4. Discuss the advantages and disadvantages of using the same system call interface for both files and devices. Why do you think operating system designers would use the same interface for both

Answer:

A. LCD power inverter

B. AC adapter

C. Battery

Answer:

Security controls are those measures taken to prevent, identify, counteract, and reduce security risks to computer systems, whereas, Security Requirements are guidelines or frameworks that stipulates measures to ensure security control.

Explanation:

Security controls encompass all the proactive measures taken to prevent a breach of the computer system by attackers. Security requirements are those security principles that need to be attained by a system before it can be certified as safe to use.

Security controls are of three types namely, management, operational, and technical controls. Examples of technical controls are firewalls and user authentication systems. A statement like 'The system shall apply load balancing', is a security requirement with an emphasis on availability.

Answer:

a. cd into the nested directories/ nested - level - 1 / directory using an absolute path

Explanation:

The directory is a location on the hard disk, which is also called a folder. It contains the files and also contains the other directories called sub directories.

A path to a file is merged with a slash and determines the file or directory in the operating system. An absolute path is the location file or directory from the actual file system

The directory's absolute path starts with a slash, and all slashed in the directory separates the directions.

All directions in the absolute path are written on the left side. The last name in the path may belong to the file, and the pwd command can determine the current directory.

The relative path is the location of the file. It begins with the working directory. An absolute path is unambiguous and working with deeply nested directories.

There are two commands which are used such as

We easily navigate the file system with the help of an absolute path.

Answer:

def random_marks(apostrophe, quotation, apostrophe_quotation):

   return "'"*apostrophe + "\""*quotation + "'\""*apostrophe_quotation

print(random_marks(3, 2, 3))

Explanation:

Create a function called random_marks that takes apostrophe, quotation, and apostrophe_quotation as parameters. Inside the function, return apostrophe sign times apostrophe plus quotation mark times quotation plus apostrophe sign quotation mark times apostrophe_quotation.

Note that plus sign (+) is used to concatenate strings. Also, if you multiply a string with a number, you get that number of strings ("#"*3 gives ###).

Then, call the function with given parameters and print

Answer:

Linked lists and arrays are both linear data structures but while an array is a collection of items that can be accessed randomly, a linked list can be accessed sequentially.

A sparse matrix contains very few non-zero elements. For example;

_                        _

|  0   0   3  0  6    |

|   0   5   0  0  4   |

|   2   0   0  0  0   |

|_ 0   0   0  0  0 _|

In the implementation of a sparse matrix, the following are some of the pros and cons of using a linked list over an array;

PROS

i.  Linked lists are dynamic in nature and are readily flexible - they can expand and contract without having to allocate and/or de-allocated memory compared to an array where an initial size might need to be set and controlled almost manually. This makes it easy to store and remove elements from the sparse matrix.

ii. No memory wastage. Since the size of a linked list can grow or shrink at run time, there's no memory wastage as it adjusts depending on the number of items it wants to store. This is in contrast with arrays where you might have unallocated slots. Also, because the zeros of the sparse matrix need not be stored when using linked lists, memory is greatly conserved.

CONS

i. One of the biggest cons of linked lists is the difficulty in traversing items. With arrays, this is just of an order of 0(1) since the only requirement is the index of the item. With linked lists, traversal is sequential which means slow access time.

ii. Storage is another bottle neck when using linked lists in sparse matrix implementation. Each node item in a linked list contains other information that needs to be stored alongside the value such as the pointer to the next or previous item.

Answer:

It uses a recursive method to find out if a string is a palindrome

Explanation:

Palindrome is a word or a sequence which is read same as backward as forwards. There are various method to find a palindrome. Palindrome can be determined recursively by identifying the first and last letters of the word. These first and last letter should be same. If they are same then the word or sequence is palindrome.

Answer:

Here is the C++ program for Employee class with fields id,name and sal.

#include <iostream>  // to use input output functions

#include <string>  //to manipulate and use strings

using namespace std;   // to access objects like cin cout

class Employee {  //class Employee

private:  

/* the following data members are declared as private which means they can only be accessed by the functions within Employee class */

  string name;  //name field

  int id; //id field

  double sal;   //salary field

public:    

  Employee();  // constructor that initializes an object when it is created

/* setName, setID and setSalary are the mutators which are the methods used to change data members. This means they set the values of a private fields i.e. name, id and sal */

  void setName(string n)  //mutator for name field

     { name = n; }        

  void setId(int i)  //mutator for id field

     { id = i; }        

  void setSalary(double d)  //mutator for sal field

     { sal = d; }  

/* getName, getID and getSalary are the accessors which are the methods used to read data members. This means they get or access the values of a private fields i.e. name, id and sal */

  string getName()  //accessor for name field

     { return name; }        

  int getId()  //accessor for id field

     { return id; }        

  double getSalary()  //accessor for sal field

     { return sal; }  };  

Employee::Employee() {  //default constructor where the fields are initialized

  name = "";  // name field initialized

  id = 0;  // id field initialized to 0

  sal = 0;   }   // sal field initialized to 0

void display(Employee);  

// prototype of the method display() to display the data of Employee

int main() {  //start of the main() function body

  Employee emp;  //creates an object emp of Employee class

/*set the name field to Abc Xyz which means set the value of Employee class name field to Abc Xyz  through setName() method and object emp */

  emp.setName("Abc Xyz");  

/*set the id field to 1234 which means set the value of Employee class id field to 1234  through setId() method and object emp */

  emp.setId(1234);

/*set the sal field to 1000 which means set the value of Employee class sal field to 1000  through setSalary() method and object emp */

  emp.setSalary(1000);    

  display(emp);  }   //calls display() method to display the Employee data

void display(Employee e) {  // this method displays the data in the Employee //class object passed as a parameter.

/*displays the name of the Employee . This name is read or accessed through accessor method getName() and object e of Employee class */

  cout << "Name: " << e.getName() << endl;  

/*displays the id of the Employee . This id is read or accessed by accessor method getId() and object e */

  cout << "ID: " << e.getId() << endl;

/*displays the salary of the Employee . This sal field is read or accessed by accessor method getSalary() and object e */

  cout << "Salary: " << e.getSalary() << endl;  }

Explanation:

The program is well explained in the comments mentioned with each statement of the program.

The program has a class Employee which has private data members id, name and sal, a simple default constructor Employee(), mutatator methods setName, setId and setSalary to set the fields, acccessor method getName, getId and getSalary to get the fields values.

A function display( ) is used to display the Employee data i.e. name id and salary of Employee.

main() has an object emp of Employee class in order to use data fields and access functions defined in Employee class.

The output of the program is:

Name: Abc Xyz                                                                                                      

ID: 1234                                                                                                                  

Salary: 1000

The program and its output are attached.