字符串也不可修改,任何修改的字符串全是新的字符串
msg = “ abc “
msg2 = “abc\n” # \n换行符
msg3 = “asd asdad”
msg4 = “a.jpg”
new_msg = msg.strip() # 默认去掉字符串俩边的空格和换行,中间是去不掉的
print(msg)
print(new_msg)
print(msg2)
print(msg2.strip())
print(msg3)
print(msg4.strip(“.jpg”)) # 如果你指定了一个字符串,就会去掉指定的字符串
print(msg3.lstrip()) # 只去左边的
print(msg3.rsplit()) # 只去右边的

words = “sadjaskds2342323df3423498kjsasa”
print(words.find(“s”)) # 如果查询不到这个字符串,就返回-1,查询到的话就返回它的下标
print(words.index(“d”)) # 如果查询不到这个字符串,就报错,查询到的话就返回它的下标

print(words.replace(“sa”,”SA”,1)) #搜前边替后边的,最后可以加替换几个,不加全替换
print(words.replace(“ “,””)) #可用用作去除空格

print(words.upper()) #都替换成大写
print(words.lower()) #都替换成小写

msg3 = “touxiang.jpg”
print(msg3.isdigit()) #判断字符串是否都是整数
print(msg3.isupper()) #判断字符串是否都是大写字母
print(msg3.islower()) #判断字符串是否都是小写字母
print(msg3.endswith(“.jpg”)) #判断某个字符串结尾
print(msg3.startswith(“.jpg”)) #判断某个字符串开头

msg3=”sdg”
print(msg3.isspace()) #判断是否为空
print(msg3.title())
print(msg3.istitle())
print(msg3.capitalize()) #首字母大写
print(msg3.center(30,”*”)) #本身字符串居中,然后补齐

print(msg3.isalnum()) #字符串如果是字母或数字或中文,就返回true
print(msg3.isalpha()) #字符串如果是字母或中文他就返回true

number = input(“number:”)
print(number.zfill(3)) #补0,如果长度不够的话,就在前边补0

msg4 = “admin,dev,test1,abc”
result = msg4.split(“,”) #分割字符串
print(result)

stus = [“admin”,”dev”,”test1”,”abc”]
str_stu = str(stus)
print(“”.join(stus)) #如果使用join方法,必须得保证list里面的每个元素都是字符串才可以,“”中的符号为各元素以什么链接起来
print(“ “.join(stus))
print(“,”.join(stus))
ret = “=”.join(stus)
print(ret)

username = “王瑞”
msg = “欢迎” + username + “登录”
print(msg)

#会报错,因为1不是字符串类型
# username = 1
# msg = “欢迎” + username + “登录”
# print(msg)

username = input(“请输入你的名字: “)
today = str(datetime.datetime.today())
msg1 = “欢迎” + username + “登录” + “,今天的日期是” + today
print(msg1)
msg2 = “欢迎%s登录” % username
msg3 = “欢迎%s登录,今天的日期是%s” % (username,today)
msg4 = “你的年龄是%d,你的分数是%.2f” % (19,23.5555) # %d必须是整数,%f代表小数,%.2f代表2位小数
msg5 = “你的年龄是%s,你的分数是%s” % (19,23.5555) #实际工作中统一用%s可以

python 3.6以上才可用
# msg6 = f”你的名字是{username},今天的日期是{today}”
msg7 = “你的名字是{},今天的日期是{}”.format(username,today)
msg8 = “你的名字是{name},今天的日期是{today},你的年龄是{age}”.format(age = 18,today = today,name = username) #这种可以不按顺序写,自动匹配变量名

print(msg7)
print(msg8)

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