day1-字符串拼接表达式break和continue

Posted 2020-10-18 Eason

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一字符串拼接方式

1. 用加号（+）拼接

name = ‘eason‘
age = 18

info = ‘‘‘---info:‘‘‘+ name +‘‘‘
age: ‘‘‘ + str(age)

print(info)

2. 用占位符（%）拼接

name = "eason"
age = 18

info = ‘‘‘-----info-----
name: %s
age: %d
 ‘‘‘ % (name,age)

print(info)

3. 用format方法拼接

1.关键字拼接（官方推荐）
name = "eason01"
age = 19

info = ‘‘‘-----info----
name: {_name}
age:: {_age}
‘‘‘.format(_name = name,_age = age)

print(info)

2.占位符拼接
name = "eason02"
age = 20

info = ‘‘‘-----info-----
name: {0}
age: {1}
‘‘‘.format(name,age)

print(info)

二表达式if...else...

场景一：用户登录验证

name = input("请输入用户名：")
pwd = input("请输入密码：")

if name == "alex" and pwd == "cmd":
    print("欢迎，alex!")
else:
    print("用户名密码错误！")

场景二：猜年龄游戏

age_of_oldboy = 22

guess_age = int(input("guess age:"))

if guess_age == age_of_oldboy:
    print("yes,you got it !")
elif guess_age < age_of_oldboy:
    print("think bigger!")
else:
    print("think smaller!")

三表达式for loop

最简单的循环10次

for i in range(10):
    print("loop:", i )

需求一，遇到小于5的循环次数就不走了，直接进入下一次循环

for i in range(0,10,2): #0 初始化值,10 序列长度, 2 步长
    if i < 5:
        continue #不往下走了，直接进入下一次loop
    print("loop",i)

需求二，遇到大于5的循环次数就不走了，直接退出

for i in range(10): #默认初始化值 0 ，步长为 1
    if i > 5:
        break # 不往下走了，直接跳出当前整个loop
    print("loop",i)

四表达式while

count = 0
while True:
    print("11111",count)
    count += 1
    if count == 100:
        print("2222")
        break

如何实现让用户不断的猜年龄，但只给最多3次机会，再猜不对就退出程序

my_age = 25

count = 0
while count < 3:
    user_input = int(input("input your guess num:"))
    if user_input == my_age:
        print("you got it!")
        break
    elif user_input < my_age:
        print("think bigger!")
    else:
        print("think smaller!")
    count += 1
else:
    print("you have tied too many times...")