请写一段完整的，有FCFS,SSTF,SCAN,CSCAN算法的磁盘调度程序

好的，以下是一段完整的磁盘调度程序，包括FCFS、SSTF、SCAN和CSCAN算法：

#include<stdio.h>
#include<math.h>
#include<stdlib.h>

void fcfs(int n, int head, int req[])
{
    int seek_time = 0;
    printf("\n FCFS Disk Scheduling Algorithm\n");
    printf("Seek Sequence is:\n");
    for(int i=0; i<n; i++)
    {
        seek_time += abs(head - req[i]);
        head = req[i];
        printf("%d ", head);
    }
    printf("\nTotal Seek Time: %d\n", seek_time);
    printf("Average Seek Time: %f\n", (float)seek_time/n);
}

void sstf(int n, int head, int req[])
{
    int seek_time = 0;
    int completed[n];
    for(int i=0; i<n; i++)
    {
        completed[i] = 0;
    }
    printf("\n SSTF Disk Scheduling Algorithm\n");
    printf("Seek Sequence is:\n");
    for(int i=0; i<n; i++)
    {
        int min_dist = INT_MAX;
        int min_index = 0;
        for(int j=0; j<n; j++)
        {
            if(completed[j] == 0)
            {
                int dist = abs(head - req[j]);
                if(dist < min_dist)
                {
                    min_dist = dist;
                    min_index = j;
                }
            }
        }
        completed[min_index] = 1;
        seek_time += min_dist;
        head = req[min_index];
        printf("%d ", head);
    }
    printf("\nTotal Seek Time: %d\n", seek_time);
    printf("Average Seek Time: %f\n", (float)seek_time/n);
}

void scan(int n, int head, int req[], int max)
{
    int seek_time = 0;
    printf("\n SCAN Disk Scheduling Algorithm\n");
    printf("Seek Sequence is:\n");
    int direction = 1;
    int index;
    for(int i=0; i<n; i++)
    {
        if(direction == 1)
        {
            index = -1;
            int min_dist = INT_MAX;
            for(int j=0; j<n; j++)
            {
                if(req[j] >= head && abs(head - req[j]) < min_dist)
                {
                    min_dist = abs(head - req[j]);
                    index = j;
                }
            }
            if(index == -1)
            {
                direction = -1;
                printf("%d ", max-1);
                continue;
            }
        }
        else if(direction == -1)
        {
            index = -1;
            int min_dist = INT_MAX;
            for(int j=0; j<n; j++)
            {
                if(req[j] <= head && abs(head - req[j]) < min_dist)
                {
                    min_dist = abs(head - req[j]);
                    index = j;
                }
            }
            if(index == -1)
            {
                direction = 1;
                printf("%d ", 0);
                continue;
            }
        }
        seek_time += abs(head - req[index]);
        head = req[index];
        printf("%d ", head);
    }
    printf("\nTotal Seek Time: %d\n", seek_time);
    printf("Average Seek Time: %f\n", (float)seek_time/n);
}

void cscan(int n, int head, int req[], int max)
{
    int seek_time = 0;
    printf("\n CSCAN Disk Scheduling Algorithm\n");
    printf("Seek Sequence is:\n");
    int direction = 1;
    int index;
    for(int i=0; i<n; i++)
    {
        if(direction == 1)
        {
            index = -1;
            int min_dist = INT_MAX;
            for(int j=0; j<n; j++)
            {
                if(req[j] >= head && abs(head - req[j]) < min_dist)
                {
                    min_dist = abs(head - req[j]);
                    index = j;
                }
            }
            if(index == -1)
            {
                direction = -1;
                printf("%d ", max-1);
                seek_time += abs(head - (max-1));
                head = 0;
                continue;
            }
        }
        else if(direction == -1)
        {
            index = -1;
            int min_dist = INT_MAX;
            for(int j=0; j<n; j++)
            {
                if(req[j] <= head && abs(head - req[j]) < min_dist)
                {
                    min_dist = abs(head - req[j]);
                    index = j;
                }
            }
            if(index == -1)
            {
                direction = 1;
                printf("%d ", 0);
                seek_time += abs(head - 0);
                head = max-1;
                continue;
            }
        }
        seek_time += abs(head - req[index]);
        head = req[index];
        printf("%d ", head);
    }
    printf("\nTotal Seek Time: %d\n", seek_time);
    printf("Average Seek Time: %f\n", (float)seek_time/n);
}

int main()
{
    int n, head, max;
    printf("Enter the number of requests: ");
    scanf("%d", &n);
    int req[n];
    printf("Enter the requests: ");
    for(int i=0; i<n; i++)
    {
        scanf("%d", &req[i]);
    }
    printf("Enter the initial head position: ");
    scanf("%d", &head);
    printf("Enter the maximum disk size: ");
    scanf("%d", &max);
    fcfs(n, head, req);
    sstf(n, head, req);
    scan(n, head, req, max);
    cscan(n, head, req, max);
    return 0;
}

该程序中，我们首先定义了四个函数，分别是FCFS、SSTF、SCAN和CSCAN算法的实现。然后在主函数中，我们先读取用户输入的请求和初始磁头位置，然后调用四个函数来执行不同的磁盘调度算法，并输出结果。

值得注意的是，该程序中使用了C语言的标准库函数，例如`abs()`和`INT_MAX`，需要包含相应的头文件。此外，SCAN和CSCAN算法需要知道磁盘的最大容量，因此我们在主函数中也要读取该值。

希望这段程序能够帮助你理解磁盘调度算法的实现过程。