python基础（一）

一、你最喜欢的人

name = input('What is your name? ')
favorite_person = input('What is your favorite person? ')
print(name + ' likes ' +favorite_person)

二、你的年龄是

birth_year = input('Your  year of birth: ')
age = str(2020 - int(birth_year))
print('Your age is ' + age)

三、名字

name = 'Jennifer'
print(name[1:-1])
print(name[0:5])
#打印字符串的长度
print(len(name))
# 找到 i 的索引
print(name.find('i'))
# 替换字符
print(name.replace('fer','ger'))
# 判断文本是否有特定字符
print('er' in name)
#对文本进行大小写
print(name.upper())
print(name.lower())

四、杨[旭东] is a coder

first = '杨'
last = '旭东'
#f的意思是格式化
message = f'{first} [{last}] is a coder'
print(message)

五、数字处理

math.floor() 向下取整
math.ceil() 向上取整
round() 四舍五入

六、if-else 语句

is_hot = True
is_cold = False
if is_hot:
        print("Drink plenty of water")
elif is_cold:
        print("Wear warm cloths")
else:
        print("It's a lovely day")

七、逻辑运算符

and or not（与 或 非）

八、while 循环

secret_number = 9
guess_count = 0
guess_limit = 3
while guess_count < guess_limit:
        guess = int(input('Guess: '))
        guess_count += 1
if guess == secret_number:
        print('You won!')
        break
else:
        print('Sorry you failed!')

九、不开两次车

command = ""
started = False
while True:
        command = input("> ").lower()
        if command == "start":
                if started:
                        print("Car is already started!")
        else:    
                started = True
                print("Car started...")
        elif command == "stop":
                if not started:
                print("Car is already stopped!")
        else:
                started = False
                print("Car stopped.")
        elif command == "help":
                print("""
                    start - to start the car
                    stop - to stop the car
                    quit - to quit
                """)
        elif command ==  "quit":
                break
        else:
                print("Sorry, I don't understand that！")

十、for循环与列表

1.列表的基本方法

numbers = [5,2,1,5,7,4]
# 在列表中添加元素
numbers.append(20)
# 在列表中的索引位置添加元素
numbers.insert(0,10)
#移除列表中的元素
numbers.remove(2)
# 清空列表
numbers.clear()
# 清空列表最后一个元素
numbers.pop(3)
#查找某个元素的个数
numbers.count(5)
#升序和降序
numbers.sort()
numbers.reverse()
#列表的复制
numbers2 = numbers.copy()

2.清空列表中的重复元素

numbers = [2,2,3,5,4,4,56,5,5,1,7]
uniques = []
for number in numbers:
        if number not in uniques:
                uniques.append(number)
print(uniques)

十一、元组与解压缩

coordinates = (1,2,3)
x,y,z = coordinates
print(y)#2

十二、字典

phone = input("Phone: ")
digits_mapping = {
        "1" : "One",
        "2" : "Two",
        "3" : "Three",
        "4" : "four",
        "5" : "five"
        #...
}
output = ""
for ch in phone:
        output += digits_mapping.get(ch,"!") + " "
print(output)

十三、自定义函数

def greet_user(first_name, last_name):
        print(f'Hi {first_name} {last_name}!')
        print('Welcome aboard')


print("Start")
greet_user("john", last_name="smith")
print("Finish")

十四、异常处理

try:
    age = int(input('Age: '))
    income = 20000
    risk = income / age
    print(age)
except ZeroDivisionError:
        print('Age cannot be 0.')
except ValueError:
        print('Invalid value')