标签：continue   while True   for   count   

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1. 输出“Hello world” (这是个仪式）
   变量名要求：a, 不能是数字开头 b，除了“_”以外不能包含其他特殊字符 c，包含大小写，数字，下划线 d，变量名要简单易懂表达所代表的东西 e，关键字不能成为变量名（and ,as,assert break class continue def del elif ………..）

定义变量 name = "Hello World"
print (name)

2.注释多行：（‘‘‘ ‘‘‘）
‘‘‘
多行注释，也可以打印多行
‘‘‘
打印多行：
例：
name = ‘alex‘
msg=‘‘‘
print ("my name is :" , {_name} )
name = "paoche ge"
‘‘‘.format(_name=name)
print (msg)
输出结果：
print ("my name is :" , alex )
name = "paoche ge"

3.用户输入（input）和格式化输出
例：用户输入（input）
username = input("type your username:")
print(username)
格式化输出
a,例：字符串拼接(‘‘‘ + ‘‘‘)
username = input ("username is :")
age = input("age is :")
job = input("job is:")
salary=input("salary is:")
info1=‘‘‘
------info1 is ‘‘‘ + username ‘‘‘-----------
username is : ‘‘‘+ username ‘‘‘
age is : ‘‘‘ +age ‘‘‘
job is : ‘‘‘+job ‘‘‘
salary is : ‘‘‘ + salary
print (info1)

b, 字符串拼接(‘‘‘ %s ‘‘‘) ,s= string 字符串
username = input ("username is :")
age = input("age is :")
job = input("job is:")
salary=input("salary is:")
info2=‘‘‘
------info2 is %s-----------
username is : %s
age is : %s
job is : %s
salary is : %s
‘‘‘%(username,username,age,job,salary)
print (info2)

c, 字符串拼接(‘‘‘ %s ‘‘‘) s= string %d=整数 int=强制为数字？
username = input ("username is :")
age = int(input("age is :"))
job = input("job is:")
salary=input("salary is:")
info3=‘‘‘
------info3 is %s-----------
username is : %s
age is : %d
job is : %s
salary is : %s
‘‘‘%(username,username,age,job,salary)
print (info3)

d, 字符串拼接（使用排序.format）
username = input ("username is :")
age = input("age is :")
job = input("job is:")
salary=input("salary is:")
info4=‘‘‘
------info4 is {0}-----------
username is : {0}
age is : {1}
job is : {2}
salary is : {3}
‘‘‘.format(username,age,job,salary)
print (info4)

e, 字符串拼接(.format)
username = input ("username is :")
age = input("age is :")
job = input("job is:")
salary=input("salary is:")
info5=‘‘‘
------info5 is {_username}-----------
username is : {_username}
age is : {_age}
job is : {_job}
salary is : {_salary}
‘‘‘.format(username=_username,
age=_age,
job=_job,
salary=_salary)
print (info5)

以上的输出（print）结果是:

**/Library/Frameworks/Python.framework/Versions/3.6/bin/python3.6 "/Users/a1/PycharmProjects/untitled3/day1/user input.py"
username is :alex
your job is:IT
your age is:23
salary is :232323

--------info 5 alex------
yourname is :alex
your job is :IT
your age is :23
your salary is :232323
**

4.密码加密
例：
username = input("username:")
password = getpass.getpass("password:")
print (username,password)

5.if 条件判断语句（）
例：
oldboy_age=55
age = input("guess oldboy age is :")

if oldboy_age == age
print("yes,you got it")
else
print("wrong ansser")

例：使用and 或是 or 连接符，满足条件才执行
username = ‘alex‘（错误的写法为 usename=alex ，表示是变量）
password = ‘123456‘
_username =input("please input your name:")
_pass=input("please input your password:")
if usename=_username and _pass=password:
print ("welcom login system")
else:
print("wrong user")

