Question

Please solve in python and provide comments explaining your codes. Your output must be the same as the example and result given below in the images.

This task is to write a very basic text editor. It allows you to add, delete and modify lines of text.  Use a list of strings to store the lines, with each list element being one line. The elements of the list are modified according the commands given by the user.

The editor repeatedly:
1.    displays the lines entered so far prefixed with a line number in front of each and ending with an empty line.
2.    it waits for the user to enter a command
3.    if it's a valid command, it modifies the list appropriately
4.    go back to step #1

Initially, the list of lines will be empty.

You should have a function for each of the commands below, except for Quit.

The valid commands are:

• a - add a line
  Lines from the user are added to the lines collected so far. All lines entered are added to the list until the user enters a line containing a single #.
• d - delete a line
  Prompt for a line number and then delete that line. Use the Python command del to delete a line from the list of lines. Check that the line number entered is valid. If it is invalid, ask for a line number again.
• r - replace a line
  Prompt for a line number and then replace that line with a new one from the user. Check that the line number entered is valid. If it is invalid, ask for a line number again.
• f - find and replace a string
  Prompt for one string (the search pattern) and then a second (the replacement). Replace all occurrences of the first string with the second, using string.replace() .
• p – copy/paste lines
  Prompt for two line numbers, one is the starting line of text to copy, and the second is the end line of the text to copy. Slice this part of the list, and add it to the end of the list as a single string.
  Check that the line numbers entered are valid. If they are invalid, ask for a line numbers again.
• c - Clear all
  Delete all lines, so the state is like when the program starts.
• q - Quit
  End the program.

***Clarification on line numbers*** You can expect that any line numbers entered for the above functions are integers. You do NOT need to test if they are non-integer inputs, but just that they are in range of the line numbers that exist.

Here's an example of this editor in use. Several commands are shown. Initially, before the 'a' (add) command is used, there aren't any lines, so nothing is output before the command prompt.

Command a, d, r, f, p, c, q: a
Add a line: It is a lovely morning
Add a line: for a walk.
Add a line: It is a lovely evening
Add a line: for reading a book
Add a line: in front of the fire.
Add a line: #
1: It is a lovely morning
2: for a walk.
3: It is a lovely evening
4: for reading a book
5: in front of the fire.

Command a, d, r, f, p, c, q: d
Line number: 5
1: It is a lovely morning
2: for a walk.
3: It is a lovely evening
4: for reading a book

Command a, d, r, f, p, c, q: r
Replace line number: 2
Replacement string: for a walk in the park.
1: It is a lovely morning
2: for a walk in the park.
3: It is a lovely evening
4: for reading a book

Command a, d, r, f, p, c, q: f
Find string: lovely
Replace with: wonderful
1: It is a wonderful morning
2: for a walk in the park.
3: It is a wonderful evening
4: for reading a book

Command a, d, r, f, p, c, q: p
Start line number: 7
End line number: 8
Start line number: 1
End line number: 2
1: It is a wonderful morning
2: for a walk in the park.
3: It is a wonderful evening
4: for reading a book
5: It is a wonderful morning for a walk in the park.

Command a, d, r, f, p, c, q: c

Command a, d, r, f, p, c, q: q

For example: Input Result a It is a lovely morning for a walk. It is a lovely evening for reading a book in front of the fire. Command a, d, r, f, P, C, q: a Add a line: It is a lovely morning Add a line: for a walk. Add a line: It is a lovely evening Add a line: for reading a book Add a line: in front of the fire. Add a line: # 1: It is a lovely morning 2: for a walk. 3: It is a lovely evening 4: for reading a book 5: in front of the fire. # d 5 r 2 for a walk in the park. f lovely wonderful P 7 8 1 Command a, d, r, f, P, C, 4:d Line number: 5 1: It is a lovely morning 2: for a walk. 3: It is a lovely evening 4: for reading a book 2 с Command a, d, r, f, P, C, q: Replace line number: 2 Replacement string: for a walk in the park. 1: It is a lovely morning 2: for a walk in the park. 3: It is a lovely evening 4: for reading a book Command a, d,r, f, P, C, q: f Find string: lovely Replace with: wonderful 1: It is a wonderful morning 2: for a walk in the park. 3: It is a wonderful evening 4: for reading a book

Answer 1

Answer:

CODE:

# list to store the lines
lines = []

# function to add lines
def add_lines():

    # infinite looping
    while True:

        # getting input from the user
        line=input('Add a line: ')

        # break when input is #
        if line == '#':
            break
        else:

            # adding line to the list
            lines.append(line)

# function to delete a line
def delete_line():

    # infite looping
    while True:

        # getting line number
        num = int (input('Line number: '))

        # checking for valid line number
        if num >=1 and num <=len(lines):

            # deleting the line
            del lines[num-1]
            break
        else:
            print('Invalid line number. Try again.')

# function to replace line with another line
def replace_line():

    # infite looping
    while True:

        # replacement line number input
        replace = int(input('Replace line number: '))

        # checking for valid line number
        if replace >=1 and replace <=len(lines):

            # getting replacement string
            replacement = input('Replacement string: ')

            # deleting the line
            del lines[replace-1]

            # inserting the line
            lines.insert(replace-1,replacement)
            break
    
        else:
            print('Invalid line number. Try again.')

