1.字符串运算 1.1 拼接字符串 if __name__ == "__main__" :"张三" "男" print ("使用 + 拼接 >> " , "姓名:" + name + " 性别:" + sex)print ("使用 print 格式化 >> 姓名:%s 性别:%s " % (name, sex))"姓名:{} 性别:{} " .format (name, sex)print ("使用 format >> " , format_var)
1.2 重复字符串 if __name__ == "__main__" :"张三" print ("使用:* >>" , name * 3 )
1.3 截取字符串 if __name__ == "__main__" :"我的名字叫张三丰~" print ("截取前3个字符串 >>" , str_var[:3 ])print ("从索引=5,开始截取 >>" , str_var[5 :])print ("从索引=1,开始截取，到索引=5为止 >>" , str_var[1 :5 ])print ("演示:[i:j:k]" , str_var[1 :8 :2 ])
1.4 原样输出 if __name__ == "__main__" :"我的名\n 叫张三丰 \n 哈哈哈" print ("str_var >>" , str_var)r"我的名\n 叫张三丰 \n 哈哈哈" print ("r_str_var >>" , r_str_var)
2. 大小写 2.1 首字母大写 if __name__ == "__main__" :"my name is liu qing hui" print ("所有字符串首字母大写 title:" , str_var.title())print ("第一个字符串首字母大写 capitalize:" , str_var.capitalize())
2.2 全部大写 if __name__ == "__main__" :"my name is liu qing hui" print ("全部转大写:" , str_var.upper())
2.3 全部小写 if __name__ == "__main__" :"MY NAME IS LIU QING HUI" print ("全部小写 lower:" , str_var.lower())print ("全部小写 casefold :" , str_var.casefold())
lower()方法只对ASCII字符有效，而casefold()方法对所有Unicode字符都有效.
2.4 大转小和小转大 if __name__ == "__main__" :"Hello,World" print ("原字符串:" , str_var)print ("大转小,小转大:" , str_var.swapcase())
3. 统计 3.1 字符串出现次数 if __name__ == "__main__" :"abcd,abcd,abcd" print ("字符串a出现的次数:" , str_var.count("a" ))print ("str_var[0:7]:" , str_var[0 :7 ])print ("字符串a在str_var[0:7]出现的次数:" , str_var.count("a" , 0 , 7 ))
3.2 字符串长度 if __name__ == "__main__" :"Hi,张三丰" "Hi" "张三丰" print ("str_var长度:" , len (str_var))print ("str_var2长度:" , len (str_var2))print ("str_va3r长度:" , len (str_var3))
4. 查找 4.1 字符串是否存在
find()： 不存在则返回-1,存在则从返回第一个匹配的索引。
if __name__ == "__main__" :"Hello,World" print ("h是否在字符串中:" , str_var.find("h" ))print ("o是否在字符串中:" , str_var.find("o" ))
index()和find()方法一样，区别是:当子字符串不存在时，index()会报异常，推荐使用find()
4.2 使用 if __name__ == "__main__" :"Hello,张三" print ("H in str_var >>" , "H" in str_var)print ("H not in str_var >>" , "H" not in str_var)print ("张三 in str_var >>" , "张三" in str_var)
5. 判断 5.1 是否只包含字符或数字 if __name__ == "__main__" :"hello" print ("str1:" , str1.isalnum())"hello123" print ("str2:" , str2.isalnum())"hello@123" print ("str3:" , str3.isalnum())"hello张三" print ("str4:" , str4.isalnum())
5.2 是否只包含字符 if __name__ == "__main__" :"hello" print ("str1:" , str1.isalpha())"hello123" print ("str2:" , str2.isalpha())"hello@123" print ("str3:" , str3.isalpha())"hello张三" print ("str4:" , str4.isalpha())
5.3 是否只包含数字字符(0-9) if __name__ == "__main__" :"123456@" print ("str1:" , str1.isdigit())"123456" print ("str2:" , str2.isdigit())"张三18" print ("str3:" , str3.isdigit())
5.4 是否只包含数字字符 if __name__ == "__main__" :"123456" print ("str2:" , str1.isnumeric())"一2三4五" print ("str2:" , str2.isnumeric())
5.5 是否有空白符
空白字符包括空格、制表符、换行符和回车符等
if __name__ == "__main__" :" " print ("str1:" , str1.isspace())"\t\n" print ("str2:" , str2.isspace())"hello world " print ("str3:" , str3.isspace())
5.6 是否首字母大写 if __name__ == "__main__" :"Hello world" print ("str1:" , str1.istitle())"Hello World" print ("str2:" , str2.istitle())
6.删除和替换 6.1 替换 if __name__ == "__main__" :"a-b-a-b-a-b-a-b" print ("全部替换结果：" , str1.replace("a" , "@" ))print ("从左往右替换结果1次：" , str1.replace("a" , "@" , 1 ))print ("从左往右替换结果2次：" , str1.replace("a" , "@" , 2 ))print ("从左往右替换结果4次：" , str1.replace("a" , "@" , 4 ))
6.2 删除 if __name__ == "__main__" :" 1 # abc@ " print ("删除左右空白：" , str1.strip())print ("删除右边空白：" , str1.rstrip())print ("删除左边空白：" , str1.lstrip())
7.分割和拼接 7.1 分割 if __name__ == "__main__" :str = "Hello,World" print ("res: " , str .split("," ))
7.2 拼接 if __name__ == "__main__" :"a" , "b" , "c" , "d" ]print ("res: " , "|" .join(list_var))"abcd" print ("res2: " , "-" .join(str1))
8.格式化 if __name__ == "__main__" :"姓名:{} 年龄:{}" print (format1.format ("张三" , 18 ))"姓名:{1} 年龄:{0}" print (format2.format ("张三" , 18 ))"姓名:{0}{0} 年龄:{1}" print (format3.format ("张三" , 18 ))"姓名:{name} 年龄:{age}" print (format4.format (age=18 , name="张三" ))
