贪吃蛇：：为什么我的蛇会断？

#include<iostream>
#include<ctime>
#include<string>
#include<conio.h>
using namespace std;
#define MapHeight 40
#define MapWidth 40
#define MaxSize 100
string Map[MapHeight][MapWidth];
//坐标（x，y）
struct Coord
{
	int X;
	int Y;
	bool operator==(Coord c)
	{
		return (c.X) == X && (c.Y == Y);
	}
	Coord(int x, int y)
	{
		X = x;
		Y = y;
	}
};
//其中记录着蛇的长度，以及每一段蛇的坐标
class Snake
{
public:
	int Length;
	int m_X[MaxSize];
	int m_Y[MaxSize];
	Snake()
	{
		Length = 3;
	}
}snake;
//其中记录着食物的坐标
class Food
{
public:
	int m_X;
	int m_Y;
}food;
//如果 食物的坐标 与 任意一个蛇体坐标 都不相等则输出1，视为符合条件
class Compare
{
public:
	bool operator()(int a,int b)
	{
		Coord C(a, b);
		bool judge=1;
		bool temp;
		for (int i = 0; i < snake.Length; i++)
		{
			Coord c = Coord(snake.m_X[i], snake.m_Y[i]);
			temp = !(c == C);
			judge = judge && temp;
		}
		return judge;
	}
}compare;
//------------------------------------------------------------------------------------------------------------------------------
void PrintMap(string arr[MapHeight][MapWidth])
{
	for (int i = 0; i < 40; i++)
	{
		for (int j = 0; j < 40; j++)
		{
			cout << arr[i][j];
		}
		cout << endl;
	}
}
//------------------------------------------------------------------------------------------------------------------------------
void EvaluateSnake(Snake s)
{
	for (int i = 0; i < s.Length; i++)
	{
		Map[s.m_X[i]][s.m_Y[i]] = "■";
	}
}
//------------------------------------------------------------------------------------------------------------------------------

//------------------------------------------------------------------------------------------------------------------------------
void CreateFood()
{
	food.m_X = rand() % (MapHeight - 2) + 1;
	food.m_Y = rand() % (MapWidth - 2) + 1;
	for (int i = 0; !compare(food.m_X, food.m_Y); i++)
	{
		food.m_X = rand() % (MapHeight - 2) + 1;
		food.m_Y = rand() % (MapWidth - 2) + 1;
	}
	Map[food.m_X][food.m_Y] = "⊙";
}
//---------------------------------------------------------------------------------------
int main()
{
	srand((unsigned int)time(NULL));
	//1·地图的初始化-----------------------------------------------------------------------------------------------------------
	for (int i = 0; i < 40; i++)
	{
		for (int j = 0; j < 40; j++)
		{
			Map[i][j] = "  ";
		}
	}
	for (int i = 0; i < 40; i++)
	{
		if (i == 0 || i == 39)
		{
			for (int j = 0; j < 40; j++)
			{
				Map[i][j] = "■";
			}
		}
		else
		{
			for (int j = 0; j < 40; j++)
			{
				Map[i][j] = "  ";
				if (j == 0 || j == 39)
				{
					Map[i][j] = "■";
				}
			}
		}
	}
	//2·蛇的初始化-------------------------------------------------------------------------------------------------------------
	snake.m_X[0] = rand() % (MapHeight - 19) + 10;
	snake.m_Y[0] = rand() % (MapWidth - 19) + 10;
	int judge = rand() % 4;
	if (judge == 0)
	{
		for (int i = 1; i <= 2; i++)
		{
			snake.m_X[i] = snake.m_X[i - 1];
			snake.m_Y[i] = snake.m_Y[i - 1]+1;
		}
	}
	else if (judge == 1)
	{
		for (int i = 1; i <= 2; i++)
		{
			snake.m_X[i] = snake.m_X[i - 1];
			snake.m_Y[i] = snake.m_Y[i - 1] - 1;
		}
	}
	else if (judge == 2)
	{
		for (int i = 1; i <= 2; i++)
		{
			snake.m_X[i] = snake.m_X[i - 1] + 1;
			snake.m_Y[i] = snake.m_Y[i - 1];
		}
	}
	else
	{
		for (int i = 1; i <= 2; i++)
		{
			snake.m_X[i] = snake.m_X[i - 1] - 1;
			snake.m_Y[i] = snake.m_Y[i - 1];
		}
	}
	for (int i = 0; i < snake.Length; i++)
	{
		Map[snake.m_X[i]][snake.m_Y[i]] = "■";
	}
	//3·食物的初始化-----------------------------------------------------------------------------------------------------------
	CreateFood();
	//--------------------------------------------------------------------------------------------------------------------------
	//范例轮回




	while (true)
	{
		PrintMap(Map);
		int key = _getch();
		switch (key)
		{
		case 119:
			if (snake.m_X[0] == snake.m_X[1])
			{
				snake.m_X[0] -= 1;
				Map[snake.m_X[snake.Length - 1]][snake.m_Y[snake.Length - 1]] = "  ";
				for (int i = snake.Length - 1; i > 0; i--)
				{
					snake.m_X[i] = snake.m_X[i - 1];
					snake.m_Y[i] = snake.m_Y[i - 1];
				}
				EvaluateSnake(snake);
				break;
			}
			else
			{
				break;
			}
			
		case 115:
			break;
		case 97:
			break;
		case 100:
			break;
		default:
			break;
		}
		system("cls");
	}
}