# function to find and replace string
def find_replace():

    # getting user input
    find = input('Find string: ')
    replace = input('Replace with: ')

    # looping through lines
    for num in range(len(lines)):

        # replacing the string
        lines[num]=lines[num].replace(find,replace)

# function to copy and paste
def copy_paste():

    # infite looping
    while True:

        # getting line numbers
        start=int(input('Start line number: '))

        end = int(input('End line number: '))

        # variable to store string
        s=''

        # checking for valid line number
        if start >=1 and start <=len(lines) and start< end and end >=1 and end <=len(lines):

            # getting string from list
            for line in lines[start-1:end]:            
                s+=line+' '

            # adding the line to end of the list
            lines.append(s)
            break

# function to clear the list
def clear_all():

    lines.clear()
    print('\n')

# infite looping
while True:

    # printing the lines from the list if not empty
    if lines:

        num = 0

        for i in lines:
            num +=1
            print('%d: %s' % (num,i))
        print('\n')

    # getting user choice
    choice = input('Command a, d, r, f, p, c, q: ')

    # calling the functions based on the choice of the user
    if choice == 'a':

        add_lines()

    elif choice == 'd':

        delete_line()

    elif choice == 'r':
        replace_line()

    elif choice == 'f':

        find_replace()

    elif choice == 'p':
        copy_paste()

    elif choice == 'c':
        clear_all()

    elif choice == 'q':
        break

    else:
        print('Enter a valid choice')

SCREENSHOT OF THE CODE:

1 2 # list to store the lines lines = [] 3 4 # function to add lines 5def add_lines(): 6 7 # infinite looping 8 v while True: 9 10 # getting input from the user 11 line=input('Add a line: ') 12 13 # break when input is # 14 if line == '#': 15 break 16 v else: 17 18 # adding line to the list 19 lines.append(line) 20 21 # function to delete a line 22 def delete_line(): 23 24 # infite looping 25 while True: 26 27 # getting line number 28 num = int (input('Line number: ')) 29 30 # checking for valid line number 31 v if num >=1 and num <=Len(lines): 32 33 # deleting the line 34 del lines [num-1] 35 break

else: print("Invalid line number. Try again.") # function to replace line with another line def replace_line(): # infite looping while True: # replacement line number input replace = int(input('Replace line number: ')) 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 # checking for valid line number if replace >=1 and replace <=Len(lines): # getting replacement string replacement = input('Replacement string: ') # deleting the line del lines[replace-1] # inserting the line lines.insert(replace-1, replacement) break else: print("Invalid line number. Try again.')

# function to find and replace string def find_replace(): # getting user input find = input('Find string: ') replace = input('Replacement string: ) # looping through lines for num in range(Len(lines )): # replacing the string lines [num]=lines [num].replace(find, replace) # function to copy and paste def copy paste(): 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 # infite looping while True: # getting line numbers start=int(input('Start line number: ')) end = int(input('End line number: ')) # variable to store string # checking for valid line number if start >=1 and start <=Len(lines) and start< end and end >=1 and end <=Len(lines): # getting string from list for line in lines [start-1:end] : s+-line+'

# adding the line to end of the list lines.append(s) break # function to clear the list def clear_all(): lines.clear() print('\n') # infite looping while True: # printing the lines from the list if not empty if lines: num = 0 98 99 100 101 102 103 104 105 106 107 198 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 for i in lines: num +=1 print("%d: %s % (num, i)) print('\n') # getting user choice choice = input('Command a, d, r, f, P, C, q: ') # calling the functions based on the choice of the user if choice == 'a': add_lines() elif choice == 'd': delete_line()

elif choice == 'r': replace_line() elif choice == 'f': find_replace() 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 elif choice == 'p': copy_paste() elif choice == 'C' clear_all() elif choice == 'q': break else: print("Enter a valid choice')

OUTPUT:

input Command a, d, r, f, P, C, q: a Add a line: It is a lovely morning Add a line: for a walk. Add a line: It is a lovely evening Add a line: for reading a book Add a line: in front of the fire. Add a line: # 1: It is a lovely morning 2: for a walk. 3: It is a lovely evening 4: for reading a book 5: in front of the fire. Command a, d, f, f, , c, q: d Line number: 5 1: It is a lovely morning 2: for a walk. 3: It is a lovely evening 4: for reading a book

Command a, d, r, f, p, c, q: r Replace line number: 2 Replacement string: for a walk in the park. 1: It is a lovely morning 2: for a walk in the park. 3: It is a lovely evening 4: for reading a book Command a, d, r, f, P. c, q: f Find string: lovely Replace with: wonderful 1: It is a wonderful morning 2: for a walk in the park. 3: It is a wonderful evening 4: for reading a book

Command a, d, r, f, P, c, q: p Start line number: 7 End line number: 8 Start line number: 1 End line number: 2 1: It is a wonderful morning 2: for a walk in the park. 3: It is a wonderful evening 4: for reading a book 5: It is a wonderful morning for a walk in the park. Command a, d, r, f, P, C, q: c Command a, d, r, f, pc, q: q ... Program finished with exit code 0 Press ENTER to exit console.

I have done it by using Python 3.

Thank you.