6/recent/ticker-posts

# Optimal Page Replacement 2

## Optimal is the simplest technique for replacing pages in a frame. It decides when a page fault occurs then which frames are to be replaced.  Create a program to counts the number of page fault occurs when an input reference string is given.  The input contains integer values for a number of pages in a queue, sequence of reference strings and frame size. The output should display the total number of page faults.

Note: Text in Bold corresponds to the input
Sample Input and Output :

Enter number of pages:
6
Enter reference string:
1
2
2
3
4
5

Enter number of frames:
3

Total Page Fault is 5

```#include<stdio.h>
int main()
{
int pages,m,n,frames,pagef=0,flag,temp,position,m_interval,p_frame=-1,interval[25],found;
printf("Enter number of pages: \n");
scanf("%d",&pages);
int page[pages];
printf("Enter reference string: \n");
for(m=0;m<pages;m++){
scanf("%d",&page[m]);
}
printf("Enter number of frames:\n");
scanf("%d",&frames);
int frame[frames];
for(m=0;m<frames;m++){
frame[m]=-1;
}
for(m=0;m<pages;m++)
{
flag=0;
for(n=0;n<frames;n++){
if(frame[n]==page[m]){
flag=1;
break;
}
}
if(flag==0){
if(p_frame==frames-1){
for(n=0;n<frames;n++){
for(temp=m+1;temp<pages;temp++){
interval[n]=0;
if(frame[n]==page[temp]){
interval[n]=temp-m;
break;
}
}
}
found=0;
for(n=0;n<frames;n++){
if(interval[n]==0){
position=n;
found=1;
break;
}
}
}
else{
position=++p_frame;
found=1;
}
if(found==0){
m_interval=interval[0];
position=0;
for(n=1;n<frames;n++){
if(m_interval<interval[n]){
m_interval=interval[n];
position=n;
}
}
}
frame[position]=page[m];
pagef++;
}
}
printf("Total Page Fault is %d\n",pagef);
}```