我正在练习如何通过重载运算符 new 来实现最佳拟合算法。
#include<iostream>
#include<malloc.h>
using namespace std;
#define SUCCESS 0
#define FAILURE -1
#define MAX_PARTITION_SIZE 1000
int *avail_space,*needed_space,*used_space,*done_space,*free_space;
int index,j,k,partitions,nop,flag,total_avail;
int *ptr[10];
int no_obj;
class memory{
private:
public:
void set_data();
void create_mem();
int create_partitions();
int alloc_space();
int showdata();
int bestfit_search(int* index);
void* operator new(size_t size);
void operator delete(void* p);
};
void* memory :: operator new(size_t size){
void* p;
int index_no;
memory obj;
int i = 0;
cout << "In Overloaded new" << endl;
cout << "Size : - " << size << endl;
for(i = 0; i < no_obj; i++){
cout << "address :" << ptr[i] << endl;
}
cout << "Size : " << sizeof(memory) << endl;
needed_space[index] = sizeof(memory);
obj.bestfit_search(&index_no); // I guess the problem is in this function where I need to call a non-static member function.
cout << "Index_no - " << index_no << endl;
return ptr[index_no];
}
void memory :: operator delete(void* p){
cout << "In Overloaded delete" << endl;
free(p);
}
void memory :: set_data(){
total_avail = MAX_PARTITION_SIZE;
index = partitions = nop = flag = j = k = 0;
}
void memory :: create_mem(){
memory* obj[10];
int index;
cout << "Enter the no of objects : " << endl;
cin >> no_obj;
for(index = 0; index < no_obj; index++){
cout << "Creating obj : - " << index << endl;
obj[index] = new memory();
}
}
/* Allocate memory to all the pointer variables based on the no of partitions */
int memory :: alloc_space(){
avail_space = new int[partitions];
needed_space = new int[partitions];
used_space = new int[partitions];
done_space = new int[partitions];
free_space = new int[partitions];
if((NULL == avail_space) || (NULL == needed_space) || (NULL == used_space) || (NULL == done_space) || (NULL == free_space)){
return FAILURE;
}
return SUCCESS;
}
/* Get the no of partitions and the space needed for each of the partition */
int memory :: create_partitions(){
cout << "Enter the No of partitions to be created : " << endl;
cin >> partitions;
cout << endl;
/* allocate the space for the pointers */
if(FAILURE == alloc_space()){
return FAILURE;
}
/* Get the size of each partition and update the freespace*/
cout << "Enter the space for each of the partitions : " << endl;
for(index = 0; index < partitions; index++){
cout << "Partition : " << index << "\t";
cin >> avail_space[index];
free_space[index] = avail_space[index];
ptr[index] =(int*)malloc(avail_space[index]);
if(ptr[index] == NULL){
cout << "Memory allocation failed!" << endl;
return FAILURE;
}
cout << "ptr : [" << index << "] - " << ptr[index] << endl;
}
cout << endl;
return SUCCESS;
}
/* Display the available, used and free space*/
int memory :: showdata(){
cout << "Available space "<< "Used space "<<"Free space " <<"Done space "<<endl;
for(index = 0; index < partitions; index++){
cout << avail_space[index]<<"\t\t"<<used_space[index]<<"\t\t"<<free_space[index]<<"\t\t"<<done_space[index]<<endl;
}
return SUCCESS;
}
/* Algorithm to search for the best fit memory */
int memory :: bestfit_search(int* index_no){
if(NULL == index_no){
cout << "Invalid parameter!" << endl;
return FAILURE;
}
int space = 0;
for(index = 0; index < nop; index++){
space = needed_space[index];
flag = 0;
for(k = space; k < MAX_PARTITION_SIZE; k++){ // MAX_PARTITION_SIZE - 1000
for(j = 0; j < partitions; j++){
if((space == avail_space[j]) && (done_space[j] != 1) && (flag != 1)){
used_space[j] = needed_space[index];
free_space[j] = avail_space[j] - needed_space[index];
done_space[j] = 1;
cout << "Used space" <<used_space[j] << " freespace" << free_space[index] <<"done space " << done_space[index] <<endl;
flag = 1;
*index_no = j;
break;
}
}
if(flag == 1){
break;
}
space++;
}
}
showdata();
return SUCCESS;
}
/* Main */
int main(){
memory obj;
obj.set_data();
obj.create_partitions();
obj.create_mem();
return SUCCESS;
}
程序运行：
Enter the No of partitions to be created :
5
Enter the space for each of the partitions :
Partition : 0 2
ptr : [0] - 0x9e62080
Partition : 1 7
ptr : [1] - 0x9e62090
Partition : 2 3
ptr : [2] - 0x9e620a0
Partition : 3 10
ptr : [3] - 0x9e620b0
Partition : 4 25
ptr : [4] - 0x9e620c0
Enter the no of objects :
2
Creating obj :
In Overloaded new
Size : 1
address :0x9e62080
address :0x9e62090
Size : 1
Available space Used space Free space Done space
2 0 2 0
7 0 7 0
3 0 3 0
10 0 10 0
25 0 25 0
Index_no - 0
Creating obj :
In Overloaded new
Size : 1
address :0x9e62080
address :0x9e62090
Size : 1
Available space Used space Free space Done space
2 0 2 0
7 0 7 0
3 0 3 0
10 0 10 0
25 0 25 0
Index_no - 1
我得到了错误的输出，因为可用空间 2 和 3 必须被已用空间占用为 1。