5 - 改变字符串首字母的大小写

s1 = 'hello'
print(s1)
print(s1.capitalize())

# s1[0] = 'H'  # 只读的，会抛出异常

# 分片
s1 = s1[0:1] + s1[1].upper() + s1[2:]
print(s1)

s2 = 'Hello'
s = s2[0].lower() + s2[1:]
print(s)

hello

Hello

hEllo

hello

s3 = 'hello world'
print(s3.capitalize())

# 拆分字符串
arr = s3.split(' ')
# 连接字符串
new_str = f'{arr[0].capitalize()} {arr[1].capitalize()}'
print(new_str)

Hello world

Hello World