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0x02-python-import_modules

README.md

0x02. Python - import & modules

Resources

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python3

Requirements

General

  • Allowed editors: vi, vim, emacs
  • All your files will be interpreted/compiled on Ubuntu 20.04 LTS using python3 (version 3.8.5)
  • All your files should end with a new line
  • The first line of all your files should be exactly #!/usr/bin/python3
  • A README.md file, at the root of the folder of the project, is mandatory
  • Your code should use the pycodestyle (version 2.8.*)
  • All your files must be executable
  • The length of your files will be tested using wc

Tasks

0. Import a simple function from a simple file

Write a program that imports the function def add(a, b): from the file add_0.py and prints the result of the addition 1 + 2 = 3

  • You have to use print function with string format to display integers
  • You have to assign:
    • the value 1 to a variable called a
    • the value 2 to a variable called b
    • and use those two variables as arguments when calling the functions add and print
  • a and b must be defined in 2 different lines: a = 1 and another b = 2
  • Your program should print: <a value> + <b value> = <add(a, b) value> followed with a new line
  • You can only use the word add_0 once in your code
  • You are not allowed to use * for importing or __import__
  • Your code should not be executed when imported - by using __import__, like the example below
guillaume@ubuntu:~/0x02$ cat add_0.py
#!/usr/bin/python3
def add(a, b):
    """My addition function

    Args:
        a: first integer
        b: second integer

    Returns:
        The return value. a + b
    """
    return (a + b)

guillaume@ubuntu:~/0x02$ ./0-add.py
1 + 2 = 3
guillaume@ubuntu:~/0x02$ cat 0-import_add.py
__import__("0-add")
guillaume@ubuntu:~/0x02$ python3 0-import_add.py
guillaume@ubuntu:~/0x02$

1. My first toolbox!

Write a program that imports functions from the file calculator_1.py, does some Maths, and prints the result.

  • Do not use the function print (with string format to display integers) more than 4 times
  • You have to define:
    • the value 10 to a variable a
    • the value 5 to a variable b
    • and use those two variables only, as arguments when calling functions (including print)
  • a and b must be defined in 2 different lines: a = 10 and another b = 5
  • Your program should call each of the imported functions. See example below for format
  • the word calculator_1 should be used only once in your file
  • You are not allowed to use * for importing or __import__
  • Your code should not be executed when imported
guillaume@ubuntu:~/0x02$ cat calculator_1.py
#!/usr/bin/python3
def add(a, b):
    """My addition function

    Args:
        a: first integer
        b: second integer

    Returns:
        The return value. a + b
    """
    return (a + b)


def sub(a, b):
    """My subtraction function

    Args:
        a: first integer
        b: second integer

    Returns:
        The return value. a - b
    """
    return (a - b)


def mul(a, b):
    """My multiplication function

    Args:
        a: first integer
        b: second integer

    Returns:
        The return value. a * b
    """
    return (a * b)


def div(a, b):
    """My division function

    Args:
        a: first integer
        b: second integer

    Returns:
        The return value. a / b
    """
    return int(a / b)

guillaume@ubuntu:~/0x02$ ./1-calculation.py
10 + 5 = 15
10 - 5 = 5
10 * 5 = 50
10 / 5 = 2
guillaume@ubuntu:~/0x02$

2. How to make a script dynamic!

Write a program that prints the number of and the list of its arguments.

  • The output should be:
    • Number of argument(s) followed by argument (if number is one) or arguments (otherwise), followed by
    • : (or . if no arguments were passed) followed by
    • a new line, followed by (if at least one argument),
    • one line per argument:
      • the position of the argument (starting at 1) followed by :, followed by the argument value and a new line
  • Your code should not be executed when imported
  • The number of elements of argv can be retrieved by using: len(argv)
  • You do not have to fully understand lists yet, but imagine that argv can be used just like a C array: you can use an index to walk through it. There are other ways (which will be preferred for future project tasks), if you know them you can use them.
guillaume@ubuntu:~/0x02$ ./2-args.py 
0 arguments.
guillaume@ubuntu:~/0x02$ ./2-args.py Hello
1 argument:
1: Hello
guillaume@ubuntu:~/0x02$ ./2-args.py Hello Welcome To The Best School
6 arguments:
1: Hello
2: Welcome
3: To
4: The
5: Best
6: School
guillaume@ubuntu:~/0x02$

