food = ‘meat‘
print("Is food == ‘meat‘? I predict True")
print(food ==‘meat‘)
print("\nIs food == ‘apple‘? I predict False")
print(food ==‘apple‘)
fruit = ‘banana‘
print("\nIs fruit == ‘banana‘? I predict True")
print(fruit ==‘banana‘)
print("\nIs fruit == ‘apple‘? I predict False")
print(fruit ==‘apple‘)
#输出结果：
Is food == ‘meat‘? I predict True
True
Is food == ‘apple‘? I predict False
False
Is fruit == ‘banana‘? I predict True
True
Is fruit == ‘apple‘? I predict False
False
‘‘‘ i1=‘apple‘ i2=‘Apple‘ print(i1 == i2) print(i1 != i2) print(i1 == i2.lower()) ‘‘‘ ‘‘‘ i3=20 i4=30 print(i3 == i4) print(i3 != i4) print(i3 > i4) print(i3 >= i4) print(i3 < i4) print(i3 <= i4) print(i3<=20 and i4<=20) print(i3<=20 or i4<=20) ‘‘‘ j=[‘apple‘,‘banan‘,‘orange‘] j1 = ‘apple‘ print(j1 in j) print(j1 not in j)
‘‘‘
alien_color = ‘green‘
if alien_color ==‘green‘:
print("You get 5 points")
#输出结果：You get 5 points
‘‘‘
alien_color = ‘green‘
if alien_color ==‘orange‘:
print("You get 5 points")
#输出结果：空
alien_color = ‘green‘
if alien_color ==‘green‘:
print("You shoot alien. You get 5 points")
‘‘‘
else:
print("You get 10 points")
‘‘‘
5-5 外星人颜色#3 ：将练习5-4中的if-else 结构改为if-elif-else 结构。
alien_color = ‘green‘
if alien_color ==‘green‘:
print("You got 5 points")
elif alien_color ==‘yellow‘:
print("You got 10 points")
else:
print("You got 15 points")
#输出结果：You got 5 points
备注：黄色和红色打印的消息的代码省略，只要把变量中的值改为黄色和红色即可。
age = 64
if age <2:
print("He is baby")
elif 2<=age<4 :
print("He just learn to walk")
elif 4<=age <13:
print("He is a child")
elif 13<=age <20:
print("He is teenager")
elif 20<= age <65:
print("He is a adult")
else:
print("He is a elderly")
#输出结果：He is a adult
favorite_fruit = [‘apple‘,‘orange‘,‘banana‘]
if ‘apple‘ in favorite_fruit:
print("You really like apple!")
if ‘orange‘ in favorite_fruit:
print("You really like orange!")
if ‘banana‘ in favorite_fruit:
print("You really like bananas!")
if ‘pear‘ in favorite_fruit:
print()
if ‘watermelon‘ in favorite_fruit:
print()
#输出结果：
You really like apple!
You really like orange!
You really like bananas!
users=["admin","crystal","James","Lily","Lucy"]
for user in users:
if user == "admin":
print("Hello admin, would you like to see a status report?")
else:
print("Hello " + user + ",thank you for logging in again.")
#输出结果：
Hello admin, would you like to see a status report?
Hello crystal,thank you for logging in again.
Hello James,thank you for logging in again.
Hello Lily,thank you for logging in again.
Hello Lucy,thank you for logging in again.
users=[]
if users:
for user in users:
if user == "admin":
print("Hello admin, would you like to see a status report?")
else:
print("Hello " + user + ",thank you for logging in again.")
else:
print("We need to find some users!")
#输出结果：
We need to find some users!
current_users =[‘admin‘,‘crystal‘,‘James‘,‘Lucy‘,‘Lily‘]
new_users = [‘Admin‘,‘Crystal‘,‘Jim‘,‘Candy‘,‘lily‘]
for new_user in new_users:
if new_user.lower() in [current_user.lower() for current_user in current_users]:
#[current_user.lower() for current_user in current_users] 列表不区分大小写，也就是列表解析
print(new_user + ",Please input other user")
else:
print(new_user + ",This user is not used")
#输出结果：
Admin,Please input other user
Crystal,Please input other user
Jim,This user is not used
Candy,This user is not used
lily,Please input other user
5-11 序数 ：序数表示位置，如1st和2nd。大多数序数都以th结尾，只有1、2和3例外。
numbers = [1,2,3,4,5,6,7,8,9]
for number in numbers:
if number ==1:
print("1st")
elif number == 2:
print("2nd")
elif number == 3:
print("3rd")
else:
print(str(number)+"th")
#输出结果
1st
2nd
3rd
4th
5th
6th
7th
8th
9th
python编程：从入门到实践----第五章：if语句>练习
原文：https://www.cnblogs.com/heiqiuxixi/p/12330141.html