' && boardTwo.boardCells[7] == 'X' && boardThree.boardCells[8] == 'X')
score++;
if (boardOne.boardCells[8] == 'X' && boardTwo.boardCells[7] == 'X' && boardThree.boardCells[6] == 'X')
score++;
if (boardOne.boardCells[0] == 'X' && boardTwo.boardCells[3] == 'X' && boardThree.boardCells[6] == 'X')
score++;
if (boardOne.boardCells[6] == 'X' && boardTwo.boardCells[3] == 'X' && boardThree.boardCells[0] == 'X')
score++;
if (boardOne.boardCells[1] == 'X' && boardTwo.boardCells[4] == 'X' && boardThree.boardCells[7] == 'X')
score++;
if (boardOne.boardCells[7] == 'X' && boardTwo.boardCells[4] == 'X' && boardThree.boardCells[1] == 'X')
score++;
if (boardOne.boardCells[2] == 'X' && boardTwo.boardCells[5] == 'X' && boardThree.boardCells[8] == 'X')
score++;
if (boardOne.boardCells[8] == 'X' && boardTwo.boardCells[5] == 'X' && boardThree.boardCells[2] == 'X')
score++;
if (boardOne.boardCells[0] == 'X' && boardTwo.boardCells[4] == 'X' && boardThree.boardCells[8] == 'X')
score++;
if (boardOne.boardCells[8] == 'X' && boardTwo.boardCells[4] == 'X' && boardThree.boardCells[0] == 'X')
score++;
if (boardOne.boardCells[2] == 'X' && boardTwo.boardCells[4] == 'X' && boardThree.boardCells[6] == 'X')
score++;
if (boardOne.boardCells[6] == 'X' && boardTwo.boardCells[4] == 'X' && boardThree.boardCells[2] == 'X')
score++;
}
public void CPUThreeDWinCheck(ThreeD boardOne, ThreeD boardTwo, ThreeD boardThree, ref int score) //new function to check CPU ThreeD wins
{
if (boardOne.boardCells[0] == 'O' && boardTwo.boardCells[0] == 'O' && boardThree.boardCells[0] == 'O')
score++;
if (boardOne.boardCells[1] == 'O' && boardTwo.boardCells[1] == 'O' && boardThree.boardCells[1] == 'O')
score++;
if (boardOne.boardCells[2] == 'O' && boardTwo.boardCells[2] == 'O' && boardThree.boardCells[2] == 'O')
score++;
if (boardOne.boardCells[3] == 'O' && boardTwo.boardCells[3] == 'O' && boardThree.boardCells[3] == 'O')
score++;
if (boardOne.boardCells[4] == 'O' && boardTwo.boardCells[4] == 'O' && boardThree.boardCells[4] == 'O')
score++;
if (boardOne.boardCells[5] == 'O' && boardTwo.boardCells[5] == 'O' && boardThree.boardCells[5] == 'O')
score++;
if (boardOne.boardCells[6] == 'O' && boardTwo.boardCells[6] == 'O' && boardThree.boardCells[6] == 'O')
score++;
if (boardOne.boardCells[7] == 'O' && boardTwo.boardCells[7] == 'O' && boardThree.boardCells[7] == 'O')
score++;
if (boardOne.boardCells[8] == 'O' && boardTwo.boardCells[8] == 'O' && boardThree.boardCells[8] == 'O')
score++;
if (boardOne.boardCells[0] == 'O' && boardTwo.boardCells[1] == 'O' && boardThree.boardCells[2] == 'O')
score++;
if (boardOne.boardCells[2] == 'O' && boardTwo.boardCells[1] == 'O' && boardThree.boardCells[0] == 'O')
score++;
if (boardOne.boardCells[3] == 'O' && boardTwo.boardCells[4] == 'O' && boardThree.boardCells[5] == 'O')
score++;
if (boardOne.boardCells[5] == 'O' && boardTwo.boardCells[4] == 'O' && boardThree.boardCells[3] == 'O')
score++;
if (boardOne.boardCells[6] == 'O' && boardTwo.boardCells[7] == 'O' && boardThree.boardCells[8] == 'O')
score++;
if (boardOne.boardCells[8] == 'O' && boardTwo.boardCells[7] == 'O' && boardThree.boardCells[6] == 'O')
score++;
if (boardOne.boardCells[0] == 'O' && boardTwo.boardCells[3] == 'O' && boardThree.boardCells[6] == 'O')
score++;
if (boardOne.boardCells[6] == 'O' && boardTwo.boardCells[3] == 'O' && boardThree.boardCells[0] == 'O')
score++;
if (boardOne.boardCells[1] == 'O' && boardTwo.boardCells[4] == 'O' && boardThree.boardCells[7] == 'O')
