Thread: 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;
}