Python Day 1 基础 数据类型
10. 数据类型
1)数字
* 整型int
* 长整型long
* 浮点型float
* 复数complex
2)布尔值
真或假
1或0
3)字符串
特性:不可修改
“Hello world“
字符串格式化输出
name="alex”
print("i am %s" %name)
PS:
字符串%s
整数%d
浮点数%f
字符串的常用功能:
- 移除空白
name=" hello world "
print(name.lstrip())
print(name.rstrip())
print(name.strip())
print(name.replace(" ","")) *
- 分割
a="1,23,45,67,8"
print(a.split(","))
- 长度
name=" hello world "
print(len(name))
- 索引(查找字符串)
a="12345678"
b="45678"
c=a.index(b)
print(c)
- 切片
a="12345678"
print(a.split("5"))
- 连接字符串
a="1"
b="2"
a +=b
print(a)
- 截取字符串
print (str[0:3]) #截取第一位到第三位的字符
print (str[:]) #截取字符串的全部字符
print (str[6:]) #截取第七个字符到结尾
print (str[:-3]) #截取从头开始到倒数第三个字符之前
print (str[2]) #截取第三个字符
print (str[-1]) #截取倒数第一个字符
print (str[::-1]) #创造一个与原字符串顺序相反的字符串
print (str[-3:-1])#截取倒数第三位与倒数第一位之前的字符
print (str[-3:]) #截取倒数第三位到结尾
print (str[:-5:-3]) #逆序截取,具体啥意思没搞明白?
- 其他
name="eric"
print(name.capitalize())
print(name.casefold())
print(name.center(50,"1"))
print(name.center(50,"1").count("1"))
print(name.encode())
print(name.find("i"))
4)列表
创建列表:
name_list=['alex','seven','eric']
print(name_list[0])
基本操作:
- 索引(获取下标)
name_list=['alex','seven','eric']
print(name_list.index("seven"))
- 切片
name_list=['alex','seven','eric']
print(name_list[1:])
- 追加
name_list=['alex','seven','eric']
name_list.append("mark")
name_list.append("mark2")
print(name_list)
- 删除
name_list=['alex','seven','eric']
del name_list[0]
name_list.remove("seven")
print(name_list)
- 插入
name_list=['alex','seven','eric']
name_list.insert(1,"alex1")
print(name_list)
- 修改
name_list=['alex','seven','eric']
name_list[2]="eric2"
print(name_list)
- 长度
name_list=['alex','seven','eric']
print(len(name_list))
- 循环
a=[1,2,3,4,5,6]
for x in a:
print(x)
- 包含
a=[[1],2,3,4,5,6]
b=[1,3]
c=[1]
print(b in a)
print(c in a)
- 扩展
name_list=['alex','seven','eric']
b=[1,3,2]
name_list.extend(b)
print(name_list)
- 拷贝
name_list=['alex','seven','eric']
name_copy=name_list.copy()
print(name_copy)
- 统计
name_list=['alex','seven','eric']
print(name_list.count("seven"))
- 排序&翻转
name_list=['alex','seven','eric']
name_list.sort()
print(name_list)
name_list.reverse()
print(name_list)
5)元组(不可变列表)
创建元组:
age=(11,12,13,14,15)
print(age[0])
常用功能
- count
- index
6)字典(无序)
创建字典:
person={"name":"mr.wu","age":18}
print(person["name"])
基本操作:
- 索引
person={"name":"mr.wu","age":18}
print(person["name"])
print(person["age"])
- 新增
person={"name":"mr.wu","age":18}
person.update({"name":"mr.wang","age":20})
print(person)
or
person["name"]="mr.zhang"
print(person)
- 删除
person={'stu1102': '1', 'stu1103': '2', 'stu1101': '3'}
person.pop("stu1101")
print(person)
del person["stu1102")
print(person)
- 查找
person={'stu1102': '1', 'stu1103': '2', 'stu1101': '3'}
if "stu1103" in person:
print("ok")
print(person.get("stu1100"))#出现none
print(person["stu1100"]) #报错
-
字典嵌套
详见作业二 -
循环
person={'stu1102': '112', 'stu1103': '223', 'stu1101': '334'}
for i,v in person.items():#转换成list
print(i,v)
for i in person:
print(i,person[i])
- 转换成list
print(person.items())
7)集合
集合是一个无序的,不能重复的组合,
* 自动去重
* 关系测试,交集、差集、并集