score++;
if (boardOne.boardCells[7] == 'O' && boardTwo.boardCells[4] == 'O' && boardThree.boardCells[1] == 'O')
score++;
if (boardOne.boardCells[2] == 'O' && boardTwo.boardCells[5] == 'O' && boardThree.boardCells[8] == 'O')
score++;
if (boardOne.boardCells[8] == 'O' && boardTwo.boardCells[5] == 'O' && boardThree.boardCells[2] == 'O')
score++;
if (boardOne.boardCells[0] == 'O' && boardTwo.boardCells[4] == 'O' && boardThree.boardCells[8] == 'O')
score++;
if (boardOne.boardCells[8] == 'O' && boardTwo.boardCells[4] == 'O' && boardThree.boardCells[0] == 'O')
score++;
if (boardOne.boardCells[2] == 'O' && boardTwo.boardCells[4] == 'O' && boardThree.boardCells[6] == 'O')
score++;
if (boardOne.boardCells[6] == 'O' && boardTwo.boardCells[4] == 'O' && boardThree.boardCells[2] == 'O')
score++;
}
~ThreeD()
{
for (int c = 0; c < 10; c++)
{
boardCells[c] = ''0';
}
}
}
static void Main(string[] args)
{
ThreeD boardOne; //1st of three objects for first board
ThreeD boardTwo; //2nd
ThreeD boardThree; //3rd
int boardSelection = 0; //picks witch object to mark in
int counter = 0; //counter for while loop
int playerOneScore = 0; //score for user
int CPUScore = 0; //score for cpu
int CPUBoardSelection = 0;
Random rand = new Random();
int randomNum = rand.Next(1, 2);
if (randomNum == 1) // if randomNum = 1, user goes first
{
Console.WriteLine("You first");
while (true)
{
boardOne.getBoardCells();
boardTwo.getBoardCells();
boardThree.getBoardCells();
Console.WriteLine("Choose which board you wish to mark in. (1 - 3)"); //promts you to pick board
bool board = false;
是的，编译器正确:你试图使用未赋值的变量:
static void Main(string[] args)
{
// It's just a declaration; no value assigned to boardOne; boardOne contains trash
ThreeD boardOne;
// It's just a declaration; no value assigned to boardTwo; boardTwo contains trash
ThreeD boardTwo;
// It's just a declaration; no value assigned to boardThree; boardThree contains trash
ThreeD boardThree;
....
if (randomNum == 1)
{
Console.WriteLine("You first");
while (true)
{
boardOne.getBoardCells(); // <- And here you're trying to access the trash
应该是这样的:
static void Main(string[] args)
{
// boardOne is declared and assigned
ThreeD boardOne = new ThreeD();
// boardTwo is declared and assigned
ThreeD boardTwo = new ThreeD();
// boardThree is declared and assigned
ThreeD boardThree = new ThreeD();
....
if (randomNum == 1)
{
Console.WriteLine("You first");
while (true)
{
boardOne.getBoardCells(); // <- Quite OK
首先，boardOne、boardTwo和boardThree是变量，在本例中是局部变量作用于Main()方法。像任何其他变量一样，它们需要一个有效的数据类型，在您的例子中，类型是ThreeD类。但这并不能使它们成为对象，只是定义了它们的数据类型。
变量只有在使用该类创建新实例(内存中的新单个对象)时才成为对象。必须初始化:
ThreeD boardOne = new ThreeD();
ThreeD boardTwo = new ThreeD();
ThreeD boardThree = new ThreeD();
这样，当方法getBoardCells()被调用时，每个变量都指向它们所代表的内存对象，该对象包含该方法。如果没有赋值，默认情况下变量等于null。当然，由于null没有getBoardCells()方法，您得到的编译器错误是有意义的。
您需要实例化类:
ThreeD boardOne = new ThreeD();
ThreeD boardTwo = new ThreeD();
ThreeD boardThree = new ThreeD();
如果不这样做，则不能访问非静态类成员。
为了使用局部变量，您必须初始化它:
var boardOne = new ThreeD();
var boardTwo = new ThreeD();
...
你必须初始化你的board对象，因为c#编译器不允许使用未初始化的变量。检查此链接:编译错误CS0165
static void Main(string[] args)
{
ThreeD boardOne = new ThreeD(); //1st of three objects for first board
ThreeD boardTwo = new ThreeD(); //2nd
ThreeD boardThree = new ThreeD();
//..............
// ..............
}
您缺少的创建对象实例
ThreeD boardOne = new ThreeD();
ThreeD boardTwo = new ThreeD();