3. Infinite addition

Write a program that prints the result of the addition of all arguments

  • The output should be the result of the addition of all arguments, followed by a new line
  • You can cast arguments into integers by using int() (you can assume that all arguments can be casted into integers)
  • Your code should not be executed when imported
guillaume@ubuntu:~/0x02$ ./3-infinite_add.py
0
guillaume@ubuntu:~/0x02$ ./3-infinite_add.py 79 10
89
guillaume@ubuntu:~/0x02$ ./3-infinite_add.py 79 10 -40 -300 89 
-162
guillaume@ubuntu:~/0x02$

Last but not least, your program should also handle big numbers. And the good news is: if your program works for the above example, it will work for the following example:

guillaume@ubuntu:~/0x02$ ./3-infinite_add.py 1111111111111111111111111111111111111111111111111111111111112222222222222222222222222222222222223435467866765443534434222222254444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555666666666666666666666666666666777777777777777777777777777777888888888888888888888888888888899999999999999999999999990000000000000000000 11111111111111111111111111111111111111111111111111222222222222222222222222222333333333333333333334567788888899999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999
11111111111111111111111111111111111111111111111111222222222222222222222222222333333333333333333334568900000011111111111111111111111111111111111111111111111111112222222222222222222222222222222222223435467866765443534434222222254444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555666666666666666666666666666666777777777777777777777777777777888888888888888888888888888888899999999999999999999999989999999999999999999
guillaume@ubuntu:~/0x02$

Remember how you did (or did not) do it in C? #pythoniscool 621c6dd72e1acff708141f3fab6dfa6ff37c5ee6

4. Who are you?

Write a program that prints all the names defined by the compiled module hidden_4.pyc (please download it locally).

  • You should print one name per line, in alpha order
  • You should print only names that do not start with __
  • Your code should not be executed when imported
  • Make sure you are running your code in Python3.8.x (hidden_4.pyc has been compiled with this version)
guillaume@ubuntu:~/0x02$ curl -Lso "hidden_4.pyc" "https://github.com/holbertonschool/0x02.py/raw/master/hidden_4.pyc"
guillaume@ubuntu:~/0x02$ ./4-hidden_discovery.py | sort
my_secret_santa
print_hidden
print_school
guillaume@ubuntu:~/0x02$

5. Everything can be imported

Write a program that imports the variable a from the file variable_load_5.py and prints its value.

  • You are not allowed to use * for importing or __import__
  • Your code should not be executed when imported
guillaume@ubuntu:~/0x02$ cat variable_load_5.py
#!/usr/bin/python3
a = 98
"""Simple variable
"""

guillaume@ubuntu:~/0x02$ ./5-variable_load.py
98
guillaume@ubuntu:~/0x02$

6. Build my own calculator!

Write a program that imports all functions from the file calculator_1.py and handles basic operations.

  • Usage: ./100-my_calculator.py a operator b
    • If the number of arguments is not 3, your program has to:
      • print Usage: ./100-my_calculator.py <a> <operator> <b> followed with a new line
      • exit with the value 1
    • operator can be:
      • + for addition
      • - for subtraction
      • * for multiplication
      • / for division
    • If the operator is not one of the above:
      • print Unknown operator. Available operators: +, -, * and / followed with a new line
      • exit with the value 1
    • You can cast a and b into integers by using int() (you can assume that all arguments will be castable into integers)
    • The result should be printed like this: <a> <operator> <b> = <result>, followed by a new line
  • You are not allowed to use * for importing or __import__
  • Your code should not be executed when imported
guillaume@ubuntu:~/0x02$ cat calculator_1.py
#!/usr/bin/python3
def add(a, b):
    """My addition function

