我使用ＴURBO C++ 2.0或3.0调试一个操作系统上机例题,编译时总在#include<iostream.h>句上提示error Must use C++ for the type iostream.错误，不知为何，请于赐教，不胜感谢．急急急！！！

原程序如下：
#include<stdio.h>
#include <dos.h>
#include<stdlib.h>
#include<conio.h>
#include<iostream.h>
#define P_NUM 5
#define P_TIME 50
enum state{
ready,
execute,
block,
finish
};

struct pcb{
char name[4];
int priority;
int cputime;
int needtime;
int count;
int round;
state process;
pcb * next;
};
pcb * get_process();
pcb * get_process(){
pcb *q;
pcb *t;
pcb *p;
int i=0;
cout<<"input name and time"<<endl;

while (i<P_NUM){
q=(struct pcb *)malloc(sizeof(pcb));
cin>>q->name;
cin>>q->needtime;
q->cputime=0;
q->priority=P_TIME-q->needtime;
q->process=ready;
q->next=NULL;
if (i==0){
p=q;
t=q;
}
else{
t->next=q;
t=q;
}
i++;
} //while
return p;
}
void display(pcb *p){
cout<<"name"<<" "<<"cputime"<<" "<<"needtime"<<" "<<"priority"<<" "<<"state"<<endl;
while(p){
cout<<p->name;
cout<<" ";
cout<<p->cputime;
cout<<" ";
cout<<p->needtime;
cout<<" ";
cout<<p->priority;
cout<<" ";
switch(p->process){
case ready:cout<<"ready"<<endl;break;
case execute:cout<<"execute"<<endl;break;
case block:cout<<"block"<<endl;break;
case finish:cout<<"finish"<<endl;break;
}
p=p->next;
}
}

int process_finish(pcb *q){
int bl=1;
while(bl&&q){
bl=bl&&q->needtime==0;
q=q->next;
}
return bl;
}

void cpuexe(pcb *q){
pcb *t=q;
int tp=0;
while(q){
if (q->process!=finish){
q->process=ready;
if(q->needtime==0){
q->process=finish;
}
}
if(tp<q->priority&&q->process!=finish){
tp=q->priority;
t=q;
}
q=q->next;
}
if(t->needtime!=0){
t->priority-=3;
t->needtime--;
t->process=execute;
t->cputime++;
}
}

void priority_cal(){
pcb * p;
clrscr();
p=get_process();
int cpu=0;
clrscr();
while(!process_finish(p)){
cpu++;
cout<<"cputime:"<<cpu<<endl;
cpuexe(p);
display(p);
sleep(2);
clrscr();
}
printf("All processes have finished,press any key to exit");
getch();
}

void display_menu(){
cout<<"CHOOSE THE ALGORITHM:"<<endl;
cout<<"1 PRIORITY"<<endl;
cout<<"2 ROUNDROBIN"<<endl;
cout<<"3 EXIT"<<endl;
}
pcb * get_process_round(){
pcb *q;
pcb *t;
pcb *p;
int i=0;
cout<<"input name and time"<<endl;

while (i<P_NUM){
q=(struct pcb *)malloc(sizeof(pcb));
cin>>q->name;
cin>>q->needtime;
q->cputime=0;
q->round=0;
q->count=0;
q->process=ready;
q->next=NULL;
if (i==0){
p=q;
t=q;
}
else{
t->next=q;
t=q;
}
i++;
} //while
return p;
}

void cpu_round(pcb *q){
q->cputime+=2;
q->needtime-=2;
if(q->needtime<0) {
q->needtime=0;
}
q->count++;
q->round++;
q->process=execute;

}

pcb * get_next(pcb * k,pcb * head){
pcb * t;
t=k;
do{
t=t->next;
}
while (t && t->process==finish);

if(t==NULL){
t=head;

while (t->next!=k && t->process==finish){
t=t->next;
}
}
return t;
}
void set_state(pcb *p){
while(p){
if (p->needtime==0){
p->process=finish;

}
if (p->process==execute){
p->process=ready;
}
p=p->next;
}
}
void display_round(pcb *p){
cout<<"NAME"<<" "<<"CPUTIME"<<" "<<"NEEDTIME"<<" "<<"COUNT"<<" "<<"ROUND"<<" "<<"STATE"<<endl;
while(p){
cout<<p->name;
cout<<" ";
cout<<p->cputime;
cout<<" ";
cout<<p->needtime;
cout<<" ";
cout<<p->count;
cout<<" ";
cout<<p->round;
cout<<" ";
switch(p->process){
case ready:cout<<"ready"<<endl;break;
case execute:cout<<"execute"<<endl;break;
case finish:cout<<"finish"<<endl;break;
}
p=p->next;
}
}

void round_cal(){
pcb * p;
pcb * r;
clrscr();
p=get_process_round();
int cpu=0;
clrscr();
r=p;
while(!process_finish(p)){
cpu+=2;
cpu_round(r);
r=get_next(r,p);
cout<<"cpu "<<cpu<<endl;
display_round(p);
set_state(p);
sleep(5);
clrscr();
}
}

void main(){
display_menu();
int k;
scanf("%d",&k);
switch(k){
case 1:priority_cal();break;
case 2:round_cal();break;
case 3:break;
display_menu();
scanf("%d",&k);
}
}