Problem with C++ in linux
Uhm, i'm new to linux as well as C++ so i was supposed to change the if none are available part to a random replacement algorithm from the previous LRU algorithm but i can't get the program to run in linux RedHat 9.0, when i used the terminal to gcc my input file...something about not recognising the rand and srand..?? Plus i also can't output the hit/miss ratio for this code using scanf or cout, what gives??
Can anyone please help me?
Code:
#include <stdio.h>
#include <time.h>
#include <math.h>
#define MAXSWAP 500
#define MAXPAGE 20
typedef struct{
int age;
int state; /* 1 is used, 0 is unused */
char pageframe[5];
}vm;
int find_next_available_page(vm * memory, vm * swap)
{
int i,position;
int highest=0;
int j=-1;
/* see if there are any empty page frames in memory */
for(i=0;i<MAXPAGE;i++)
{
if(memory[i].state==0)
{
return i;
}
}
/* if none are available, a suitable candidate must be chosen... */
srand (time(NULL));
position = rand()%20; /* any position could be chosen to be replaced */
/* find an empty swap spot */
for(i=0;i<MAXSWAP;i++)
{
if(swap[i].state==0)
j=i;
}
if(j<0)
{
printf("Out of memory condition in simulation. Exiting\n");
exit(0);
}
strncpy(swap[j].pageframe, memory[position].pageframe, 5);
memory[position].state=0;
memory[position].age=0;
swap[j].state=1;
/* returns free spot */
return position;
}
int find_page_in_memory(char * page, vm * memory)
{
int i;
for(i=0;i<MAXPAGE;i++)
{
if(memory[i].state=1){
memory[i].age = memory[i].age+1;
}
}
for(i=0;i<MAXPAGE;i++)
{
if(strncmp(page, memory[i].pageframe, 5)==0){
memory[i].age = 0;
return 1;
}
}
return 0;
}
int find_page_in_swap(char * page, vm * swap, vm * memory)
{
int i,availablepage;
for(i=0;i<MAXSWAP;i++)
{
if(strncmp(page, swap[i].pageframe, 5)==0){
availablepage = find_next_available_page(memory, swap);
strncpy(memory[availablepage].pageframe, page, 5);
memory[availablepage].state=1;
memory[availablepage].age=0;
swap[i].state=0;
return 1;
}
}
return 0;
}
void dump_memory_map(vm *memory, vm *swap)
{
int i;
for (i=0;i<MAXPAGE;i++)
{
printf(" RAM Frame[%2i] = %s\n",i,memory[i].pageframe);
}
printf("\n");
for (i=0;i<MAXSWAP;i++)
{
printf("Swap Frame[%2i] = %s\n",i,swap[i].pageframe);
}
printf("\n");
}
int main(int argc, char *argv[])
{
FILE * fptr;
vm memory[MAXPAGE];
char page[5];
vm swap[MAXSWAP];
int i,hit,miss,availablepage;
hit = miss = 0;
int available_page = 0;
if(argc!=2){
fprintf(stderr, "Please specify trace file\n");
exit(1);
}
/* initialize all age as 0 and all state as unused */
for(i=0;i<MAXPAGE;i++)
{
memory[i].age=0;
memory[i].state=0;
memory[i].pageframe[0]='\0';
}
for(i=0;i<MAXSWAP;i++)
{
swap[i].age=0;
swap[i].state=0;
swap[i].pageframe[0]='\0';
}
fptr = fopen(argv[1], "r");
if(fptr==NULL){
fprintf(stderr, "Unable to open trace file");
exit(1);
}
while(!feof(fptr)){
fscanf(fptr,"%5s",page);
dump_memory_map(memory,swap); /* remove or comment this debugging line if
program output gets too verbose */
printf("Page Requested: %s\n",page);
if(!(find_page_in_memory(page,memory))){
miss++;
printf("Page miss!\n");
if(!(find_page_in_swap(page,swap,memory))){
availablepage = find_next_available_page(memory, swap);
strncpy(memory[availablepage].pageframe, page, 5);
memory[availablepage].state=1;
memory[availablepage].age=0;
}
}
else
{
hit++;
printf("Page hit!\n");
}
}
return 0;
}
Re: Problem with C++ in linux
Quote:
Originally posted by MelaOS
Uhm, i'm new to linux as well as C++ so i was supposed to change the if none are available part to a random replacement algorithm from the previous LRU algorithm but i can't get the program to run in linux RedHat 9.0, when i used the terminal to gcc my input file...something about not recognising the rand and srand..?? Plus i also can't output the hit/miss ratio for this code using scanf or cout, what gives??
Can anyone please help me?
Doing a man on any of these functions will tell you what header they are in. Googling "man rand" will bring up the man page for rand and this works for most any C function and alot of other things too. Scanf is not what you want for outputing the hit/miss ratio. 'man scanf' for details. Include iostream.h or iostream to get access to cout, and compile with g++ not gcc, unless you are passing the C++ language flag to gcc.
