浅析python3字符串格式化format()函数的简单用法

"""
测试 format()函数
"""
def testFormat():
  # format()函数中有几个元素，前面格式化的字符串中就要有几个 '{}'
  # 位置
  s1 = 'a{}b{}c{}d{}'.format(1, 2, 3, 4)
  # 索引，format()函数中的元素，从0开始
  s2 = 'a{0}b{1}c{3}d{2}'.format(1, 2, 3, 4)
  # 索引可以重复使用
  s3 = 'a{0}b{1}c{0}d{1}'.format(1, 2, 3, 4)
  print('-' * 8)
  print('一般用法：')
  print(s1)
  print(s2)
  print(s3)
  print('-' * 8)
  # format()函数中元素个数，和前面的字符串中的'{}'个数不相同
  # 格式化字符串中的'{}'里面必须要有后面format()函数中元素的索引
  s4 = 'a{0}b{1}cd'.format(1, 2, 3, 4)
  s5 = 'a{0}b{1}c{0}d{1}e{1}f{1}g{1}h{1}{4}{4}{4}{4}{5}{4}{4}{4}{4}'.format(1, 2, 3, 4, '*', '哈哈，这是第6个数，索引是5')
  print('其他用法：')
  print(s4)
  print(s5)
  print('-' * 8)
  return
if __name__ == '__main__':
  testFormat()

 >>> li = ['hoho',]
 >>> 'my name is {} ,age {}'.format('hoho',)
 'my name is hoho ,age '
 >>> 'my name is {} ,age {}'.format(,'hoho')
 'my name is hoho ,age '
 >>> 'my name is {} ,age {} {}'.format(,'hoho')
 'my name is hoho ,age hoho'
 >>> 'my name is {} ,age {}'.format(*li)
 'my name is hoho ,age '

 >>> hash = {'name':'hoho','age':}
 >>> 'my name is {name},age is {age}'.format(name='hoho',age=)
 'my name is hoho,age is '
 >>> 'my name is {name},age is {age}'.format(**hash)
 'my name is hoho,age is 18'

 >>> '{:*>}'.format() ##右对齐
 '********'
 >>> '{:*<}'.format() ##左对齐
 '********'
 >>> '{:*^}'.format() ##居中对齐
6 '****10****'

 >>> '{:.f}'.format(/)
 '.'
 >>> '{:b}'.format()  #二进制
 ''
 >>> '{:o}'.format()   #八进制
 ''
 >>> '{:x}'.format()   #进制
 'a'
 >>> '{:,}'.format() #千分位格式化
 ',,,'

 >>> li
 ['hoho', ]
 >>> 'name is {[]} age is {[]}'.format(li)
 'name is hoho age is