1.修改字符串首字母的大小写
代码演示:
s1 = 'hello'
print(s1)
print(s1.capitalize())
#s1[0] = 'H' 只读的,会抛出异常
s1 = s1[0:1] + s1[1].upper() + s1[2:]
print(s1)
s2 = 'Hello'
s = s2[0].lower() + s2[1:]
print(s)
运行结果:
2.如何将字符串中每一个单词的首字母变成大写
代码演示:
s3 = 'hello world'
print(s3.capitalize())
a = s3.split(' ')
new_str = f'{a[0].capitalize()} {a[1].capitalize()}'
print(new_str)
运行结果:
3.如何反转一个字符串
代码演示:
s1 = 'abcd'
s2 = ""
for i in s1: #麻烦
s2 = i + s2
print(s2)
运行结果:
4.如何用切片反转字符串
代码演示:
s1 = 'abcd'
print(s1[::1]) #简便
print(s1[::2])
print(s1[::-1])
运行结果:
用到的知识点:
1. capitalize 只有字符串的首字母大写
2. upper 将字符串当中所有的字母转换为大写
3. lower 将字符串当中所有的字母转换为小写