s = "abeccc   c   "s2 = s.strip('c')  # 默认去掉字符串两边的空格和换行符print(s2)print(s)print(s.count('c'))  # 返回这个值有几个index1 = s.index('c')  # 返回第一次出现的位置

print(index1)

print(s.capitalize())  # 首字母大写print(s.upper())  # 全部变成大写print(s.lower())  # 全部变成小写print(s.replace("c", "Fuck", 2))  # 替换字符串，若不存在不报错,也可以后面加上要替换的数字比如1print(s.replace(" ", ""))  # 替换字符串，若不存在不报错print('abc.jpg'.endswith(".jpg"))  # 判断是否以定义的字符串结尾print('abc.jpg'.startswith("c"))  # 判断是否以定义的字符串开头print("欢迎登录：".center(20, "*"))  # 把字符串放在中间，一共20个字符以*前后填充

print(s.isspace())  # 判断是否是空格字符串print(s.isalnum())  # 没有特殊字符返回trueprint(s.islower())print(s.isupper())print(s.isalpha())  # 不是数字，不是特殊符号，返回trueprint(s.isdigit())  # 整数返回trueprint(s.zfill(20))  # 字符串长度不够，前面补0s2 = "欢迎{}登录，今天的日期是{}"uname = "dongxl"today = '2019-3-30'print(s2.format(uname, today))s3 = 'insert into user value ({username},{password},{addr}) '  # 给｛｝的参数赋值，不用考虑顺序new_s3 = s3.format(username="dongxl", addr="上海", password="123")  # 给｛｝的参数赋值，不用考虑顺序new_s4 = s3.format_map({"password": 123, "addr": "上海", "username": "dongxiuli"})  # 可以赋值key  valueprint(new_s3)print(new_s4)

# ===============================字符串2

users = "abc,xiaohei,xiaobai,xiaoming"result = users.split(",")# 1按照某个字符串分割，# 2然后把分割后的元素放到一个list里面，# 3如果指定的字符串不存在，，那么就把整个字符串放到list里面print(result)

# 产生一批用户名li = ['abc,xiaohei,xiaobai,xiaoming']print(','.join(li))  # abc,xiaohei,xiaobai,xiaoming  把list转换为字符串# 把list变成字符串# 2、用指定的字符串把list里面的每个元素连接起来

f = open("names.txt", 'w', encoding='utf-8')f.write(','.join(li))# f.write(str(li)) 带引号以及[]都放在了文件f.close()f = open("names.txt", 'r', encoding='utf-8')res = f.read()print("从文件里面读出来的数据：", res)f.close()f2= open("regist.txt", 'r+', encoding='utf-8')res2 = f2.read()print("从文件里面读出来的数据2：", res2)