Python数字加千分符

1、最简单的内置format函数：

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1 2	>>> format(1234567890,',') '1,234,567,890'

2、正则表达式：

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import re def formatNum(num):     num=str(num)     pattern=r'(\d+)(\d{3})((,\d{3})*)'     while True:         num,count=re.subn(pattern,r'\1,\2\3',num)         if count==0:             break     return num if __name__=='__main__':     print formatNum(1234455)

3、最笨的倒置后遍历过三位加逗号：

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def formatNum(num):     num=str(num)     result=''     count=0     for i in num[::-1]:         count+=1         result+=i         if count%3==0:             result+=','      return result[::-1].strip(',') if __name__=='__main__':     print formatNum(123445)