OS Page Replacement Algorithm Least Reccently used

Program Name	Write C Program for Operating system Page Replacement Algorithm Least Recently used
Theory	Least recently used pages are replaced in the memory.
Program	#include<stdio.h> int frames[3]; void main() { void display(); int p[12]={2,3,2,1,5,2,4,5,3,2,5,2},i,j,framessize[3]; int index,k,l,flag1=0,flag2=0,pf=0,framesize=3; printf("Page Replacement Algorithm - LEAST RECENTLY USED\n "); for(i=0;i<3;i++) frames[i]=-1; for(j=0;j<12;j++) { flag1=0,flag2=0; for(i=0;i<3;i++) { if(frames[i]==p[j]) { flag1=1; flag2=1; break; } } if(flag1==0) { for(i=0;i<3;i++) { if(frames[i]==-1) { frames[i]=p[j]; flag2=1; break; } } } if(flag2==0) { for(i=0;i<3;i++) framessize[i]=0; for(k=j-1,l=1;l<=framesize-1;l++,k--) { for(i=0;i<3;i++) { if(frames[i]==p[k]) framessize[i]=1; }} for(i=0;i<3;i++) { if(framessize[i]==0) index=i; } frames[index]=p[j]; pf++; } display(); } printf("\n Number of page faults :%d",pf+framesize); } void display() { int i; printf("\n"); for(i=0;i<3;i++) printf("\t%d",frames[i]); }
Input	p[12]={2,3,2,1,5,2,4,5,3,2,5,2}
Output	Page Replacement Algorithm - LEAST RECENTLY USED 2 -1 -1 2 3 -1 2 3 -1 2 3 1 2 5 1 2 5 1 2 5 4 2 5 4 3 5 4 3 5 2 3 5 2 3 5 2 Number of page faults :7

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