笨办法学 Python3 第五版（预览）（二）(1)

1   x = 10

1   def print_one(arg1):
2       print(f"arg1: {arg1}")

1   print_one("First!")

1   y = "First!"
2   print_one(y)

1   def print_one(arg1):
2       print(f"arg1: {arg1}")
3
4   y = "First!"
5   print_one(y)

1   def cheese_and_crackers(cheese_count, boxes_of_crackers):
 2       print(f"You have {cheese_count} cheeses!")
 3       print(f"You have {boxes_of_crackers} boxes of crackers!")
 4       print("Man that's enough for a party!")
 5       print("Get a blanket.\n")
 6
 7
 8   print("We can just give the function numbers directly:")
 9   cheese_and_crackers(20, 30)
10
11
12   print("OR, we can use variables from our script:")
13   amount_of_cheese = 10
14   amount_of_crackers = 50
15
16   cheese_and_crackers(amount_of_cheese, amount_of_crackers)
17
18
19   print("We can even do math inside too:")
20   cheese_and_crackers(10 + 20, 5 + 6)
21
22
23   print("And we can combine the two, variables and math:")
24   cheese_and_crackers(amount_of_cheese + 100, amount_of_crackers + 1000)

1   We can just give the function numbers directly:
 2   You have 20 cheeses!
 3   You have 30 boxes of crackers!
 4   Man that's enough for a party!
 5   Get a blanket.
 6
 7   OR, we can use variables from our script:
 8   You have 10 cheeses!
 9   You have 50 boxes of crackers!
10   Man that's enough for a party!
11   Get a blanket.
12
13   We can even do math inside too:
14   You have 30 cheeses!
15   You have 11 boxes of crackers!
16   Man that's enough for a party!
17   Get a blanket.
18
19   And we can combine the two, variables and math:
20   You have 110 cheeses!
21   You have 1050 boxes of crackers!
22   Man that's enough for a party!
23   Get a blanket.

1   from sys import argv
 2
 3   script, input_file = argv
 4
 5   def print_all(f):
 6       print(f.read())
 7
 8   def rewind(f):
 9       f.seek(0)
10
11   def print_a_line(line_count, f):
12       print(line_count, f.readline())
13
14   current_file = open(input_file)
15
16   print("First let's print the whole file:\n")
17
18   print_all(current_file)
19
20   print("Now let's rewind, kind of like a tape.")
21
22   rewind(current_file)
23
24   print("Let's print three lines:")
25
26   current_line = 1
27   print_a_line(current_line, current_file)
28
29   current_line = current_line + 1
30   print_a_line(current_line, current_file)
31
32   current_line = current_line + 1
33   print_a_line(current_line, current_file)

1   First let's print the whole file:
 2
 3   This is line 1
 4   This is line 2
 5   This is line 3
 6
 7   Now let's rewind, kind of like a tape.
 8   Let's print three lines:
 9   1 This is line 1
10
11   2 This is line 2
12
13   3 This is line 3

1   def add(a, b):
 2       print(f"ADDING {a} + {b}")
 3       return a + b
 4
 5   def subtract(a, b):
 6       print(f"SUBTRACTING {a} - {b}")
 7       return a - b
 8
 9   def multiply(a, b):
10       print(f"MULTIPLYING {a} * {b}")
11       return a * b
12
13   def divide(a, b):
14       print(f"DIVIDING {a} / {b}")
15       return a / b
16
17
18   print("Let's do some math with just functions!")
19
20   age = add(30, 5)
21   height = subtract(78, 4)
22   weight = multiply(90, 2)
23   iq = divide(100, 2)
24
25   print(f"Age: {age}, Height: {height}, Weight: {weight}, IQ: {iq}")
26
27
28   # A puzzle for the extra credit, type it in anyway.
29   print("Here is a puzzle.")
30
31   what = add(age, subtract(height, multiply(weight, divide(iq, 2))))
32
33   print("That becomes: ", what, "Can you do it by hand?")

1   Let's do some math with just functions!
 2   ADDING 30 + 5
 3   SUBTRACTING 78 - 4
 4   MULTIPLYING 90 * 2
 5   DIVIDING 100 / 2
 6   Age: 35, Height: 74, Weight: 180, IQ: 50.0
 7   Here is a puzzle.
 8   DIVIDING 50.0 / 2
 9   MULTIPLYING 180 * 25.0
10   SUBTRACTING 74 - 4500.0
11   ADDING 35 + -4426.0
12   That becomes: -4391.0 Can you do it by hand?