学习1：python输入输出

1. 输出

>>> print "hello world"
hello world
>>> print 'hello world'
hello world
>>> print 'Hello','world'
Hello world
>>> print "I'm studing python"
I'm studing python
>>> print 'I am studing "python"'
I am studing "python"
>>> print "I'm studing \"python\""
I'm studing "python"
>>> print 'I\'m studing "python"'
I'm studing "python"
>>> print '''I'm studing "python"'''
I'm studing "python"
>>> print '''I am
... studing
... "python"'''
I am
studing
"python"

>>> print "Name:%s Age:%d Height:%f" %('Tester',18,1.80)
Name:Tester Age:18 Height:1.800000
>>> print "Name:%8s Age:%3d Height:%5.2f" %('Tester',18,1.80)
Name:  Tester Age: 18 Height: 1.80
>>> print "Name:%-8s Age:%-3d Height:%-5.2f" %('Tester',18,1.80)
Name:Tester   Age:18  Height:1.80 
>>> print "Name:%s Age:%3d Height:%*.*f" % ('Tester',18,6,2,1.80)
Name:Tester Age: 18 Height:  1.80
print "Name:%r Age:%r Height:%r" %('Tester',18,1.80)
Name:'Tester' Age:18 Height:1
>>> print '12',3
12 3
>>> print '12'+3
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: cannot concatenate 'str' and 'int' objects
>>> print '12'+'3'
123
>>> print 12+3
15

　　

总结：
1) print 输出字符串可以使用''或者""表示；
2) print后可以有多个输出，以逗号分隔，最终逗号以空格输出，两边类型可以不一致；
也可以用+号连接，但是+号要求两边类型必须一致，连接数字表示相加，连接字符串表示相连；
3) 如果字符串本身包含""，可以使用''来表示；如果字符串本身包含''，可以使用""来表示;
4) 如果字符串本身既包含''也包含""，可以使用\进行转义；常用转义字符：\n 换行； \t制表符； \\ 表示\本身
5) 如果字符串本身既包含''也包含""，也可以使用'''来表示；'''一般用于输出多行文本中；
6) 格式化输出可以指定输出字段的长度，%5.2f表示输出浮点数的小数点后有2位，总共长度为5位，默认为右对齐，不足的左侧补空格；
%-5.2f表示左对齐，长度不足的右边补空格
7) 对于格式未定的字段，可以通过类似%*.*f % (5,2,1.80)来设定表示%5.2f
8) 对于类型不确定的字段输出可以统一用%r表示，%r的格式化指定格式后面再学习。

2. format输出

1) 接受位置参数输出

>>> '{0}, {1}, {2}'.format('a', 'b', 'c')
'a, b, c'
>>> '{}, {}, {}'.format('a', 'b', 'c')  # 2.7+ only
'a, b, c'
>>> '{2}, {1}, {0}'.format('a', 'b', 'c')
'c, b, a'
>>> '{2}, {1}, {0}'.format(*'abc')      # unpacking argument sequence
'c, b, a'
>>> '{0}{1}{0}'.format('abra', 'cad')   # arguments' indices can be repeated
'abracadabra'

2) 接受参数名称输出

>>> print "His name is {name} and age is {age} ".format(age=18,name='Tom')
His name is Tom and age is 18 

3) 接受对象属性输出

>>> class person():
...     def __init__(self):
...         self.name='Jack'
...     def get_name(self):
...         print 'his name is {self.name}'.format(self=self)
>>> p.get_name()
his name is Jack

4) 接受序列的数据输出

>>> a=('tom','Jack','meng')
>>> print '{0[0]},{0[1]},{0[2]}'.format(a)
tom,Jack,meng

5) 格式化输出,可代替%s,%r

>>> print 'His name is {}'.format('tom')
His name is tom
>>> print 'His name is {:10}'.format('tom')
His name is tom       
>>> print 'His name is {:<10}'.format('tom')
His name is tom       
>>> print 'His name is {:>10}'.format('tom')
His name is        tom
>>> print 'His name is {:^10}'.format('tom')
His name is    tom    
>>> print 'His name is {:*<10}'.format('tom')
His name is tom*******
>>> print 'His name is {:.>10}'.format('tom')
His name is .......tom
>>> print 'His name is {:#^10}'.format('tom')
His name is ###tom####
>>> print 'His name is {:#10}'.format('tom')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: Alternate form (#) not allowed in string format specifier
>>> print '%08.2f'%(1.15)
00001.15
>>> print '%8.2f'%(1.15)
    1.15
>>> print '{:8.2f}'.format(1.15)
    1.15

说明: 指定填充字符适合必须要指明对齐方向

3. input / raw_input输入

>>> raw_var = raw_input("please input your content:")
please input your content:Testing python
>>> print raw_var
Testing python
>>> type(raw_var)
<type 'str'>
>>> 
>>> var = input("please input your content:")
please input your content:'Testing python'
>>> print var
Testing python
>>> type(var)
<type 'str'>
>>> var = input("please input your content:")
please input your content:Testing python
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "<string>", line 1
	Testing python
				^
SyntaxError: unexpected EOF while parsing
>>> 

>>> raw_var = raw_input("please input your content:")
please input your content:100+300
>>> print raw_var
100+300
>>> 
>>> var = input("please input your content:")
please input your content:100+300
>>> print var
4
>>> age = input('please input your age:')
please input your age:18
>>> print age
18
>>> type(age)
<type 'int'>

　　

总结：
1) raw_input将所有输入作为字符串看待，返回也是字符串类型
2) input 没有将所有输入作为字符串看待，所以在输入字符串内容时候需要添加引号，否则会出错
3) input可以接收表达式，并返回表达式结果
4）input返回也不一定是字符串类型；如果接收的是带引号的字符串那么返回的才是字符串类型；