    Args:
        a: first integer
        b: second integer

    Returns:
        The return value. a + b
    """
    return (a + b)


def sub(a, b):
    """My subtraction function

    Args:
        a: first integer
        b: second integer

    Returns:
        The return value. a - b
    """
    return (a - b)


def mul(a, b):
    """My multiplication function

    Args:
        a: first integer
        b: second integer

    Returns:
        The return value. a * b
    """
    return (a * b)


def div(a, b):
    """My division function

    Args:
        a: first integer
        b: second integer

    Returns:
        The return value. a / b
    """
    return int(a / b)

guillaume@ubuntu:~/0x02$ ./100-my_calculator.py ; echo $?
Usage: ./100-my_calculator.py <a> <operator> <b>
1
guillaume@ubuntu:~/0x02$ ./100-my_calculator.py 3 + 5 ; echo $?
3 + 5 = 8
0
guillaume@ubuntu:~/0x02$ ./100-my_calculator.py 3 H 5 ; echo $?
Unknown operator. Available operators: +, -, * and /
1
guillaume@ubuntu:~/0x02$

7. Easy print

Write a program that prints #pythoniscool, followed by a new line, in the standard output.

  • Your program should be maximum 2 lines long
  • You are not allowed to use print or eval or open or import sys in your file 101-easy_print.py
guillaume@ubuntu:~/0x02$ ./101-easy_print.py
#pythoniscool
guillaume@ubuntu:~/0x02$

8. ByteCode -> Python #3

Write the Python function def magic_calculation(a, b): that does exactly the same as the following Python bytecode:

3           0 LOAD_CONST               1 (0)
              3 LOAD_CONST               2 (('add', 'sub'))
              6 IMPORT_NAME              0 (magic_calculation_102)
              9 IMPORT_FROM              1 (add)
             12 STORE_FAST               2 (add)
             15 IMPORT_FROM              2 (sub)
             18 STORE_FAST               3 (sub)
             21 POP_TOP

  4          22 LOAD_FAST                0 (a)
             25 LOAD_FAST                1 (b)
             28 COMPARE_OP               0 (<)
             31 POP_JUMP_IF_FALSE       94

  5          34 LOAD_FAST                2 (add)
             37 LOAD_FAST                0 (a)
             40 LOAD_FAST                1 (b)
             43 CALL_FUNCTION            2 (2 positional, 0 keyword pair)
             46 STORE_FAST               4 (c)

  6          49 SETUP_LOOP              38 (to 90)
             52 LOAD_GLOBAL              3 (range)
             55 LOAD_CONST               3 (4)
             58 LOAD_CONST               4 (6)
             61 CALL_FUNCTION            2 (2 positional, 0 keyword pair)
             64 GET_ITER
        >>   65 FOR_ITER                21 (to 89)
             68 STORE_FAST               5 (i)

  7          71 LOAD_FAST                2 (add)
             74 LOAD_FAST                4 (c)
             77 LOAD_FAST                5 (i)
             80 CALL_FUNCTION            2 (2 positional, 0 keyword pair)
             83 STORE_FAST               4 (c)
             86 JUMP_ABSOLUTE           65
        >>   89 POP_BLOCK

  8     >>   90 LOAD_FAST                4 (c)
             93 RETURN_VALUE

 10     >>   94 LOAD_FAST                3 (sub)
             97 LOAD_FAST                0 (a)
            100 LOAD_FAST                1 (b)
            103 CALL_FUNCTION            2 (2 positional, 0 keyword pair)
            106 RETURN_VALUE
            107 LOAD_CONST               0 (None)
            110 RETURN_VALUE

9. Fast alphabet

Write a program that prints the alphabet in uppercase, followed by a new line.

  • Your program should be maximum 3 lines long
  • You are not allowed to use:
    • any loops
    • any conditional statements
    • str.join()
    • any string literal
    • any system calls
guillaume@ubuntu:~/0x02$ ./103-fast_alphabet.py
ABCDEFGHIJKLMNOPQRSTUVWXYZ
guillaume@ubuntu:~/0x02$ wc -l 103-fast_alphabet.py
3 103-fast_alphabet.py
guillaume@ubuntu:~/0x02$