进程状态转换及其PCB的变化

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代码实现了模拟进程状态转换及其相应PCB内容、组织结构的变化。
#include<iostream>using namespace std;typedef struct pcb{    int id;    struct pcb *next;}pcb;pcb *ready,*run,*block;pcb* cre()//创建带头结点的ready队列{    pcb *head=new pcb;    head->next=NULL;    pcb *q=head;    int n;    cout<<"输入进程数:\n";    cin>>n;    for(int i=0;i<n;i++)    {        pcb *p=new pcb;        cin>>p->id;        p->next=NULL;        q->next=p;        q=p;    }    return head;}void ins(pcb *head,pcb *node)//插入节点{    pcb *p=head;    while(p->next)    {        p=p->next;    }    pcb *n=new pcb;    n->id=node->id;    p->next=n;    n->next=NULL;}void del(pcb *head){    pcb *p=head->next;    if(p)    {    head->next=head->next->next;    delete p;    }}void dis(){    pcb *p;    p=ready->next;    cout<<"ready:\t";    while(p)    {        cout<<p->id<<" ";        p=p->next;    }    cout<<endl;    p=run->next;    cout<<"run  :\t";    while(p)    {        cout<<p->id<<" ";        p=p->next;    }    cout<<endl;    p=block->next;    cout<<"block:\t";    while(p)    {        cout<<p->id<<" ";        p=p->next;    }    cout<<endl;}int main(){    ready=cre();    run=new pcb;    run->next=NULL;    block=new pcb;    block->next=NULL;    dis();    int i;    cout<<"chose:\t1:ready->run\t2:run->ready\t3:run->block\t4:block->ready\n";    while(cin>>i)    {        if(i==1)        {            if(ready->next)            {                if(run->next)                {                    ins(block,run->next);                    del(run);                }                ins(run,ready->next);                del(ready);            }            else            {                if(block->next)                {                    ins(block,run->next);                    del(run);                    ins(run,block->next);                    del(block);                }            }        }        else if(i==2)        {            if(run->next)            {                if(ready->next)                {                    ins(ready,run->next);                    del(run);                    ins(run,ready->next);                    del(ready);                }            }        }        else if(i==3)        {            if(run->next)            {                if(ready->next)                {                    ins(block,run->next);                    ins(run,ready->next);                    del(run);                    del(ready);                }                else                {                    ins(block,run->next);                    ins(run,block->next);                    del(block);                    del(run);                }            }        }        else if(i==4)        {            if(block->next)            {                ins(ready,block->next);                del(block);            }        }        else            break;        dis();        cout<<"chose:\t1:ready->run\t2:run->ready\t3:run->block\t4:block->ready\n";    }    return 0;}
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