python 字符串格式化 ( 百分号 & format )

Python的字符串格式化有两种方式: 百分号方式、format方式

百分号的方式相对来说比较老，而format方式则是比较先进的方式，企图替换古老的方式，目前两者并存。

----百分号

 tpl = "i am %s" % "alex"
 #i am alex

 tpl = "i am %s age %d" % ("alex", 18)
 #i am alex age 18

 tpl = "i am %(name)s age %(age)d" % {"name": "alex", "age": 18}
 #i am alex age 18

 tpl = "percent %.2f" % 99.97623
 #percent 99.98

 tpl = "i am %(pp).2f %%" % {"pp": 123.425556, }
 #i am 123.43 %

----format

 tpl = "i am {}, age {}, {}".format("seven", 18, 'alex')
 #i am seven, age 18, alex
 tpl = "i am {}, age {}, {}".format(*["seven", 18, 'alex'])
 #i am seven, age 18, alex
 tpl = "i am {0}, age {1}, really {0}".format("seven", 18)
 #i am seven, age 18, really seven
 tpl = "i am {0}, age {1}, really {0}".format(*["seven", 18])
 #i am seven, age 18, really seven
 tpl = "i am {name}, age {age}, really {name}".format(name="seven", age=18)
 #i am seven, age 18, really seven
 tpl = "i am {name}, age {age}, really {name}".format(**{"name": "seven", "age": 18})
 #i am seven, age 18, really seven
 tpl = "i am {0[0]}, age {1[1]}, really {0[2]}".format([1, 2, 3], [11, 22, 33])
 #i am 1, age 22, really 3
 tpl = "i am {:s}, age {:d}, money {:f}".format("seven", 18, 88888.1)
 #i am seven, age 18, money 88888.100000
 tpl = "i am {:s}, age {:d}".format(*["seven", 18])
 #i am seven, age 18
 tpl = "i am {name:s}, age {age:d}".format(name="seven", age=18)
 #i am seven, age 18
 tpl = "i am {name:s}, age {age:d}".format(**{"name": "seven", "age": 18})
 #i am seven, age 18
 tpl = "numbers: {:b},{:o},{:d},{:x},{:X}, {:%}".format(15, 15, 15, 15, 15, 15.87623, 2)
 #numbers: 1111,17,15,f,F, 1587.623000%
 tpl = "numbers: {:b},{:o},{:d},{:x},{:X}, {:%}".format(15, 15, 15, 15, 15, 15.87623, 2)
 #numbers: 1111,17,15,f,F, 1587.623000%
 tpl = "numbers: {0:b},{0:o},{0:d},{0:x},{0:X}, {0:%}".format(15)
 #numbers: 1111,17,15,f,F, 1500.000000%
 tpl = "numbers: {num:b},{num:o},{num:d},{num:x},{num:X}, {num:%}".format(num=15)
 #numbers: 1111,17,15,f,F, 1500.000000%
 import math
 print('The value of PI is approximately {}.'.format(math.pi))
 #The value of PI is approximately 3.14159265359.
 print('The value of PI is approximately {!r}.'.format(math.pi))
 #The value of PI is approximately 3.141592653589793.
 print('The value of PI is approximately {0:.3f}.'.format(math.pi))
 #The value of PI is approximately 3.142.
 table = {'Sjoerd': 4127, 'Jack': 4098, 'Dcab': 7678}
 for name, phone in table.items():
     print('{0:10} ==> {1:10d}'.format(name, phone))
 '''
 Dcab       ==>       7678
 Jack       ==>       4098
 Sjoerd     ==>       4127
 '''
 table = {'Sjoerd': 4127, 'Jack': 4098, 'Dcab': 8637678}
 print('Jack: {0[Jack]:d}; Sjoerd: {0[Sjoerd]:d}; ''Dcab: {0[Dcab]:d}'.format(table))
 #Jack: 4098; Sjoerd: 4127; Dcab: 8637678