零基础学python-7.4 修改字符串实例总结
我们知道python里面字符串是不可原处直接修改的,为了是原来的字符串修改过来,我们有一下方法:
1.分片和合并
>>> a="abcde"
>>> b="fghij"
>>> c=a[1:3]+b[2:5]+" end"
>>> c
"bchij end"
>>>
2.replace()
>>> a="aaabbbcccddd"
>>> a.replace ("aaa","xxx")
"xxxbbbcccddd"
>>>
3.结合find()和分片
>>> a="aaaxbbbcccxddd"
>>> where = a.find ("x")
>>> where
3
>>> a[:where]+"ttttt"+a[where:]
"aaatttttxbbbcccxddd"
>>>
上面的三种方法,虽然都修改了源字符串,其实它们没有直接在原处修改,只是重新创建一个新的字符串对象
4.使用可修改的列表
可能你需要修改超长文本多个地方,这时候上面的方法性能不好,所以需要转换为可以修改的对象-列表
>>> a="aaaxbbbcccxddd"
>>> b=list(a)
>>> b
["a", "a", "a", "x", "b", "b", "b", "c", "c", "c", "x", "d", "d", "d"]
>>> b[2]="x"
>>> b[7]="x"
>>> b
["a", "a", "x", "x", "b", "b", "b", "x", "c", "c", "x", "d", "d", "d"]
>>> a="".join (b)
>>> a
"aaxxbbbxccxddd"
>>>
就说到这里,谢谢大家