python开发_python中str.format()

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　　格式化一个字符串的输出结果，我们在很多地方都可以看到，如：c/c++中都有见过
　　下面看看python中的字符串格式函数str.format():



1 #使用str.format()函数
2
3 #使用'{}'占位符
4 print('I\'m {},{}'.format('Hongten','Welcome to my space!'))
5
6 print('#' * 40)
7
8 #也可以使用'{0}','{1}'形式的占位符
9 print('{0},I\'m {1},my E-mail is {2}'.format('Hello','Hongten','hongtenzone@foxmail.com'))
10 #可以改变占位符的位置
11 print('{1},I\'m {0},my E-mail is {2}'.format('Hongten','Hello','hongtenzone@foxmail.com'))
12
13 print('#' * 40)
14
15 #使用'{name}'形式的占位符
16 print('Hi,{name},{message}'.format(name = 'Tom',message = 'How old are you?'))
17
18 print('#' * 40)
19
20 #混合使用'{0}','{name}'形式
21 print('{0},I\'m {1},{message}'.format('Hello','Hongten',message = 'This is a test message!'))
22
23 print('#' * 40)
24
25 #下面进行格式控制
26 import math
27 print('The value of PI is approximately {}.'.format(math.pi))
28 print('The value of PI is approximately {!r}.'.format(math.pi))
29 print('The value of PI is approximately {0:.3f}.'.format(math.pi))
30
31
32 table = {'Sjoerd': 4127, 'Jack': 4098, 'Dcab': 7678}
33 for name, phone in table.items():
34     print('{0:10} ==> {1:10d}'.format(name, phone))
35
36
37 table = {'Sjoerd': 4127, 'Jack': 4098, 'Dcab': 8637678}
38 print('Jack: {0[Jack]:d}; Sjoerd: {0[Sjoerd]:d}; ''Dcab: {0[Dcab]:d}'.format(table))
　　运行效果：



Python 3.3.2 (v3.3.2:d047928ae3f6, May 16 2013, 00:03:43) [MSC v.1600 32 bit (Intel)] on win32
Type "copyright", "credits" or "license()" for more information.
>>> ================================ RESTART ================================
>>>
I'm Hongten,Welcome to my space!
########################################
Hello,I'm Hongten,my E-mail is hongtenzone@foxmail.com
Hello,I'm Hongten,my E-mail is hongtenzone@foxmail.com
########################################
Hi,Tom,How old are you?
########################################
Hello,I'm Hongten,This is a test message!
########################################
The value of PI is approximately 3.141592653589793.
The value of PI is approximately 3.141592653589793.
The value of PI is approximately 3.142.
Jack       ==>       4098
Sjoerd     ==>       4127
Dcab       ==>       7678
Jack: 4098; Sjoerd: 4127; Dcab: 8637678
>>>