Question

PYTHON

4. While Loops (25%) You will be writing a "shell" application, it will be on a loop, taking in commands from the user. The command syntax is as follows command> <arga» <arg1> arg n> The commands you are to implement: Command Description Prints all arguments on the same line, with a space between each. Treats all arguments as floating-point numbers, and prints the average. MUST print an error if given invalid arguments Finds the index of arg1 in arg0. If there are not at least 2 args, print out an error Reads a text file containing 0 or more of commands, treating it exactly as if it was coming in from standard input. echo average strstr script Example run: (User input is prefixed by [IN]) (Output is prefixed by [OUT]) [IN] echo Hello, World! [OUT] Hello, borld! [IN] average ape [OUT] ERROR: usage: average <number <number> [IN] average 2 1 336 OUT] 3 [IN] strstr a [OUT] ERROR : usage : strstrarga» ?arg1> [IN] strstr pinecone cone OUT1 4 [IN] script introduction.script <number> And, if we have a file, introduction.script containing the following introduction.script echo This is my introduction!!! echo How cool is this? And our application output... [OUT] This is my introduction!!! [OUT] how cool is this?

Answer 1

**********************************************Code************************************

class ShellApplication:
    def __init__(self):
        # From here we are taking the data from user and based on the command given we are calling functions
        while True:
            print "----------------------------------"
            print "1-Command\n2-stop"
            ch = input()
            if ch == 1:
                print "Enter command:"
                command = raw_input().split(" ")
                print "*****************************"
                if command[0] == "echo":
                    # If first word is echo then we are calling display_text function
                    self.display_text(command)
                elif command[0] == "average":
                    # If first word is average then we are calling print_average function
                    self.print_average(command)
                elif command[0] == "strstr":
                    # If first word is strstr then we are calling find_index
                    self.find_index(command)
                elif command[0] == "script":
                    # If first word is  script then we are calling read_from_file function
                    self.read_from_file(command)
                else:
                    print "Invalid Command"
            elif ch == 2:
                break
            else:
                print "Choose correctly"

    @staticmethod
    def display_text(commands):
        # Here we are joining the text given and printing it
        text = ' '.join(commands[1:])
        print text

    @staticmethod
    def print_average(commands):
        # Here we are converting the given string to float if any error occurs displaying the text else printing avg
        try:
            count = 0
            sum = 0
            for num in commands[1:]:
                sum += float(num)
                count += 1
            print sum / count
        except:
            print "ERROR: usage: average <number> <number> .. <number>"

    @staticmethod
    def find_index(commands):
        # This function will find str2 in str1
        if len(commands[1:]) == 2:
            # If length is 2 then we will find the str2 in str1 else we will show the error message
            find_str = commands[2].replace("\n", "")
            # First here we are checking whether str2 is in str1 or not if it is there then we are printing index
            if find_str in commands[1]:
                print commands[1].index(find_str)
            else:
                print "String is not found!!"
        else:
            print "ERROR: usage: strstr <arg0> <arg1>"

    def read_from_file(self, commands):
        # Here we are reading the text from file line by line and we are processing that based on the given text
        file_name = commands[1].replace("\n", "")
        with open(file_name) as fd:
            content = fd.readlines()
            for line in content:
                split_line = line.split(' ')
                if split_line[0] == "echo":
                    # If first word is echo then we are calling display_text function
                    self.display_text(split_line)
                elif split_line[0] == "average":
                    # If first word is average then we are calling print_average function
                    self.print_average(split_line)
                elif split_line[0] == "strstr":
                    # If first word is strstr then we are calling find_index
                    self.find_index(split_line)
                elif split_line[0] == "script":
                    # If first word is  script then we are calling read_from_file function
                    self.read_from_file(split_line)
                else:
                    print "Invalid Command Line Arguments"


obj = ShellApplication()

