进程调度（C/C++语言写法）

 

按照这个实验，我用C++写了一个程序，就是进程调度的程序。下面是代码：（很多注释，希望你们能够看懂）

#include<iostream>
#include<string>
#include<fstream>
#include<windows.h>

using namespace std;

struct PCB {
	string name;//进程名
	struct PCB *next;//指针
	int time;//运行时间
	int grade;//优先级
	string state;//状态
};



PCB *head;//进程队列的头

int couter = 1;//计算第几次运行

char choose;//用来判断用户是否申请资源


void init();//初始化
void output();//打印进程调用的情况
void ReSort(PCB *p);//重新对进程队列排序
void Print();//打印
void ReadIn();
void WriteOut();
void Request();


int main() {
	init();
	output();

	return 0;
}

void init() {
	ReadIn();
	Print();
	system("pause");

}

void output() {

	PCB *p = head;

	system("cls"); 
	cout<<"第"<<couter<<"次运行："<<endl;
	cout<<"当前运行的进程:"<<p->name<<endl;

	//Print();


	p->grade = p->grade - 1;//运行后优先级-1
	p->time = p->time - 1; //运行后运行时间-1
	couter++;

	if(head->next != NULL && p->time != 0) {//如果不为尾节点，当前的运行时间不为0，把头节点独立出来，重新按优先级排序

	//	cout<<"重新排序之前：\n\n";
		Print();

		PCB *work = head;//把头节点独立出来
		head = head->next;//将头指针指向第二节点
		PCB *p = head;
		PCB *temp = head;//用来保存上一节点

		//按优先级，插入排序
		while(p != NULL) {
			if(p->grade >= work->grade && p->next == NULL) {//如果当前节点大于或者等于独立出来的节点，且当前只有一个节点
				p->next = work;
				work->next = NULL;
				break;
			} else if(p->grade >= work->grade && p->next->grade <= work->grade) { //如果当前进程的优先级大于或者等于独立出来的节点，且当前节点的下一个节点的优先级小于或者等于独立出来的节点
				work->next = p->next;
				p->next = work;
				break;
			} else if(p->grade < work->grade) { //如果当前节点比独立的节点要小
				work->next = p;
				head = work;
				break;
			}
			temp = p;//保留当前节点
			p = p->next;
		}
		//cout<<"重新排序之后：\n\n";
		//Print();
	}
	
	
	else if(head->next == NULL && head->time != 0){//如果当前为最后一个进程，且运行时间不为0 
		Print();
	}



	else if(head->time == 0) {//如果当前进程的运行时间为0
		if(head->next != NULL) { //如果当前不是最后一个结束的节点
			head->state = "结束";
			Print();
			head = head->next;
		} else if(head->next == NULL) { //如果当前为最后一个结束的点
			head->state = "结束";
			Print();
			cout<<"所有进程均已完成！"<<endl;
			exit(0);
		}
	}



	if(choose != 'k') {
		cout<<"你想申请新的进程吗？(y申请)/(n不申请)/(k不再申请)"<<endl;
		cin>>choose;
		if(choose == 'y' || choose == 'Y') {
			ReSort(p);
		}
	}

	output();//递归调用
}

void ReSort(PCB *p) {

	PCB *temp = new PCB;
	temp->next = NULL;
	cout<<"请输入进程名：";
	cin>>temp->name;
	cout<<"请输入进程运行时间:";
	cin>>temp->time;
	cout<<"请输入进程优先级：";
	cin>>temp->grade;
	temp->state = "就绪";
	//重新排序

	p = head;
	PCB *last = head;//用来保存上一节点
	while(p != NULL) {
		if(p->grade >= temp->grade && p->next->grade <= temp->grade) {
			temp->next = p->next;
			p->next = temp;
			break;
		} else if(p->grade >= temp->grade && p->next == NULL) {
			p->next = temp;
			temp->next = NULL;
			break;
		} else if(p->grade < temp->grade) {
			temp->next = p;
			head = temp;
			break;
		}
		last = p;//保留当前节点
		p = p->next;
	}
	//调试
	Print();//打印
	
	WriteOut();
	system("pause");

}



void ReadIn() {
	ifstream inputfile;
	inputfile.open("进程调度.txt");

	head = new PCB;
	PCB *p = head;
	while(inputfile) {
		inputfile>>p->name>>p->time>>p->grade>>p->state;
		p->next = NULL;
		if(inputfile.peek() == EOF) break;//判断文件尾巴字符，到了尾巴，退出循环
		p->next = new PCB;
		p = p->next;
	}
}

void WriteOut() {
	PCB *p = head;
	ofstream outputfile;
	outputfile.open("进程调度.txt");
	while(p != NULL) {
//		if(p->next != NULL)outputfile<<p->name<<" "<<p->time<<" "<<p->grade<<" "<<p->state<<"\n";
//		else outputfile<<p->name<<" "<<p->time<<" "<<p->grade<<" "<<p->state;
		outputfile<<p->name<<" "<<p->time<<" "<<p->grade<<" "<<p->state;
		if(p->next != NULL)outputfile<<"\n";
		p = p->next;
	}
}

void Print() {
	//system("cls");
	cout<<"------------------------------------------------------------"<<endl;
	cout<<"当前进程队列\n";
	PCB *p = head;
	cout<<"进程名字    运行时间    优先级数    进程状态\n" ;
	while(p != NULL) {
		cout<<p->name<<"            ";
		cout<<p->time<<"            ";
		cout<<p->grade<<"            ";
		cout<<p->state<<endl;
		p = p->next;
	}
	cout<<"------------------------------------------------------------"<<endl<<endl;
	cout<<"正在进入运行下一个进程。。。。\n\n";
	Sleep(1500);
}