Python -- 字符串大小写转换

①所有字母都转换为大写

# -*- coding:utf-8 -*-

if __name__ == "__main__":
    a = 'hello, world!'
    print(a.upper())

输出：

HELLO, WORLD!

②所有字母都转换为小写

# -*- coding:utf-8 -*-

if __name__ == "__main__":
    a = 'HELLO, WORLD!'
    print(a.lower())

输出：

hello, world!

③首字母转换成大写， 其余转换成小写

# -*- coding:utf-8 -*-

if __name__ == "__main__":
    a = 'HELLO, WORLD!'
    print(a.capitalize())

输出：

Hello, world!

④所有单词的首字母转换成大写， 其余转换成小写

# -*- coding:utf-8 -*-

if __name__ == "__main__":
    a = 'HELLO, WORLD!'
    print(a.title())

输出：

Hello, World!

⑤判断所有字母都为大写

# -*- coding:utf-8 -*-

if __name__ == "__main__":
    a = 'HELLO, WORLD!'
    print(a.isupper())
    
    b = 'hello, world!'
    print(b.isupper())

输出：

True
False

⑥判断所有字母都为小写

# -*- coding:utf-8 -*-

if __name__ == "__main__":
    a = 'HELLO, WORLD!'
    print(a.islower())
    
    b = 'hello, world!'
    print(b.islower())

输出：

False
True

⑦判断所有单词的首字母为大写

# -*- coding:utf-8 -*-

if __name__ == "__main__":
    a = 'HELLO, WORLD!'
    print(a.istitle())
    
    b = 'hello, world!'
    print(b.istitle())
    
    c = 'Hello, World!'
    print(c.istitle())

输出：

False
False
True