*************************************Code Screens********************************

class ShellApplication: def init (self): # From here we are taking the data from user and based on the command given we are calling functions while True: print "-" print "1-Command\n2-stop" chinput) if ch1: print "Enter command:" commandraw input().split(" ") if command [0] "echo" 12 13 14 15 - # If first word is echo then we are calling display-text function self.display_text (command) command [0] # If first word is average then we are calling print-average function self.print_average(command) elif -"average": 18 elif command[]"strstr": # If first word is strstr then we are calling find-index self.find index (command) command [0] # If first word is script then we are calling read-from-file function self.read_from_file(command) elif "script": 23 else: 25 26 print Invalid Command" elif ch-2: break else: 28 29 30 print "Choose correctly" @staticmethod def display_text(commands) 32 34 35 36 # Here we are joining the text given and printing it text -join(commands [1:1) print text @staticmethod def print average(commands): 38 39 # Here we are converting the given string to float if any error occurs displaying the text else printing avg try 41 42 43 count sum0 for num in commands [1:]: sumfloat (num) count +1 45 46 print sumcount except 48 49 print "ERROR: usage: average <numer> <number>..<number>"

@staticmethod def find index(commands) 50 52 53 54 # This function will find str2 in str1 if len (commands [1:])2: # If length is 2 then we will find the str2 in stri else we will show the error message find str commands [2].replace("In", "") # First here we are checking whether str2 is in stri or not if it is there then we are printing index if find str in commands [1]: 56 print commands [1].index(find str) 58 59 60 else: print "String is not found!!" else: print "ERROR: usage: strstr <arge> <argl>" 63 64 65 def read from file(self, commands): # Here we are reading the text from file line by line and we are processing that based on the given text file namecommands [1].replace("In", "") with open(file_name) as fd: 68 69 content = fd, readlines() for line in content: split_line-line.split(' 71 72 73 74 75 76 if split-line [0]-"echo". elif split-line [0]-"average" elif split-line [0] --"strstr": # If first word is echo then we are calling display-text function self.display_text(split_line) # If first word is average then we are calling print-average function self.print_average(split_line) # If first word is strstr then we are calling find-index self.find_index(split_line) 78 80 elif split_linel0]"script" # If first word is script then we are calling read-from-file function self.read from file(split_line) 82 83 84 85 86 87 else: print "Invalid Command Line Arguments" obj - ShelLApplication()

*************************************Output Screens********************************

sys1091@sys1091:~/PycharmProjects/inboxer/tests python test.py 1-Command 2-stop Enter command: echo hello world hello world 1-Command 2-stop Enter command: hi Invalid Command 1-Command 2-stop Enter command: echo h:i 1-Command 2-stop Enter command: average 1 2 3 1-Command 2-stop Enter command: average 1 hi ERROR: usage: average <number> <number> .. <number> 1-Command 2-stop Enter command: strstr findhere here 4 1-Command 2-stop Enter command: strstr a b String is not found!!

1-Command 2-stop Enter command: strstr a RKK ERROR: usage: strstr <arg0> <argl> 1-Command 2-stop Enter command: strstr a b c RKK ERROR: usage: strstr <arg0> <argl> 1-Command 2-stop Enter command: script 1.txt RKK This is my introduction!!! 3.Θ ERROR: usage: strstr <arg0> <argl> hello ERROR: usage : average <number> number» くnumber> .. ERROR: usage : strstr «arge> <arg1> Invalid Command Line Arguments 1-Command 2-stop

sys1091@sys1091:/PycharmProjects/inboxer/tests cat 1.txt echo This is my introduction!! average 2 1 3 3 6 average hi 2 strstr a strstr pinecone cone script 2.txt sys1091@sys1091:~/PycharmProjects/inboxer/tests cat 2.txt echo hello average 2 345 strstr where e strstr where is the sys1091@sys1091:~/PycharmProjects/inboxer/tests python test.py 1-Command 2-stop Enter command: script 1.txt RKK This is my introduction!!! 3.0 ERROR: usage: average <number> <number> .. <number> ERROR: usage: strstr <argo> <argl> hello ERROR: Inval strstr id Command Line Arguments usage : «arge> <arg1> 1-Command 2-stop sys1091@sys1091:~/PycharmProjects/inboxer/tests