re.match心得

error multiple repeat at position

现象

代码

hrefP = "(https?://)?%s/?" % aStr
isSameUrl = re.match(hrefP, hrefValue, re.I)

要去匹配的值aStr

'Is there a way to get a call graph for certain c++ function in Visual Studio? - Stack Overflow'

报错：

发生异常: error
multiple repeat at position 61

原因

字符串中包含特殊的正则字符+，且是连续的++

导致逻辑上不成立：++在规则中是不合法的

解决办法

确保正则的pattern中，没有无效的规则。

此处即，把特殊字符，都替换，加上反斜杠\去转义：

具体步骤

改为：

SpecialCharList = [
    ".",
    "+",
    "*",
    "?",
]
for eachSpecialChar in SpecialCharList:
    escapedChar = "\%s" % eachSpecialChar # '\\.'
    aStr = aStr.replace(eachSpecialChar, escapedChar)
# 'Is there a way to get a call graph for certain c++ function in Visual Studio? - Stack Overflow'
# ->
# 'Is there a way to get a call graph for certain c\\+\\+ function in Visual Studio\\? - Stack Overflow'

hrefP = "(https?://)?%s/?" % aStr
isSameUrl = re.match(hrefP, hrefValue, re.I)