python入门（输入、输出、if else 判断流、while循环、for循环）

# -*- 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)

原文地址：https://www.cnblogs.com/56321pia/p/10129776.html