Home Backend Development Python Tutorial Python中用startswith()函数判断字符串开头的教程

Python中用startswith()函数判断字符串开头的教程

Jun 06, 2016 am 11:24 AM
python

函数:startswith()

作用:判断字符串是否以指定字符或子字符串开头

一、函数说明
语法:string.startswith(str, beg=0,end=len(string))
       或string[beg:end].startswith(str)
 
参数说明:
string:  被检测的字符串
str:      指定的字符或者子字符串。(可以使用元组,会逐一匹配)
beg:    设置字符串检测的起始位置(可选)
end:    设置字符串检测的结束位置(可选)
如果存在参数 beg 和 end,则在指定范围内检查,否则在整个字符串中检查

返回值
如果检测到字符串,则返回True,否则返回False。默认空字符为True

函数解析:如果字符串string是以str开始,则返回True,否则返回False


二、实例

>>> s = 'hello good boy doiido'
>>> print s.startswith('h')
True
>>> print s.startswith('hel')
True
>>> print s.startswith('h',4)
False
>>> print s.startswith('go',6,8)
True

#匹配空字符集
>>> print s.startswith('')
True
#匹配元组
>>> print s.startswith(('t','b','h'))
True

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常用环境:用于if判断

>>> if s.startswith('hel'):
 print "you are right"
else:
 print "you are wrang"

you are right

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