python笔记之字符串的使用

# 可以用' '|" "|""" """  来表示字符串
s1 = "你有100w软妹币"
print(s1)
# 需求：你有"100w"软妹币
# 利用引号嵌套方式
s2 = '你有"100w"软妹币'
print(s2)
# 利用转义字符
# \n => 换行符
s3 = "你有\"100w\"软妹币"
print(s3)

# 另外两种常见的字符串表示方式
# r"":原始字符串
# 字符串中所有合法字符都以原型显示
s4 = r"你有\"100w\"软妹币"
# b""：编码字符串
# 编码解码
# 知识扫盲：编码解码 utf-8 | gbk
# 进制：二进制 十进制 十六进制
s5 = "呵呵"
print(s5)
# 此时s5 为普通字符串
s5 = s5.encode("gbk") # 普通字符串可以进行编码
print(s5)
# 此时 s5 为编码字符串
# b'\xba\xc7\xba\xc7'

s5 = s5.decode("gbk") # 编码字符串可以进行解码
print(s5)
# 呵呵
# 1011 => 8421 => 8 + 2 + 1 >b
# ba =>10111010

s6 = b'\xba\xc7'
s6 = s6.decode('gbk')
print(s6)
# 呵


# + | * | [] |[:] | in |not in
# 字符串拼接
a = "hello"
b = 'world'
# hello world
res = a + " " + b  # 拼接得到的是新字符串，原字符串数据保留
print(res)
# hello world

name = "Bob"
tag = 1
name = name + str(tag)
print(name)
# Bob1

# 字符串重复
print("*" * 10)
# **********

# 取指定索引对应的字符 []
s7 = "今天天气不好！ ai..."
print(s7[0])
print(s7[8])
print(s7[-1])
print(s7[-5])
# 今
# a
# .
# a

# 切片;[:] 遵循半闭半开规则 [n,m) 从n取到m ,n <= res < m
print(s7[8:]) # 从索引8开始截取到最后
# ai...
print(s7[:-5]) # 从开始截取到倒数第五位之前
# 今天天气不好！
print(s7[4:6]) # 截取索引4,5号为字符
# 不好

# 字符存在与否判断
print("A" in s7) # False
print("a" not in s7) # False

# upper() | lower() |capitalize()| split() | join()
# 全大写
print("abc".upper())
# ABC
# 全小写
print("XZy".lower())
# xzy
# 首字母大写
print("hello".capitalize())
# Hello
# 拆分
#print("name='zero'@age='8'@gender='男'")
data = "name='zero'@age='8'@gender='男'"
res = data.split("@")
print(res)
# ["name='zero'", "age='8'", "gender='男'"]
# 拼接
# &=> name='zero'&age='8'&gender='男'
result = "&".join(res)
print(result)
# name='zero'&age='8'&gender='男'

# 需求：good good study day day up => Good Good Study Day Day Up
source = 'good good study day day up'
# step1:拆分
s_list = source.split(r' ')
print(s_list)
# step2:首字母大写
# 解压赋值
a,b,c,d,e,f = s_list
print(a,b,f) # good good up
# a = a.capitalize()
a = str(a).capitalize()
b = str(b).capitalize()
c = str(c).capitalize()
d = str(d).capitalize()
e = str(e).capitalize()
f = str(f).capitalize()
# step3: 合并
result = r" " .join([a, b, c, d, e, f])
print(result) # Good Good Study Day Day Up
python笔记之字符串的使用

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