python在对找到的匹配项进行适当处理后，再替换掉原来那个匹配的项。

#!/usr/bin/python
# coding=GBKimport re# 对m作适当处理后返回结果
def fun(m):print("in: %s" %m.group(0))ret = m.group(0).upper()[::-1]return retsrc = "what [can] I do for can you[can] come on"
pat = "(?<=\[)(can)(?=\])"
#print(re.search(pat, src).group(1))
#result = re.sub(pat,lambda m:m.group(1).upper()[::-1], src)# 使用lambda
result1 = re.sub(pat, lambda m:m.group(0).upper()[::-1], src)
print("result1: %s\n" %result1)# 在re.sub中使用函数
result2 = re.sub(pat, fun, src)
print("result2: %s" %result2)

运行输出：

[zcm@python #112]$./del.py 
result1: what [NAC] I do for can you[NAC] come onin: can
in: can
result2: what [NAC] I do for can you[NAC] come on
[zcm@python #113]$

看到了吗， 所有匹配"[can]"的项都被“转换成大写并逆顺”了。