我为我的主题编写了一个程序，用C语言编写的OS时间调度程序。我刚刚开始，但我的问题是如何显示GANTT图表。而且我对抢先先到先得，先到先得有点混淆。我理解它是如何工作的，但是当它到来时，如果到达时间是......
PROCESS BURST TIME ARRIVAL TIME START WAITING FINISH TURN AROUND TIME
P1 12 2 ?????
P2 6 1 ?????
P3 9 0 ?????
但如果到达时间从0开始，我知道如何回答......
PROCESS BURST TIME ARRIVAL TIME START WAITING FINISH TURN AROUND TIME
P1 12 0 0 0 12 12
P2 6 1 12 11 18 17
P3 9 4 18 14 27 23
average waiting time = 8.33
average turn around time= 17.33
这里是我的代码，我刚刚将一些代码发送到了互联网上。它还没有完成我的FCFS代码......
#include <stdio.h>
#include <stdlib.h>
//FCFS
void npefcfs();
void pefcfs();
void fcfs();
//MENU
void menu();
//y/n statement
void backq();
int main()
{
menu();
system("pause");
return 0;
}
void menu()
{
int choose;
printf(" MENU OS Time Scheduling Discipline");
printf("\n ---------------------------------------------------");
printf("\n [1] (FCFS)First Come, First Serve");
printf("\n [2] (SJF)Shortest Job First");
printf("\n [3] (SRT)Shortest Remaining Time");
printf("\n [4] (RR)Round-robin Scheduling");
printf("\n [5] (MLQ)Multilevel queue scheduling");
printf("\n [6] Priority");
printf("\n [7] EXIT");
printf("\n\nEnter your choice: ");
scanf("%d", &choose);
switch (choose)
{
case 1:
system("cls");
fcfs();
break;
case 7:
break;
default:
system("cls");
printf("Please Enter Correct Value!\n\n");
menu();
break;
}
}
//y/n statement
void backq()
{
char choice2;
printf("Do you like another try? y/n, Y/N: ");
scanf("%s", &choice2);
switch (choice2)
{
case 'y':
system("cls");
menu();
break;
case 'Y':
system("cls");
menu();
break;
case 'n':
system("exit");
break;
case 'N':
system("exit");
break;
default:
system("cls");
printf("\nPlease Enter a coorect value!");
backq();
break;
}
}
//fcfs menu
void fcfs()
{
int choice;
printf("FIRST COME, FIRST SERVE");
printf("\n-----------------------------");
printf("\n [1] Non Pre-emptive");
printf("\n [2] Pre-emptive");
printf("\n [3] BACK");
printf("\n [4] Exit");
printf("\nPlease your choice: ");
scanf("%d",&choice);
switch (choice)
{
case 1:
system("cls");
npefcfs();
break;
case 2:
system("cls");
pefcfs();
break;
case 3:
system("cls");
menu();
break;
case 4:
break;
default:
break;
}
}
//function for non pre-emptive fcfs
void npefcfs()
{
//declaration
int process;
int bt[10], at[10], start[10], wait[10], fnsh[10], ta[10];
int i, a, sum = 0;
float awt=0.0, att=0.0;
start[0] = 0;
//how many process
printf("How many process do you like to use: ");
scanf("%d",&process);
printf("\n-----------------------------------------");
printf("\nPlease Enter Burst time: \n\n");
//for declaring zero to at[] array
for(i=0; i<process; i++)
{
at[i]=0;
}
//enter burst time depending on how many process
for (i = 0, a=1; i < process,a<=process; i++,a++)
{
printf("P%d =",a);
scanf("%d", &bt[i]);
}
//for calculation of fcfs
for(i=0; i<process; i++)
{
sum=0;
for(a=0; a<i; a++)
{
sum=sum+bt[a];
start[i]=sum;
}
}
//for calculation of start,wait,finish,turn around time, average waiting time and average turn around time
for(i=0; i<process; i++)
{
wait[i] = start[i];
fnsh[i] = bt[i]+start[i];
ta[i] = fnsh[i];
awt+=wait[i];
att+=ta[i];
}
//computation
awt/=process;
att/=process;
//output in table like form
printf("\n\tProcess\tBT\tAT\tSTART\tWAIT\tFINISH\tTA");
