Python基础（一）

一、python的版本

python版本分为2系列和3系列，但是目前大部分企业都使用2系列版本，但是3系列python版本已经成为趋势，因此本博客主要以3系列的python版本为主。

二、变量

变量即是预先定义的值，主要用于方便脚本编写，方便脚本调用。变量通常以数字、字母及下划线开头，例：1_pass 、_pass 、pass都可以作为变量使用，但是特殊字符不可以

例：

print("hello world")
name = "xiao yu"
name2 = name
print("My name is ",name,name2)
name = "lala"
print("My name is ",name,name2)    ##后面这个name会显示lala，而name2会显示xiaoyu，因为name2指向的是内存中xiaoyu这个位置

name = "xiaoyu"
msg =  '''
name2 = name
print("My name is",name,name2)
'''
print(msg)

age = int(input("age:")) #integer
print(type(age) ,type(str(age)) )
job = input("job:")
salary = input("salary:")

info3 = '''
-------- info of  {0}---
Name:{0}
Age:{1}
Job:{2}
Salary:{3}
''' .format(name,age,job,salary)
print(info3)

三、字符编码与二进制

ASCII、unicode、utf-8、GB2312

四、用户交互

input命令：输入的所有字符都以字符串表示

例：name = input("name:") 

print(type(name))

str

五、if、else流程判断

条件判断：如果、否则。例：

_username = 'xiaoyu'
_password = 'xiaoyu123'
username = input("username:")
#password = getpass.getpass("password:")
password = input("password:")
if _username == username and _password == password:
    print("Welcome user {name} login...".format(name=username))
else:
    print("Invalid username or password")

print(username, password)

六、while循环

例：

Age_of_Dulant=50
count = 0
while True:
    if count == 3:
         break
    Guess_age = int(input("ips age:"))
    if Guess_age == Age_of_Dulant:
       print("very smart!")
        break
   elif Guess_age > Age_of_Dulant:
       print("think smaller!")
   else:
       print("think bigger")
   count += 1

Age_of_Dulant=50
count = 0
while count < 3:
    Guess_age = int(input("ips age:"))
    if Guess_age == Age_of_Dulant:
        print("very smart!")
        break
    elif Guess_age > Age_of_Dulant:
        print("think smaller!")
    else:
       print("think bigger")
    count += 1
    if count == 3:
        continue_confirm = input("do you want to keep guessing:")
        if continue_confirm != 'n':
            count = 0

七、for循环

例：

#Age_of_Dulant=50
#for i in range(3):
#    Guess_age = int(input("ips age:"))
#    if Guess_age == Age_of_Dulant:
#        print("very smart!")
#        break
#    elif Guess_age > Age_of_Dulant:
#        print("think smaller!")
#    else:
#        print("think bigger")
#else:    ##表示若上面for循环完成，则执行此else，否则，不执行
#    print("you have try too many times,fuck off!")

#for i in range(10):
#    if i < 4:
#        print("loop:",i)
#    else:
#        continue
#    print("hehe...")

for i in range(10):
    print("_________:",i)
    for j in range(10):
        print(j)
        if j > 5:
            break