PYTHON入门教程5-- Conditionals & Control Flow
37 介绍了条件语句if
38 if的格式如下, 比如
[python]
if 8 < 9:
print "Eight is less than nine!"
3 另外还有这elif 以及else，格式如下
[python]
if 8 < 9:
print "I get printed!"
elif 8 > 9:
print "I don't get printed."
else:
print "I also don't get printed!"
4 练习：设置变量response的值为'Y'
[python]
response = 'Y'
answer = "Left"
if answer == "Left":
print "This is the Verbal Abuse Room, you heap of parrot droppings!"
# Will the above print statement print to the console?
# Set response to 'Y' if you think so, and 'N' if you think not.
第十节
1 介绍了if的格式
[python]
if EXPRESSION:
# block line one
# block line two
# et cetera
2 练习：在两个函数里面加入两个加入条件语句，能够成功输出
[python]
def using_control_once():
if 1 > 0:
return "Success #1"
def using_control_again():
if 1 > 0:
return "Success #2"
print using_control_once()
print using_control_again()
39 介绍了else这个条件语句
2 练习：完成函数里面else条件语句
[python]
answer = "'Tis but a scratch!"
def black_knight():
if answer == "'Tis but a scratch!":
return True
else:
return False # Make sure this returns False
def french_soldier():
if answer == "Go away, or I shall taunt you a second time!":
return True
else:
return False # Make sure this returns False
40 介绍了另外一种条件语句elif的使用
2 练习：在函数里面第二行补上answer > 5， 第四行补上answer < 5 , 从而完成这个函数
[python]
def greater_less_equal_5(answer):
if answer > 5:
return 1
elif answer < 5:
return -1
else:
return 0
print greater_less_equal_5(4)
print greater_less_equal_5(5)
print greater_less_equal_5(6)
第十三节
1 练习：利用之前学的比较以及连接符以及条件语句补全函数。所有的都要出现至少一次
[python]
def the_flying_circus():
# Start coding here!
if 1 < 2 and not False:
return True
elif 1 == 1 or 1 != 2 or 1 < 2 or 1 <= 2 or 1 > 2 or 1 >= 2:
return True
else:
return False
