a = 'Hello world'
# upper全部大写
print(a.upper()) ==》HELLO WORLD
# lower全部小写
print(a.lower()) ==》hello world
# title首字母大写
print(a.title()) ==》Hello World
# capitalize首字母变大写
print(a.capitalize()) ==》Hello world
# swapcase大写变小写。小写变大写
print(a.swapcase())
# count统计字符出现的次数
print(a.count('o')) ==》2
# replace替换字符
b= a.replace('world','python')
print(b) ==》Hello python
# find 查找指定字符 ==》找到该字符串的索引位置。如果找不到就返回-1
index1= a.find('wo')
index2= a.find('ow')
print(index1) ==》6
print(index2) ==》-1
# index 方法如果找不到就会报错 ValueError值错误
result1= a.index('wo')
result2= a.index('ow')
print(result1,result2) ==》ValueError
# join 组合，连接字符串数组。将字符串、元组、列表中的元素以指定的字符(分隔符)连接生成一个新的字符串
person_info= ['Tom','男','27','180']
person_info= ','.join(person_info)
print(person_info) ==》Tom,男,27,180
# split 拆分，按某一个字符分割，且分割n次
person_info1= ('hello,world')
person_info1= person_info1.split(',')
print(person_info1) ==》 ['hello', 'world']
# strip 去掉头和尾指定的字符,中间无法去除
d= '666Helleo 6 python!666'
f= d.strip('6')
print(f) ==》Helleo 6 python!
