《笨办法学Python3》练习十三：实参，拆包，变量

练习代码

from sys import argv
# read the WYSS section for how to run this
script, first, second, third = argv

print("The script is called:", script)
print("Your first variable is:", first)
print("Your second variable is:", second)
print("Your third variable is:", third)

Study Drills

1. Try giving fewer than three arguments to your script. See that error you get? See if you can explain it.

PS D:\docs\pylearn\lpthw> python ex13.py 1 2
Traceback (most recent call last):
  File "ex13.py", line 3, in <module>
    script, first, second, third = argv
ValueError: not enough values to unpack (expected 4, got 3)

你准备了四个变量，然而不是所有变量都被赋了值，所以会出错。

2. Write a script that has fewer arguments and one that has more. Make sure you give the unpacked variables good names.

from sys import argv

script, first = argv

print("The script name is:", script)
print("The first arg name is:", argv)

from sys import argv

script, one, two, three, four, five = argv

print("The script name is:", script)
print("arg1 is:", one)
print("arg2 is:", two)
print("arg3 is:", three)
print("arg4 is:", four)
print("arg5 is:", five)

3. Combine input with argv to make a script that gets more input from a user. Don’t overthink
   it. Just use argv to get something, and input to get something else from the user.

from sys import argv

script, name = argv

game = input("Hello, {}! What is your favorite Nintendo game? ".format(name))

print(f"Me Too! I think {game} is the best game ever!")

4. Remember that modules give you features. Modules. Modules. Remember this because we’ll need it later.

补充

1. argv也是string类型，同上一节提到的情况。