Question

using matlab

Programming Assignment 5: For-Loops CSCI 251-Spring 2019 This program will use the concepts in the decimal to octal program Introduction: In file systems on servers (think of websites like Google, Amazon, etc.), permission to access the files come from the octal number system. Given an octal quadruple, permissions are defined for the user, the group, and other as follows: Permission First Digit Second Digit Third Digit Fourth Digit Always 01 (User-u) 0 」(Group-g) | (Other-o) Read (r) Write (w) 0 Execute (x) 0 Add the values in each column to determine the permission for the user/group/other. For example, 7, for the user gives read/write/execute permission (to get 7, you have 4+2+1 so read is given, write is given and execute is given). If user had 3 as a permission, instead, then only write/execute permissions are given (to get 3 you add 2+1 so only write is given and execute is given). If user had 6 as a permission, then 4+2 is required, which is read/write permissions. Program Details: Create a MATLAB script called octalFilePermissions.m. Prompt for a file permissions string of quadruples, outputting the file permission for user/group/other (see Sample Output). Algorithm Use a for-loop to read one permission quadruple at a time (i.e., use a stepping value of 4 in your for-loop). 1. Use a nested for-loop to step through each quadruple, determining this user's permissions: a. Create an output variable. Note that this is within the first for-loop because it needs to be reset to empty each time. Recall that a string is initialized as empty by assigning it the value [] Now, create a variable that will contain just the one quadruple. If your outer for-loop header uses i as the variable, then oneQuadruple permissions(i:(i+3)) will create a character string of the quadruple. This assumes that permissions is the name of your input variable. i. The colon in MATLAB will create a substring with i as the starting index and (i+3) as the ending index, in my example. When stepping through the quadruple, begin at 2 since the first character is a throw away for this program. Use 2 switch statements. The first will determine whose permission: user/eroup/other. The second will determine the type of permission: ili. iv. 0: none 1: execute 2: write 3: write/execute 4: read 5: read/execute 6: read/write 7: read/write/execute v. append to your output variable Now that one quadruple has been processed, output its value and a new line (see Sample Output) b. 2. Before each significant step, provide a comment explaining the step (do not comment every line of code). Sample Output Enter file permissions 07170502047701770361037607500675065305150020006502700336061303550625 User: read/write/execute Group: execute Other: read/write/execute User: read/execute Group: none Other: write User: read Group: read/write/execute Other: read/write/execute User: execute Group: read/write/execute Other: read/write/execute User: write/execute Group: read/write Other: execute User: write/execute Group: read/write/execute Other: read/write User: read/write/execute Group: read/execute Other: none User: read/write Group:read/write/execute Other:read/execute User: read/write Group: read/execute Other: write/execute User: read/execute Group: execute Other: read/execute User: none Group: write Other: none User: none Group: read/write Other: read/execute User: write Group: read/write/execute Other: none User: write/execute Group: write/execute Other: read/write User: read/write Group: execute Other: write/execute User: write/execute Group: read/execute Other: read/execute User: read/write Group: write Other: read/execute Include header comments (at the beginning of your m-file) formatted as shown below. Your electronic submission of the program file will represent your endorsement of the Honor Code Statement

Answer 1

Screenshot

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5205100280065 User res writefevecute Group execute Otheriresd writerexecute Useriresd Groupreadrite/execute otherireadite execuze User rite/execut Groupiread/write otheriexecute User reac nritefecute Sroupread execute 0chr:noe i-p-strcat(inp,charis) Loop uncii end of the strins Each tine new quadruple or -11+3 User resvexeeute Group:execute Otherires execute roup:rit vswitth for who usirc nutput strest(autput. Other: switach to get type of perni ssion

Program

%prompt string
inp='Enter file permissions:';
%for next line
inp=strcat(inp,char(13));
%Prompt
filePermission=input(inp,'s');
%Loop until end of the string
for i=1:i+4:length(filePermission)
   %Each time new quadruple
   quadruple='';
   %get quadruple
   for j=i:i+3
     quadruple=strcat(quadruple,filePermission(j));
   end
   %Output string
   output='';
   %Loop through quadruplt
   for n=2:length(quadruple)
     %Switch for who using
     switch n
       case 2
        output=strcat(output,'User:');
       case 3
        output=strcat(output,' Group:');
       case 4
        output=strcat(output,' Other:');
     end
     %Convert into int
     val=str2num(quadruple(n));
     %Swithch to get type of permission
     switch val
       case 0
        output=strcat(output,'none');
       case 1
        output=strcat(output,'execute');
       case 2
        output=strcat(output,'write');
      case 3
        output=strcat(output,'write/execute');
      case 4
       output=strcat(output,'read');
      case 5
        output=strcat(output,'read/execute');
      case 6
        output=strcat(output,'read/write');

    case 7
        output=strcat(output,'read/write/execute');
     end
   
   end
   %Display details
disp(output)

end

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Output

Enter file permissions:
071705020477017703610376075006750653051500200065
User:read/write/execute Group:execute Other:read/write/execute
User:read/execute Group:none Other:write
User:read Group:read/write/execute Other:read/write/execute
User:execute Group:read/write/execute Other:read/write/execute
User:write/execute Group:read/write Other:execute
User:write/execute Group:read/write/execute Other:read/write
User:read/write/execute Group:read/execute Other:none
User:read/write Group:read/write/execute Other:read/execute
User:read/write Group:read/execute Other:write/execute
User:read/execute Group:execute Other:read/execute
User:none Group:write Other:none
User:none Group:read/write Other:read/execute