Two Level Directory

 Two Level Directory :

As we have seen, a single level directory often leads to confusion of files names among different users. the solution to this problem is to create a separate directory for each user. 

In the two-level directory structure, each user has their own user files directory (UFD). The UFDs have similar structures, but each lists only the files of a single user. system’s master file directory (MFD) is searches whenever a new user id=s logged in. The MFD is indexed by username or account number, and each entry points to the UFD for that user.

Advantages: 

• We can give full path like /User-name/directory-name/.

• Different users can have the same directory as well as the file name.

• Searching of files becomes easier due to pathname and user-grouping.

Disadvantages:

• A user is not allowed to share files with other users.

• Still, it not very scalable, two files of the same type cannot be grouped together in the same user. 

Program :

#include<string.h>

#include<stdlib.h>

#include<stdio.h>

struct

{

char dname[10],fname[10][10];

int fcnt;

}dir[10];

void main()

{

int i,ch,dcnt,k;

char f[30], d[30];

dcnt=0;

while(1)

{

printf("\n\n1. Create Directory\t2. Create File\t3. Delete File");

printf("\n4. Search File\t\t5. Display\t6. Exit\tEnter your choice -- ");

scanf("%d",&ch);

switch(ch)

{

case 1: printf("\nEnter name of directory -- ");

scanf("%s", dir[dcnt].dname);

dir[dcnt].fcnt=0;

dcnt++;

printf("Directory created");

break;

case 2: printf("\nEnter name of the directory -- ");

scanf("%s",d);

for(i=0;i<dcnt;i++)

if(strcmp(d,dir[i].dname)==0)

{

printf("Enter name of the file -- ");

scanf("%s",dir[i].fname[dir[i].fcnt]);

printf("File created");

break;

}

if(i==dcnt)

printf("Directory %s not found",d);

break;

case 3: printf("\nEnter name of the directory -- ");

scanf("%s",d);

for(i=0;i<dcnt;i++)

{

if(strcmp(d,dir[i].dname)==0)

{

printf("Enter name of the file -- ");

scanf("%s",f);

for(k=0;k<dir[i].fcnt;k++)

{

if(strcmp(f, dir[i].fname[k])==0)

{

printf("File %s is deleted ",f);

dir[i].fcnt--;

strcpy(dir[i].fname[k],dir[i].fname[dir[i].fcnt]);

goto jmp;

}

}

printf("File %s not found",f);

goto jmp;

}

}

printf("Directory %s not found",d);

jmp : break;

case 4: printf("\nEnter name of the directory -- ");

scanf("%s",d);

for(i=0;i<dcnt;i++)

{

if(strcmp(d,dir[i].dname)==0)

{

printf("Enter the name of the file -- ");

scanf("%s",f);

for(k=0;k<dir[i].fcnt;k++)

{

if(strcmp(f, dir[i].fname[k])==0)

{

printf("File %s is found ",f);

goto jmp1;

}

}

printf("File %s not found",f);

goto jmp1;

}

}

printf("Directory %s not found",d);

jmp1: break;

case 5: if(dcnt==0)

printf("\nNo Directory's ");

else

{

printf("\nDirectory\tFiles");

for(i=0;i<dcnt;i++)

{

printf("\n%s\t\t",dir[i].dname);

for(k=0;k<dir[i].fcnt;k++)

printf("\t%s",dir[i].fname[k]);

}

}

break;

default:exit(0);

}

}

}

Output :

1. Create Directory     2. Create File  3. Delete File

4. Search File          5. Display      6. Exit Enter your choice -- 2

Enter name of the directory -- a

Directory a not found

1. Create Directory     2. Create File  3. Delete File

4. Search File          5. Display      6. Exit Enter your choice -- 1

Enter name of directory -- a

Directory created

1. Create Directory     2. Create File  3. Delete File

4. Search File          5. Display      6. Exit Enter your choice -- 2

Enter name of the directory -- a

Enter name of the file -- File

File created

1. Create Directory     2. Create File  3. Delete File

4. Search File          5. Display      6. Exit Enter your choice -- 6