Concept: In the chained method file allocation table contains a field which points to starting block of memory. From it for each bloc a pointer is kept to next successive block. Hence, there is no external fragmentation
ALGORTHIM:
Step 1: Start
Step 2: Get the number of files.
Step 3: Get the memory requirement of each file.
Step 4: Allocate the required locations by selecting a location randomly q= random(100);
a) Check whether the selected location is free .
b) If the location is free allocate and set flag=1 to the allocated locations.
While allocating next location address to attach it to previous location
for(i=0;i<n;i++) {=”” for(j=”0;j<s[i];j++)” q=”random(100);” if(b[q].flag=”=0)” b[q].flag=”1;” b[q].fno=”j;” r[i][j]=”q;” if(j=””>0)
{
}
}
p=r[i][j-1];
b[p].next=q;
}
Step 5: Print the results file no, length ,Blocks allocated.
Step 6: Stop
#include<stdio.h>
main()
{
int f[50],p,i,j,k,a,st,len,n,c;
clrscr();
for(i=0;i<50;i++)
f[i]=0;
printf("Enter how many blocks that are already allocated");
scanf("%d",&p);
printf("\nEnter the blocks no.s that are already allocated");
for(i=0;i
{
scanf("%d",&a);
f[a]=1;
}
X:
printf("Enter the starting index block & length");
scanf("%d%d",&st,&len);
k=len;
for(j=st;j<(k+st);j++)
{
if(f[j]==0)
{
f[j]=1;
printf("\n%d->%d",j,f[j]);
}
else
{
printf("\n %d->file is already allocated",j);
k++;
}
}
printf("\n If u want to enter one more file? (yes-1/no-0)");
scanf("%d",&c);
if(c==1)
goto X;
else
exit();
getch( );
}
OUTPUT: Enter how many blocks that are already allocated 3 Enter the blocks no.s that are already allocated 4 7 9 Enter the starting index block & length 3 7 3->1 4->1 file is already allocated 5->1 6->1 7->1 file is already allocated 8->1 9->1file is already allocated 10->1 11->1 12->1