"Learn Python the Hard Way"学习笔记2——Exercsie1-8

Exercise 1 第一个程序

在Notepad++输入代码，保存为ex1.py

print "Hello World!"
print "Hello Again"
print "I like typing this"
print "This is fun"
print 'Yay! Printing.'
print "I'd much rather you 'not'."
print 'I "said" do not touch this.'

在PowerShell里执行程序

python ex1.py

Exercise 2 注释和'#'

#A comment,this is so you can read your program later.
#Anything after the # is ignored by python.

print "I could have code like this." #and the comment after is ignored

#You can also use a comment to "disable" or comment out a piece of code:
#print "This won't run"

print "This will run."

Exercise 3 数字和数学

print "I will now count my chickens:"

print "Hens", 25 + 30 / 6
print "Roosters", 100 - 25 * 3 % 4

print "Now I will count the eggs:"

print 3 + 2 + 1 - 5 + 4 % 2 - 1 / 4 + 6

print "Is it true that 3 + 2 < 5 - 7?"

print 3 + 2 < 5 - 7

print "What is 3 +2?", 3 + 2

Exercise 4 变量和命名

cars = 100
space_in_a_car = 4.0
drivers = 30
passengers = 90
cars_not_driven = cars - drivers
cars_driven = drivers
carpool_capacity = cars_driven * space_in_a_car
average_passengers_per_car = passengers / cars_driven


print "There are", cars, "cars available."
print "There are only", drivers, "drivers available."
print "There will be", cars_not_driven, "empty cars today."
print "We can transport", carpool_capacity, "people today."
print "We have", passengers, "to carpool today."
print "We need to put about", average_passengers_per_car,"in each car."

Exercise 5 更多的变量和输出

his_name = 'Zed A. Shaw'
his_age = 35 #not a lie hhh
his_height = 74 #inches
his_weight = 180 #lbs
his_eyes = 'Blue'
his_teeth = 'White'
his_hair = 'Brown'

print "Let's talk about %s." % his_name
print "He's %d inches tall." % his_height
print "He's %d pounds heavy." % his_weight
print "Actually that's not too heavy."
print "He's got %s eyes and %s hairs." % (his_eyes, his_hair)
print "His teeth are usually %s depending on the coffee." % his_teeth

#this line is tricky, try to get it exactly right
print "If I add %d, %d, and %d I get %d." % (his_age, his_height, his_weight, his_age + his_weight + his_height)

Exercise 6 字符串和文本

x = "There are %d types of people." % 10
binary = "binary"
do_not = "don't"
y = "Those who know %s and those who %s." % (binary, do_not)

print x 
print y 

print "I said: %r." % x 
print "I also said: '%s'." % y 

hilarious = False 
joke_evaluation = "Isn't that joke so funny?! %r"

print joke_evaluation % hilarious

w = "This is the left side of..."
e = "a string with a right side."

print w + e 

执行结果如下：

output6.png

用%r显示的是变量“原始”的数据值，%r在打印的时候能够重现它代表的对象，但其他的符号用来给用户显示变量值。看下面的例子理解一下：

text = "I am %d years old." % 22
print "I said: %s." % text
print "I said: %r." % text

返回的结果：

I said: I am 22 years old..
I said: 'I am 22 years old.'. // %r 给字符串加了单引号

Exercise 7 输出更多

print "Mary had a little lamb."
print "Its fleece was white as %s." % 'snow'
print "And everywhere that Mary went."
print "." * 10 #What'd that do?

end1 = "C"
end2 = "h"
end3 = "e"
end4 = "e"
end5 = "s"
end6 = "e"
end7 = "B"
end8 = "u"
end9 = "r"
end10 = "g"
end11 = "e"
end12 = "r"

#Watch that comma at the end. try removing it to see what happens
print end1 + end2 + end3 + end4 + end5 + end6,
print end7 + end8 + end9 + end10 + end11 + end12

Exercise 8 输出，输出

formatter = "%r %r %r %r"

print formatter % (1, 2, 3, 4)
print formatter % ("one", "two", "three", "four")
print formatter % (True, False, False, True)
print formatter % (formatter, formatter, formatter, formatter)
print formatter % (
    "I had a thing.",
    "That you could type up right.",
    "But it didn't sing.",
    "So I said goodnight."
    ) 

执行结果如下：

output8.png