python入门（输入输出if else 判断流while循环for循环）

Posted 2021-01-27 56321pia

# -*- coding:utf-8 -*-        ———————— 申明字符编码集

注释：当行 —    #

           多行 —    “”” “”” 或者 ‘’’ ‘’’  (在python中单引号双引号没有区别)

1、 输出

   print ("hello word !")

2、 变量

    定义编码：name = "hui"

    使用编码：print ("name is",name)  （变量之间逗号隔开）

    打印变量数据类型：print(type(name))

3、 用户输入

    输入格式：username = input(“username:”)

    转换输入数据类型：age=int( input(“password:”) )

    加密显示输入：

          import  getpass #引用密码包

          password = getpass.getpass("password:")

 4、格式化输出

    列：name = input("name:")

           age = input("age:")
           sex = input("sex:")
           height = input("height:")

          # 方式1：（字符串拼接用 +）--建议不使用

          msg = ‘‘‘------- msg of ‘‘‘ + name + ‘‘‘ -------
          name:‘‘‘ + name +‘‘‘
          age:‘‘‘ + age + ‘‘‘
          sex:‘‘‘ + sex + ‘‘‘
          height:‘‘‘ + height

          print (msg)

         方式2：占位符 %s （s——string简写）--不推荐

         msg = ‘‘‘------- msg of %s -------
         name:%s
         age:%s
         sex:%s
         height:%s
          ‘‘‘%(name,name,age,sex,height)

        print (msg)

       方式3：--不推荐

  msg = ‘‘‘------- msg of {0} ------- 

  name:{0}

  age:{1}

  sex:{2}

  height:{3}

  ‘‘‘.format(name,age,sex,height)

      print (msg)

  方式4：推荐使用

  msg = ‘‘‘------- msg of {name_1} ------- 

  name:{name_1}

  age:{age_1}

  sex:{sex_1}

  height:{height_1}

  ‘‘‘.format(name_1=name,

             age_1=age,

             sex_1=sex,

             height_1=height)
   print (msg)

4、 if else 流程判    username_a = ‘qaz‘ 

    password_a = ‘123‘

    username = input("username:")

    password = input("password:")

    if username == username_a and password == password_a:

        print("Welcome user {name} login...".format(name=username))

   else:

       print("Invalid username or password!")

 5、 while 循环

username_a = ‘qaz‘
password_a = ‘123‘
entry_count=0
while entry_count<3:
    username = input("username:")
    password = input("password:")
    if username == username_a and password == password_a:
        print("Welcome user {name} login...".format(name=username))
        break
    else:
        print("Invalid username or password! Please Try Again")
    entry_count +=1
else:
    print("you have tried too many times..fuck off")

6、 for 循环

for i in range (0,10,1):
    print(‘----------‘, i)
    for j in range(10):
        if j > 5:
            break
        else:
            print(j)