printf("\n\t-------\t--\t--\t-----\t----\t------\t--");
for(i=0; i<process; i++)
{
printf("\n\tP%d\t%d\t%d\t%d\t%d\t%d\t%d", (i+1),bt[i],at[i],start[i],wait[i],fnsh[i],ta[i]);
}
printf("\n\nAverage Waiting Time: %f", awt);
printf("\nAverage Turn Around Time: %f\n",att);
backq();
}
//function for pre-emptive fcfs
void pefcfs()
{
//declaration
int process;
int bt[10], at[10], start[10], wait[10], fnsh[10], ta[10];
int i, a, sum = 0;
float awt=0.0, att=0.0;
start[0] = 0;
//how many process
printf("How many process do you like to use: ");
scanf("%d",&process);
printf("\n-----------------------------------------");
printf("\nPlease Enter Burst Time: \n\n");
//enter burst time depending on how many process
for (i = 0, a=1; i < process,a<=process; i++,a++)
{
printf("P%d =",a);
scanf("%d", &bt[i]);
}
printf("\nPlease Enter Arrival Time: \n");
//enter arrival time
for(i=0; i<process; i++)
{
printf("AT%d =", (i+1));
scanf("%d", &at[i]);
}
//for calculation of fcfs
for(i=0; i<process; i++)
{
sum=0;
for(a=0; a<i; a++)
{
sum=sum+bt[a];
start[i]=sum;
}
}
//for calculation of start,wait,finish,turn around time, average waiting time and average turn around time
for(i=0; i<process; i++)
{
wait[i] = start[i]-at[i];
fnsh[i] = bt[i]+start[i];
ta[i] = fnsh[i]-at[i];
awt+=wait[i];
att+=ta[i];
}
//computation
awt/=process;
att/=process;
//output in table like form
printf("\n\tProcess\tBT\tAT\tSTART\tWAIT\tFINISH\tTA");
printf("\n\t-------\t--\t--\t-----\t----\t------\t--");
for(i=0; i<process; i++)
{
printf("\n\tP%d\t%d\t%d\t%d\t%d\t%d\t%d", (i+1),bt[i],at[i],start[i],wait[i],fnsh[i],ta[i]);
}
printf("\n\nAverage Waiting Time: %f", awt);
printf("\nAverage Turn Around Time: %f\n",att);
backq();
}
我不知道如何根据突发时间显示GANTT图表，例如
______________________________
| p1 | p2 | p3 |
|_____________|_________|____|
0 12 18 27
答案 0 :(得分：1)
这些是我在C中实现的一些抢占式和非抢占式调度算法，它们肯定对您有用。
这些算法包含用于绘制甘特图和计算过程序列的单独C函数。
void drawGanttChart()
{
const int maxWidth=100;
int scalingFactor,i,counter,tempi,currentTime;
printf("The gantt chart for the given processes is : \n\n");
scalingFactor=maxWidth/totalCPUBurstTime;
for(i=0;i<scalingFactor*totalCPUBurstTime+2+numberOfProcesses;i++)
{
printf("-");
}
printf("\n|");
counter=0,tempi=0;
for(i=0;i<scalingFactor*totalCPUBurstTime;i++)
{
if(i==CPUBurstTime[counter]*scalingFactor+tempi)
{
counter++;
tempi=i;
printf("|");
}
else if(i==(CPUBurstTime[counter]*scalingFactor)/2+tempi)
{
printf("P%d",processNumber[counter]);
}
else
{
printf(" ");
}
}
printf("|");
printf("\n");
for(i=0;i<scalingFactor*totalCPUBurstTime+2+numberOfProcesses;i++)
{
printf("-");
}
printf("\n");
/* printing the time labels of the gantt chart */
counter=0;
tempi=0;
currentTime=minimumArrivalTime;
printf("%d",currentTime);
for(i=0;i<scalingFactor*totalCPUBurstTime;i++)
{
if(i==CPUBurstTime[counter]*scalingFactor+tempi)
{
tempi=i;
currentTime+=CPUBurstTime[counter];
averageWaitingTime+=currentTime;
counter++;
printf("%2d",currentTime);
}
else
{
printf(" ");
}
}
currentTime+=CPUBurstTime[counter];
printf("%2d\n\n",currentTime);
averageWaitingTime=averageWaitingTime/numberOfProcesses;
printf("Average waiting Time : %f\n",averageWaitingTime);
}