为什么80%的码农都做不了架构师？>>> 
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 << " ┃ [email protected] ┃ " << 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;
}
}
}