用C++实现的贪吃蛇游戏

我是一个C++初学者，控制台实现了一个贪吃蛇游戏。

代码如下：

//"贪吃蛇游戏"V1.0
//李国良于2016年12月29日编写完成

#include <iostream>
#include <string>
#include <ctime>
#include <windows.h>
#include <conio.h>

using namespace std;

int food[2] = { 9, 9 };//初始食物坐标
int snake[1000][2];//蛇身坐标
int length = 1;//初始蛇长
int headX, headY;//蛇头坐标
int speed = 500;//游戏难度
int score = 0;//分数
int level = 1;//难度等级
string name;//玩家姓名

void gotoxy(short x, short y);//移动光标
int setdirection(int x);//确定方向变量
void changesnake(int x);//改变蛇身坐标
void ifchangefood();//判断蛇是否吃到食物
void makefood();//创造新食物
bool judgelife();//判断蛇是否存活
void drawsnake();//画蛇
void drawfood();//画食物
void drawwall();//画墙
void drawscore();//画数据
void draw();//绘图

int main()
{
	SetConsoleTitle("贪吃蛇游戏");
	int po = 2;//初始方向变量
	snake[0][0] = 7;
	snake[0][1] = 7;//初始蛇头坐标
	headX = snake[0][0];
	headY = snake[0][1];
	gotoxy(30, 7);
	cout << "欢迎来到贪吃蛇游戏";
	gotoxy(30, 9);
	cout << "作者：李国良 版本1.0";
	gotoxy(30, 11);
	cout << "请输入你的姓名：";
	cin >> name;
	system("cls");
	gotoxy(30, 7);
	cout << "游戏控制方式:";
	gotoxy(30, 9);
	cout << "W键:向上 S键:向下";
	gotoxy(30, 11);
	cout << "A键:向左 D键:向右";
	gotoxy(30, 13);
	cout << "空格键:暂停";
	gotoxy(30, 15);
	cout << "将游戏窗口最大化之后";
	gotoxy(30, 17);
	cout << "按回车键开始游戏...";
	cin.get();
	cin.get();
	system("cls");
	while (true)
	{
		po = setdirection(po);
		system("cls");
		changesnake(po);
		ifchangefood();
		if (!judgelife())
			break;
		draw();
		Sleep(speed);
	}
	gotoxy(30, 10);
	cout << "Game Over!!!";
	Sleep(2000);
	gotoxy(28, 12);
	system("pause");
	return 0;
}

void gotoxy(short x, short y)
{
	COORD position = { x, y };
	HANDLE hOut = GetStdHandle(STD_OUTPUT_HANDLE);
	SetConsoleCursorPosition(hOut, position);
}

int setdirection(int x)
{
	char ch;
	if (_kbhit())
	{
		ch = _getch();
		switch (ch)
		{
		case 'w':
			x = 1;
			break;
		case 's':
			x = 2;
			break;
		case 'a':
			x = 3;
			break;
		case 'd':
			x = 4;
			break;
		case ' ':
			gotoxy(37, 16);
			cout << "游  戏  暂  停. . .";
			gotoxy(37, 18);
			system("pause");
			break;
		default:
			break;
		}
	}
	return x;
}

void changesnake(int x)
{
	switch (x)
	{
	case 1:
		headY -= 1;
		break;
	case 2:
		headY += 1;
		break;
	case 3:
		headX -= 1;
		break;
	case 4:
		headX += 1;
		break;
	default:
		break;
	}
	for (int i = length; i > 0; --i)
	{
		for (int j = 0; j < 2; ++j)
		{
			snake[i][j] = snake[i - 1][j];
		}
	}
	snake[0][0] = headX;
	snake[0][1] = headY;
}

void ifchangefood()
{
	if (snake[0][0] == food[0] && snake[0][1] == food[1])
	{
		length++;
		makefood();
		++score;
		if (length > 5)
		{
			speed = 450;
			level = 2;
		}
		if (length > 10)
		{
			speed = 400;
			level = 3;
		}
		if (length > 15)
		{
			speed = 350;
			level = 4;
		}
		if (length > 20)
		{
			speed = 300;
			level = 5;
		}
		if (length > 25)
		{
			speed = 250;
			level = 6;
		}
		if (length > 30)
		{
			speed = 200;
			level = 7;
		}
		if (length > 35)
		{
			speed = 150;
			level = 8;
		}
		if (length > 40)
		{
			speed = 100;
			level = 9;
		}
		if (length > 45)
		{
			speed = 50;
			level = 10;
		}
	}
}

void makefood()
{
	srand((unsigned)time(NULL));
	food[0] = rand() % 30 + 2;
	food[1] = rand() % 30 + 4;
	for (int m = 0; m < length; ++m)
	{
		if (food[0] == snake[m][0] && food[1] == snake[m][1])
		{
			makefood();
			break;
		}
	}
}

bool judgelife()
{
	for (int x = 1; x < length; ++x)
	{
		if (headX == snake[x][0] && headY == snake[x][1])
		{
			return false;
		}

	}
	if (headX < 1 || headY < 3 || headX > 34 || headY > 34)
		return false;
	else
		return true;
}

void drawsnake()
{
	gotoxy(snake[0][0], snake[0][1]);
	cout << "@";
	for (int n = 1; n < length; ++n)
	{
		gotoxy(snake[n][0], snake[n][1]);
		cout << "#";
	}
}

void drawfood()
{
	gotoxy(food[0], food[1]);
	cout << "$";
}

void drawwall()
{
	gotoxy(0, 0);
	cout << "------------------------------------";
	gotoxy(16, 1);
	cout << "贪吃蛇";
	gotoxy(0, 2);
	cout << "++++++++++++++++++++++++++++++++++++";
	gotoxy(0, 35);
	cout << "------------------------------------";
	for (int x = 0; x < 35; ++x)
	{
		gotoxy(0, x);
		cout << "|";
		gotoxy(35, x);
		cout << "|";
	}
}

void drawscore()
{
	gotoxy(37, 10);
	cout << "分数：" << score;
	gotoxy(37, 12);
	cout << "等级：" << level;
	gotoxy(37, 14);
	cout << "玩家姓名：" << name;
}

void draw()
{
	drawsnake();
	drawfood();
	drawwall();
	drawscore();
}

控制台游戏运行起来屏幕有点闪烁。。。