replace   替换

语法：str.replace(oldvalue, newvalue[, count])

oldvalue：将被替换的子字符串

newvalue：用于替换oldvalue的子字符串

count：数值次数，指定要替换多少个oldvalue，如果次数没有输入的话，那么久默认全部替换成新的字符串

a="hello world "                                     a="hello world world world world"           a="hello world world world world" 

print(a.replace("world","wo"))              print(a.replace("world","wo"))                  print(a.replace("world","wo,2"))

hello wo                                                  hello  wo   wo  wo  wo                                hello  wo   wo   world world

https://blog.csdn.net/Hudas/article/details/128205412?ops_request_misc=%257B%2522request%255Fid%2522%253A%2522169573976716800188544297%2522%252C%2522scm%2522%253A%252220140713.130102334..%2522%257D&request_id=169573976716800188544297&biz_id=0&utm_medium=distribute.pc_search_result.none-task-blog-2~all~top_positive~default-1-128205412-null-null.142^v94^insert_down1&utm_term=replace%E5%87%BD%E6%95%B0&spm=1018.2226.3001.4187

join     连接
语法：'sep'.join(sep_object)

sep：分割符，可为“，、；”,分隔符里面为空的话，那么就是元素或者字符串所有的值都合在一起了。

sep_object：分割对象，可为字符串、以及储存字符串的元组、列表、字典。

a=("hello","world","world","world","world")

print(".".join(a))

hello.world.world.world.world

a=["hello","world","world","world","world"]

print(".".join(a))

hello.world.world.world.world

a=("hello","world","world","world","world")

print(" ".join(a))

helloworldworldworldworld

81.字符串的常用操作_替换与合并_哔哩哔哩_bilibili  9.26

https://blog.csdn.net/weixin_50853979/article/details/125119368?ops_request_misc=&request_id=&biz_id=102&utm_term=python%20join%E5%87%BD%E6%95%B0&utm_medium=distribute.pc_search_result.none-task-blog-2~all~sobaiduweb~default-1-125119368.142^v94^insert_down1&spm=1018.2226.3001.4187