我只写了w即向上，如果蛇也朝上，那就会断开，我不知道为什么

查完了。在移动的时候你的逻辑有点问题。现在蛇移动的时候就不会断链子了。

#include<iostream>
#include<ctime>
#include<string>
#include<conio.h>
using namespace std;
#define MapHeight 40
#define MapWidth 40
#define MaxSize 100
string Map[MapHeight][MapWidth];
//坐标（x，y）
struct Coord
{
	int X;
	int Y;
	bool operator==(Coord c)
	{
		return (c.X) == X && (c.Y == Y);
	}
	Coord(int x, int y)
	{
		X = x;
		Y = y;
	}
};
//其中记录着蛇的长度，以及每一段蛇的坐标
class Snake
{
public:
	int Length;
	int m_X[MaxSize];
	int m_Y[MaxSize];
	Snake()
	{
		Length = 3;
	}
}snake;
//其中记录着食物的坐标
class Food
{
public:
	int m_X;
	int m_Y;
}food;
//如果 食物的坐标 与 任意一个蛇体坐标 都不相等则输出1，视为符合条件
class Compare
{
public:
	bool operator()(int a,int b)
	{
		Coord C(a, b);
		bool judge=1;
		bool temp;
		for (int i = 0; i < snake.Length; i++)
		{
			Coord c = Coord(snake.m_X[i], snake.m_Y[i]);
			temp = !(c == C);
			judge = judge && temp;
		}
		return judge;
	}
}compare;
//------------------------------------------------------------------------------------------------------------------------------
void PrintMap(string arr[MapHeight][MapWidth])
{
	for (int i = 0; i < 40; i++)
	{
		for (int j = 0; j < 40; j++)
		{
			cout << arr[i][j];
		}
		cout << endl;
	}
}
//------------------------------------------------------------------------------------------------------------------------------
void EvaluateSnake(Snake s)
{
	for (int i = 0; i < s.Length; i++)
	{
		Map[s.m_X[i]][s.m_Y[i]] = "■";
	}
}
//------------------------------------------------------------------------------------------------------------------------------

//------------------------------------------------------------------------------------------------------------------------------
void CreateFood()
{
	food.m_X = rand() % (MapHeight - 2) + 1;
	food.m_Y = rand() % (MapWidth - 2) + 1;
	for (int i = 0; !compare(food.m_X, food.m_Y); i++)
	{
		food.m_X = rand() % (MapHeight - 2) + 1;
		food.m_Y = rand() % (MapWidth - 2) + 1;
	}
	Map[food.m_X][food.m_Y] = "⊙";
}
void InitMap()
{
    //1·地图的初始化-----------------------------------------------------------------------------------------------------------
    for (int i = 0; i < 40; i++)
	{
		for (int j = 0; j < 40; j++)
		{
			Map[i][j] = "  ";
		}
	}
	for (int i = 0; i < 40; i++)
	{
		if (i == 0 || i == 39)
		{
			for (int j = 0; j < 40; j++)
			{
				Map[i][j] = "■";
			}
		}
		else
		{
			for (int j = 0; j < 40; j++)
			{
				Map[i][j] = "  ";
				if (j == 0 || j == 39)
				{
					Map[i][j] = "■";
				}
			}
		}
	}
}


//---------------------------------------------------------------------------------------
int main()
{
	srand((unsigned int)time(NULL));
	InitMap();
	//2·蛇的初始化-------------------------------------------------------------------------------------------------------------
	snake.m_X[0] = rand() % (MapHeight - 19) + 10;
	snake.m_Y[0] = rand() % (MapWidth - 19) + 10;
	int judge = rand() % 4;
	if (judge == 0)
	{
		for (int i = 1; i <= 2; i++)
		{
			snake.m_X[i] = snake.m_X[i - 1];
			snake.m_Y[i] = snake.m_Y[i - 1]+1;
		}
	}
	else if (judge == 1)
	{
		for (int i = 1; i <= 2; i++)
		{
			snake.m_X[i] = snake.m_X[i - 1];
			snake.m_Y[i] = snake.m_Y[i - 1] - 1;
		}
	}
	else if (judge == 2)
	{
		for (int i = 1; i <= 2; i++)
		{
			snake.m_X[i] = snake.m_X[i - 1] + 1;
			snake.m_Y[i] = snake.m_Y[i - 1];
		}
	}
	else
	{
		for (int i = 1; i <= 2; i++)
		{
			snake.m_X[i] = snake.m_X[i - 1] - 1;
			snake.m_Y[i] = snake.m_Y[i - 1];
		}
	}
	for (int i = 0; i < snake.Length; i++)
	{
		Map[snake.m_X[i]][snake.m_Y[i]] = "■";
	}
	//3·食物的初始化-----------------------------------------------------------------------------------------------------------
	CreateFood();
	//--------------------------------------------------------------------------------------------------------------------------
	//范例轮回

    EvaluateSnake(snake);


    int head_x, head_y;
	while (true)
	{
		PrintMap(Map);
		int key = _getch();
		switch (key)
		{
		case 'w':
		    head_x = snake.m_X[snake.Length-1], head_y = snake.m_Y[snake.Length-1];
		    for(int i = 0; i < snake.Length-1; i++){
                snake.m_X[i] = snake.m_X[i+1];
                snake.m_Y[i] = snake.m_Y[i+1];
		    }
		    snake.m_X[snake.Length-1] = head_x - 1;
		    snake.m_Y[snake.Length-1] = head_y;
		    InitMap();
            EvaluateSnake(snake);
            Map[food.m_X][food.m_Y] = "⊙";
            break;
        case 115:
			break;
		case 97:
			break;
		case 100:
			break;
		default:
			break;
		}
		system("cls");
	}
}

另外，按照你这个写法，接下来的其他逻辑也可能会写着写着遇到困难，建议把蛇的身体修改为用vector容器储存的从头到尾的坐标，以便于移动、增加长度时候的判断。如果有其他问题，欢迎私信与我讨论。

哈哈哈哈好问题，我帮你查一下哈。