可变分区调度算法有:最先适应分配算法,最优适应分配算法,最坏适应算法用户提出内存空间的申请；系统根据申请者的要求，按照一定的分配策略分析内存空间的使用情况，找出能满足请求的空闲区，分给申请者；当程序执行完毕或主动归还内存资源时，系统要收回它所占用的内存空间或它归还的部分内存空间。
1．程序运行时首先接收输入：空闲区数据文件，包括若干行，每行有两个数据项：起始地址、长度（均为整数），各数据项以逗号隔开。 2．建立空闲区表并在屏幕上显示输出空闲区表内容，空闲区表中记录了内存中可供分配的空闲区的始址和长度，用标志位指出该分区是否是未分配的空闲区。 3．从用户界面根据用户提示接收一个内存申请，格式为：作业名、申请空间的大小。 4．按照最差（最坏）适配算法选择一个空闲区，分割并分配，修改相应的数据结构（空闲区表），填写内存已分配区表（起始地址、长度、标志位），其中标志位的一个作用是指出该区域分配给哪个作业。 5．重复3、4，直到输入为特殊字符（0）。 6．在屏幕上显示输出新的空闲区表和已分配区表的内容。 本程序包括:FIFO,最优适应分配算法,最坏适应算法
可变分区存储管理 #include < stdio.h > #include < iostream.h > #include < string .h > #include < iomanip.h > const int MAXJOB = 100 ; // 定义表最大记录数 typedef struct node{ int start; int length; char tag[ 20 ]; }job; job frees[MAXJOB]; // 定义空闲区表 int free_quantity; job occupys[MAXJOB]; // 定义已分配区表 int occupy_quantity; // 初始化函数 void initial() { int i; for (i = 0 ;i < MAXJOB;i ++ ){ frees[i].start =- 1 ; frees[i].length = 0 ; strcpy(frees[i].tag, " free " ); occupys[i].start =- 1 ; occupys[i].length = 0 ; strcpy(occupys[i].tag, "" ); } free_quantity = 0 ; occupy_quantity = 0 ; } // 读数据函数 int readData() { FILE * fp; char fname[ 20 ]; cout << " 请输入初始空闲表文件名: " ; cin >> fname; if ((fp = fopen(fname, " r " )) == NULL){ cout << " 错误,文件打不开,请检查文件名 " << endl; } else { while ( ! feof(fp)){ fscanf(fp, " %d,%d " , & frees[free_quantity].start, & frees[free_quantity].length); free_quantity ++ ; } return 1 ; } return 0 ; } // sort void sort() { int i,j,p; for (i = 0 ;i < free_quantity - 1 ;i ++ ){ p = i; for (j = i + 1 ;j < free_quantity;j ++ ){ if (frees[j].start < frees[p].start){ p = j; } } if (p != i){ frees[free_quantity] = frees[i]; frees[i] = frees[p]; frees[p] = frees[free_quantity]; } } } // 显示函数 void view() { int i; cout << endl << " ---------------------------------------------------------- " << endl; cout << " 当前空闲表: " << endl; cout << " 起始地址 长度 状态 " << endl; for (i = 0 ;i < free_quantity;i ++ ){ cout.setf( 2 ); cout.width( 12 ); cout << frees[i].start; cout.width( 10 ); cout << frees[i].length; cout.width( 8 ); cout << frees[i].tag << endl; } cout << endl << " ---------------------------------------------------------- " << endl; cout << " 当前已分配表: " << endl; cout << " 起始地址 长度 占用作业名 " << endl; for (i = 0 ;i < occupy_quantity;i ++ ){ cout.setf( 2 ); cout.width( 12 ); cout << occupys[i].start; cout.width( 10 ); cout << occupys[i].length; cout.width( 8 ); cout << occupys[i].tag << endl; } } // 最先适应分配算法 void earliest() { char job_name[ 20 ]; int job_length; int i,j,flag,t; cout << " 请输入新申请内存空间的作业名和空间大小: " ; cin >> job_name; cin >> job_length; flag = 0 ; for (i = 0 ;i < free_quantity;i ++ ){ if (frees[i].length >= job_length){ flag = 1 ; } } if (flag == 0 ){ cout << endl << " Sorry,当前没有能满足你申请长度的空闲内存,请稍候再试 " << endl; } else { t = 0 ; i = 0 ; while (t == 0 ){ if (frees[i].length >= job_length){ t = 1 ; } i ++ ; } i -- ; occupys[occupy_quantity].start = frees[i].start; strcpy(occupys[occupy_quantity].tag,job_name); occupys[occupy_quantity].length = job_length; occupy_quantity ++ ; if (frees[i].length > job_length){ frees[i].start += job_length; frees[i].length -= job_length; } else { for (j = i;j < free_quantity - 1 ;j ++ ){ frees[j] = frees[j + 1 ]; } free_quantity -- ; cout << " 内存空间成功:} " << endl; } } } // 最优适应分配算法 void excellent() { char job_name[ 20 ]; int job_length; int i,j,flag,t; cout << " 请输入新申请内存空间的作业名和空间大小: " ; cin >> job_name; cin >> job_length; flag = 0 ; for (i = 0 ;i < free_quantity;i ++ ){ if (frees[i].length >= job_length){ flag = 1 ; } } if (flag == 0 ){ cout << endl << " Sorry,当前没有能满足你申请长度的空闲内存,请稍候再试 " << endl; } else { t = 0 ; i = 0 ; while (t == 0 ){ if (frees[i].length >= job_length){ t = 1 ; } i ++ ; } i -- ; for (j = 0 ;j < free_quantity;j ++ ){ if ((frees[j].length >= job_length) && (frees[j].length < frees[i].length)){ i = j; } } occupys[occupy_quantity].start = frees[i].start; strcpy(occupys[occupy_quantity].tag,job_name); occupys[occupy_quantity].length = job_length; occupy_quantity ++ ; if (frees[i].length > job_length){ frees[i].start += job_length; frees[i].length -= job_length; } else { for (j = i;j < free_quantity - 1 ;j ++ ){ frees[j] = frees[j + 1 ]; } free_quantity -- ; cout << " 内存空间成功:) " << endl; } } } // 最坏适应算法 void worst() { char job_name[ 20 ]; int job_length; int i,j,flag,t; cout << " 请输入新申请内存空间的作业名和空间大小: " ; cin >> job_name; cin >> job_length; flag = 0 ; for (i = 0 ;i < free_quantity;i ++ ){ if (frees[i].length >= job_length){ flag = 1 ; } } if (flag == 0 ){ cout << endl << " Sorry,当前没有能满足你申请长度的空闲内存,请稍候再试 " << endl; } else { t = 0 ; i = 0 ; while (t == 0 ){ if (frees[i].length >= job_length){ t = 1 ; } i ++ ; } i -- ; for (j = 0 ;j < free_quantity;j ++ ){ if ((frees[j].length >= job_length) && (frees[j].length > frees[i].length)){ i = j; } } occupys[occupy_quantity].start = frees[i].start; strcpy(occupys[occupy_quantity].tag,job_name); occupys[occupy_quantity].length = job_length; occupy_quantity ++ ; if (frees[i].length > job_length){ frees[i].start += job_length; frees[i].length -= job_length; } else { for (j = i;j < free_quantity - 1 ;j ++ ){ frees[j] = frees[j + 1 ]; } free_quantity -- ; cout << " 内存空间成功:) " << endl; } } } // 撤消作业 void finished() { char job_name[ 20 ]; int i,j,flag,p = 0 ; int start; int length; cout << " 请输入要撤消的作业名: " ; cin >> job_name; flag =- 1 ; for (i = 0 ;i < occupy_quantity;i ++ ){ if ( ! strcmp(occupys[i].tag,job_name)){ flag = i; start = occupys[i].start; length = occupys[i].length; } } if (flag ==- 1 ){ cout << " 没有这个作业名 " << endl; } else { // 加入空闲表 for (i = 0 ;i < free_quantity;i ++ ){ if ((frees[i].start + frees[i].length) == start){ if (((i + 1 ) < free_quantity) && (frees[i + 1 ].start == start + length)){ frees[i].length = frees[i].length + frees[i + 1 ].length + length; for (j = i + 1 ;j < free_quantity;j ++ ){ frees[j] = frees[j + 1 ]; } free_quantity -- ; p = 1 ; } else { frees[i].length += length; p = 1 ; } } if (frees[i].start == (start + length)){ frees[i].start = start; frees[i].length += length; p = 1 ; } } if (p == 0 ){ frees[free_quantity].start = start; frees[free_quantity].length = length; free_quantity ++ ; } // 删除分配表中的该作业 for (i = flag;i < occupy_quantity;i ++ ){ occupys[i] = occupys[i + 1 ]; } occupy_quantity -- ; } } // 显示版权信息函数 void version() { cout << endl << endl; cout << " ┏━━━━━━━━━━━━━━━━━━━━━━━┓ " << endl; cout << " ┃ 可变分区存储管理模拟系统 ┃ " << endl; cout << " ┠───────────────────────┨ " << endl; cout << " ┃ (c)All Right Reserved Neo ┃ " << endl; cout << " ┃ sony006@163.com ┃ " << endl; cout << " ┃ version 2004 build 1122 ┃ " << endl; cout << " ┗━━━━━━━━━━━━━━━━━━━━━━━┛ " << endl; cout << endl << endl; } void main() { int flag = 0 ; int t = 1 ; int chioce = 0 ; version(); initial(); flag = readData(); while (flag == 1 ){ sort(); cout << endl << endl << " ========================================================= " << endl; cout << " 可变分区存储管理模拟系统 " << endl; cout << " ========================================================= " << endl; cout << " 1.申请空间 2.撤消作业 3.显示空闲表和分配表 0.退出 " << endl; cout << " 请选择: " ; cin >> chioce; switch (chioce){ case 1 : // 换算法请换下一句调用 earliest(); break ; case 2 : finished(); break ; case 3 : view(); break ; case 0 : flag = 0 ; break ; default : cout << " 选择错误! " << endl; } } }