"Python".lower() 'python'
"Python".upper() 'PYTHON'
"Sunshine always comes after the rain".split()#默认以空格分割
['Sunshine', 'always', 'comes', 'after', 'the', 'rain']
"姓名，年龄，性别，电话，住址".split(",")
['姓名，年龄，性别，电话，住址']#(因为两个逗号不是同一种
"Everything will be ok".count("i") # 统计“i”出现的次数
"Sunshine always comes after the rain".replace(" ",",")
# 把原来的“ ”替换为“，”
"Python".center(15,"*") # 字符串居中，用“*”填补空余
'*****Python****'
"Python".center(3,"*")
'Python'
"###brave###".strip("#") # 去掉字符串中左右出现的“#”字符
'brave'
>>> ls = ["Python","Java","C++","Jsp"]
>>> "**".join(ls) # 每一个元素后面都加一个“**”
'Python**Java**C++**Jsp'
>>> ",".join("12345")
'1,2,3,4,5'