6. while 循环语句
   while True 循环语句：表示为真则执行，反之则执行else 语句
   例：
   count = 0
   while True:
   print ("count:",count)
   count = count +1 # count +=1 每次循环加1，打印显示循环后的数值

while True 和 if 一起循环判断语句
例：
age= 55
while True:
guess = int(input("guess age :"))
if guess == age:
print("yes,you got it.")
elif guess < age:
print("think older.")
else:
print ("think smaler")
输入结果如下
/Library/Frameworks/Python.framework/Versions/3.6/bin/python3.6 "/Users/a1/PycharmProjects/untitled3/day1/whiel True 循环.py"
guess age :34
think older.
guess age :56
think smaler
guess age :

加上条件：使用户最多可以猜错三次条件
或是while 加条件语句如（while count < 3 ）
定义计数器 count = 0, count += 1 每次循环+1
跳出循环break
例：
age= 55
count = 0
while True:
if count == 3:
break
guess = int(input("guess age :"))
if guess == age:
print("yes,you got it.")
elif guess < age:
print("think older.")
else:
print ("think smaler")
count += 1
执行的结果为：
/Library/Frameworks/Python.framework/Versions/3.6/bin/python3.6 "/Users/a1/PycharmProjects/untitled3/day1/whiel True 循环.py"
guess age :23
think older.
guess age :23
think older.
guess age :23
think older.

Process finished with exit code 0

对以上的代码做优化
例：
age = 55
count = 0
while count < 3:
guess = int(input("guess age: "))
if age == guess:
print ("yes ,you got it")
elif age < guess:
print ("think older")
else:
print ("think smaller")
count += 1

** # if count == 3:

print ("you have try too many times.")**

else:
print("you have try too many times.")
输出结果是：
/Library/Frameworks/Python.framework/Versions/3.6/bin/python3.6 "/Users/a1/PycharmProjects/untitled3/day1/whiel True 循环.py"
guess age: 34
think smaller
guess age: 35
think smaller
guess age: 78
think older
you have try too many times.

Process finished with exit code 0

6.for 循环
a,#最基本的for 循环
for i in range(10):
print(i)
输出结果：
0
1
2
3
4
5
6
7
8
9

b,显示不连续的数字(0:从0 开始，10:循环10次，2:每隔2位输出一个数字)
for i in range(0,10,2):
print (i)
输出结果为：
/Library/Frameworks/Python.framework/Versions/3.6/bin/python3.6 "/Users/a1/PycharmProjects/untitled3/day1/for 循环.py"
0
2
4
6
8
Process finished with exit code 0
c，使用for 循环 猜年龄
例：
age = 55
for i in range (3):
guess = int(input("guess age:"))
if guess == age:
print ("yes,you got it .")
break
elif guess < age:
print ("think older")
else:
print ("think smaller")
else:
print("you have trid too many times.")
输出结果：
/Library/Frameworks/Python.framework/Versions/3.6/bin/python3.6 "/Users/a1/PycharmProjects/untitled3/day1/for 循环.py"
guess age:34
think older
guess age:34
think older
guess age:34
think older
you have trid too many times.
Process finished with exit code 0

6.continue #跳出本次循环，执行下一次循环
while True:
for i in range(3):
user = int(input("guess age:"))
if user == age:
print("1")
elif user > age:
print(">")
elif user < age:
print("<")
con = input("do you want con?")

if con == ‘c‘:
    continue
else:
    break

age_of_oldboy = 55
count = 0
while count < 3:
age = int(input("please input age of oldboy:"))

if age_of_oldboy == age:
    print("yes ,you got it!")
    break
elif age_of_oldboy < age:
    print("think smaller")
else:
    print("think older")
    count += 1

if count == 3:
    continue_confirm = input("do you want to keep guessing..?")
    if continue_confirm  != ‘n‘:
        count = 0
        # != 不等于

python小白学习之路--01

标签：continue   while True   for   count   

原文地址：http://blog.51cto.com/2926352/2092616