语句输出《Python for Beginners》学习笔记（3） 语句输出
PS:今天上午，非常郁闷，有很多简单基础的问题搞得我有些迷茫，哎，代码几天不写就忘。目前又不当COO，还是得用心记代码哦！《Python for Beginners》为LearnStreet上的Python入门课程。本节要主学习容内为条件语句。
Lesson 4 Control Flow and Conditionals
1. 第一个Python数函
1 def check_wounds():
2 #your code here
3 arms = 0
4 if arms == 1:
5 return "tis but a scratch"
6 elif arms == 0:
7 return "flesh wound"
8 else:
9 return "cross bridge"
10
11 #This is just for you to see what happens when the function is called
12 print check_wounds()
输出结果：
flesh wound
2. if语句
1 def always_true():
2 if 1 == 1:
3 #insert your code here
4 return "complete"
5
6 #This is just for you to see what happens when the function is called
7 print always_true()
输出结果：
complete
3. 再来一个if语句
1 flag = "unchanged"
2 def always_false():
3 global flag
4 if 1==2:
5 flag = "changed"
6
7 #This is just for you to see what happens when the function is called
8 always_false()
9 print flag
输出结果：
unchanged
4. else语句
1 def check_condition():
2 #return this if the condition is True
3 ifRun = "if code block run"
4
5 #return this is if the condition is False
6 elseRun = "else code block run"
7
8 condition = 0
9
10 if condition == True:
11 #your code here
12 return ifRun
13 else:
14 #your code here
15 return elseRun
16
17 #This is just for you to see what happens when the function is called
18 print check_condition()
输出结果：
else code block run
5. elif语句
1 def colorful_conditions():
2
3 color = "blue"
4
5 ifcolor == "red":
6 return "first block"
7 elifcolor == "white":
8 return "second block"
9 elifcolor == "blue":
10 return "third block"
11 else:
12 return "fourth block"
13
14 #This is just for you to see what happens when the function is called
15 print colorful_conditions()
输出结果：
third block
6. if语句训练
问题：
When the string phrase is fewer than 30 characters long, return 1. When it is exactly 30 return 2, and when it is greater than 30 return 3.
代码：
1 def check_length(phrase):
2 # your if condition here
3 if len(phrase) < 30:
4 return 1
5 # your elif condition here
6 elif len(phrase) == 30:
7 return 2
8 # your else condition here
9 else:
10 return 3
11
12 #This is just for you to see what happens when the function is called
13 print check_length("hi, i am a phrase")
输出结果：
1
7. if语句训练2
1 """
2 This function should check the value of the num variable and
3 return the string representation of the interval it is inUse if, elif,
4 and else statements to check if num falls in the range 1-5, 6-10,
5 11-15, or 16-20. Then return the correct interval as a string, like
6 "1-5", "6-10", "11-15", or "16-20".
7 """
8 def check_interval():
9 #Your code here
10 num = 5
11 if num < 6:
12 return "1-5"
13 elif num < 11:
14 return "6-10"
15 elif num < 16:
16 return "11-15"
17 else:
18 return "16-20"
19
20 #This is just for you to see what happens when the function is called
21 print check_interval()
输出结果：
1-5
8. and操作符
1 def should_eat(hungry, awake):
2 #your if statement here
3 if hungry and awake:
4 return "eat"
5 else:
6 return "don't eat"
7
8 #This is just for you to see what happens when the function is called
9 print should_eat(True, True)
输出结果：
eat
9. or操作符
1 def kitchen_or_bed(hungry, thirsty):
2 # your if statement here
3 if hungry or thirsty:
4 return "go to kitchen"
5 else:
6 return "go to bed"
7
8 #This is just for you to see what happens when the function is called
9 print kitchen_or_bed(True, True)
输出结果：
go to kitchen
10. 复习
1 def who_are_you(green, large):
2 # Write if-elif-else statements below
3 if green and large:
4 return "hulk"
5 elif green:
6 return "alien"
7 elif large:
8 return "elephant"
9 else:
10 return "Bruce Banner"
11
12 #This is just for you to see what happens when the function is called
13 print who_are_you(True, True)
输出结果：
hulk
总结：
1）注意缩进的格式
2）#开头为注释一行代码
3）注意数函定义以及条件语句后面的冒号
4）字符串可以直接作为数函的实参
（本文完）
文章结束给大家分享下程序员的一些笑话语录： 警告
有一个小伙子在一个办公大楼的门口抽着烟，一个妇女路过他身边，并对他 说， “你知道不知道这个东西会危害你的健康？我是说， 你有没有注意到香烟 盒上的那个警告（Warning）？”
小伙子说，“没事儿，我是一个程序员”。
那妇女说，“这又怎样？”
程序员说，“我们从来不关心 Warning，只关心 Error”
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